Cec 103.- Workshop Technology 1

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TABLE OF CONTENT

Title page

Content

WEEK ONE

1. Sketch of site layout showing how to set out a simple residential building foundation

and superstructure

1.1 Site plan

1.2 Example:practical to set out site

FIG: 1.1: Site plan showing boundaries and adjacent roads

FIG: 1.2: Site plan with landscaping

WEEK TWO

2. Execution of foundation trench and casting concrete

2.1 Trench excavation

2.2 Timbering of trench excavation

2.3 Trench preparation for concrete foundation

FIG: 2.1: Timbering in trench excavation

WEEK THREE

3. Mixing of concrete

3.1 Batching

3.2 Mixing

3.3Handling


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3.4 Placing

3.5 Specifying concrete

3.6 Example:

FIG: 3.1. concrete mixer

FIG: 3.2. placing of concrete

FIG: 3.3. a model mobile concrete mixer

FIG: 3.4. a wheelbarrow

WEEK FOUR

4. Setting out of a simple resdential building block wall super structure

FIG: 4.1. Setting out of block wall superstructure

WEEK FIVE

5. Plumbing of pipes for waste water as drainage

5.1 System of drainage

5.2 Choice of pipes

5.3 Setting out of drainage system

5.4 Laying of pipes

5.5 Jointing of pipes

5.6 Drainage test

FIG: 5.1. Couplings and vents

FIG: 5.2. Drainage system


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WEEK SIX

6. Laying of blocks/bricks in different bonds

6.1 Purpose of bonding

6.2 Choice of brick bond

6.3 Choice of mortar.

6.4 Principles of bonding of brickwork

6.5Types of bond

6.6 Setting out bonds

FIG: 6.1. Stretcher bond

FIG: 6.2. English bond

FIG: 6.3. Flemish bond

FIG: 6.4. Header bond

FIG: 6.5. Brick bonds

FIG: 6.5. A brick wall

WEEK SEVEN

7. Identification of construction wood types and their sizes

7.1 Construction wood types:

7.2 common sizes of timber

FIG: 7.1. Internal structure of wood

FIG: 7.2. Sawn wood

WEEK EIGHT

8. Preparation of piece of wood by hand and machine

8.1 Hand preparation of member


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8.2 Machine preparation

WEEK NINE

9. LAYOUT OF A STANDARD CARPENTRY AND JOINERY WORKSHOP

9.1 standard carpentry and joinery workshop

9.2 example: 1

FIG: 9.1: Standard carpentry and joinery workshop




WEEK TEN

10. Preparation for joints in wood work

10.1 Types of joints

10.2 Example: 1

FIG: 10.1.Halved joint

FIG: 10.2.Halved joints

FIG: 10.3. Bridle joint

FIG:10.4. Mortice and tenon joint

FIG: 14.5. Dowelled mortice and tenon joints

FIG: 14.6. The secret haunch mortice and tenon

FIG: 14.6. The secret haunch mortice and tenon

FIG: 14.7. Wedged mortice and tenon


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WEEK ELEVEN

11. Making use of metal dogs/fastening and gusset plate

11.1 Gusset plate

Fig: 11.1. 25mm gusset plate

Fig: 11.2. Timber girder truss with gusset plate

Fig: 11.3. Gusset plate in truss roof

Fig: 11.4. Timber king post trusses with gusset

Fig: 11.5. Gusset plate

Fig: 11.6. Gusset plate

Fig: 11.7. Gusset assembly for trusses

11.1.0 Metal dogs

FIG: 11.8. Iron dogs

WEEK TWELVE

12. Construction of wooden floor

12.1 Types of wooden floor

12.2 Method of construction:

12.3 Floor joists suitable for domestic floor loadings

FIG: 12.1: Double floor

FIG: 12.2: Framed floor

WEEK THIRTEEN

13.0.0 Nails, screws and bolts

13.0.1Nnails


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13.0.2 Screws

13.0.3 Raw bolt

FIG: 13.1. Different types of nails

13.1.0 Construction of wooden sills

13.1.1 Window sills

FIG: 13. 2. Construction of window sill

WEEK FOURTEEN

14.0.0 construction of centres for arches

14.0.1 construction

figure: 14.1. segmental arch centre

FIG: 14.2.Costruction of semicircular arch centre

FIG: 14.3. Construction of turning piece

14.1.0 Construction of timber shores

14.1.1 Method of construction

FIG: 14.5. Raking shore

FIG: 14.6. Dead

14.2.0 construction of panel doors

14.2.1 Manufacture of paneled doors

FIG: 14.7. Four panel door

FIG: 14.8. Three panel door

FIG: 14.9. Panel doors

FIG: 14.10. Panel doors

14.4.0 Construction of door and window frame


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14.4.1 Door frames

14.4.2 Window frames.

WEEK FIFTEEN

15.0.0 Construction of simple and built-up roofs

15.0.1 Design of roof

15.0.2 Construction method

FIG: 15.1. Untrussed roofs

FIG: 15.2. Trussed roof

15.1.0 Construction of straight flight of stairs

15.1.1 Setting out one paper

15.1.2 Setting out and construction in workshop

15.1.3 Assembling the parts of stair

FIG: 15.4. Straight flight stair plan

FIG: 15.5. Wooden straight flight stair

FIG: 15.6. Wooden straight flight stair

15.2.0 Construction of door casing

15.2.1 Door casing or lining

15.2.2 Example: assembling and installation of door casing

FIG: 15.7-15.15: Construction of window sill


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WEEK ONE

1. A SKETCH OF SITE LAYOUT SHOWING HOW TO SET OUT A

SIMPLE RESIDENTIAL BUILDING FOUNDATION AND

SUPERSTRUCTURE

1.1SITE PLAN

A site plan is a drawing of your property showing the property lines and any structures that

currently exist on that land (house, garage, fence, etc) and where your proposed addition,

deck, porch, garage, fence, etc is to be located.

Contents of a site plan

A site plan should include:

An arrow indicating north

The scale of the drawing

Draw the site plan to the most appropriate scale, for example, 1 = 10, 1 = 20,

1/4 1.

Property lines For most additions, property lines will need to be physically

located. Additionally, a certificate of survey, signed by a licensed surveyor, will

be required in some cases.

Adjacent streets and any easements.

The distance between buildings and between buildings and property lines.

The dimensions of the existing buildings.

A clear indication of the proposed addition or alteration.

Other appropriate items for your project.

For additions, two copies of the site plan must be submitted. An architectural plan and/or

a structural plan may also be required.


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Site plan review

A site plan review determines compliance with local ordinances and applicable state

building and mechanical codes. This review is done by a city planner. When the planner

gives approval, the next step is to apply for permits.

Projects that usually do not require a site plan review:

Siding, roofs, window replacement, and miscellaneous repairs do not require a site plan

review. Most electrical, plumbing, and mechanical permits also do not require a site plan

review.

Changes to the site plan

After your site plan has been approved, any changes to it must also be approved.

A SITE PLAN is a map of your site. It is drawn "to scale" which means that all of the

real life dimensions are reduced to the same degree. Scales can vary, depending on the

size of your site and the size of your paper. A typical scale for a small site might be 1

inch equals 1 foot. The larger the site, the smaller the scale you would use, such as 1/4

inch equals 1 foot

Why draw a site plan?

A SITE PLAN is a very helpful planning tool. When you are able to see the dimensions

and layout of your site on paper it is much easier to calculate the materials you will need

and to see where different activities can occur. The site plan makes your project portable;

you can carry it in your pocket or mail it. You can make copies. Your planning group can

sit around a table and discuss the project over a copy of the plan.


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1.2 EXAMPLE:Practical to set out site

Tools:

To measure the site:

Tape measure, or measuring "wheel" and a compass to find north.

To draw the plan:

Graph paper, pencils or pens, ruler (or scale.)

HINT: If you don't have a tape measure you can "pace off" the site. This means that you

walk the places you want to measure with even strides, counting how many strides you

took. Then you measure your stride. If your stride is 3 feet long, and you paced twenty

strides along the front of a building, the building is 60 feet long. You can also use your

feet and hands as measuring tools. For example, if you know your feet are ten inches long

you can measure the width of a sidewalk by placing one foot after the other, counting and

multiplying.

When you go out to a site to take measurements and notes, do a "rough draft." You don't

need to draw straight lines or make it neat, just get the information you need.

Measuring

Measure the length and width of the lot, or the portion of the lot you want to work

on.

Locate important built features such as buildings, sidewalks, streets, fences, etc.

and mark them on your plan.

Locate natural features, such as trees, large rocks and water and mark them on

your plan.

Find north. Knowing where north is will be helpful when you want to know how

much sun your site gets. Make a "north arrow" on your plan.


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Drawing

Later sit down with your notes and graph paper and draw your site plan. First draw the

outside edges, or boundaries, of the site. Then put in the other features you noticed, such

as buildings, sidewalks, trees and fences. This is a site plan.

Copying

Make some Xerox copies of your plan so you can draw directly on it and try out a few

different ideas. Pass copies around to get feedback on your ideas and to let others


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FIG.1.1: SITE PLAN SHOWING BOUNDARIES AND ADJACENT

ROADS


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FIG.1.2 : SITE PLAN WITH LANDSCAPING


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WEEK TWO

2. EXECUTION OF FOUNDATION TRENCH AND CASTING

CONCRETE

2.1 TRENCH EXCAVATION

After setting out of building and fixing the profile board, the next operation will be to

excavate the foundations of the building.

For large scale excavation mechanical means are used for digging trenches. Trenches are

the holes dug to receive concrete foundation of building.

When the building is medium size, manual method is employed and the common tools

required here will be diggers and shovels. Excavation should always start from the lowest

side of a site to enable steps be formed incase the site is sloping. Steps enable any volume

of earth removed from a high point of site to be greatly reduced.

Minimum depth of trench should be about 750mm. All earth removed must be packed to

the side. Ensure profile boards are not fully covered up.

The level of the bottom of the trench can be easily checked using spirit level and straight

edge. Ensure that the trench is truly level. Compact hard to ensure that no loose soil is at

the bottom.

Excavation takes various forms depending upon the type of foundation to be laid.

Strip foundation requires the excavation of strip trenches. Pad or isolated foundations

requires holes to be dug where the foundation are to come only, unless connected by

ground beams, while raft and basements needs the excavation of the whole area of the

building, referred to as bulk excavation.


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Excavation in clay, soft chalk or other soils likely to be affected by exposure to the

atmosphere should, whenever practicable, be concreted as soon as they are dug. When

this is not possible, it is advisable to protect the bottom of the excavation with a 75mm

layer of lean concrete blinding, or to leave the last 50 to 75mm of excavation until the

commencement of concreting.

2.2 TIMBERING OF TRENCH EXCAVATION

When trenches are being excavated to a depth likely to cause the caving in of the sides,

they must either be given some form of temporary support or the sides sloped to provide

self support. The support given to the sides of the trench depends upon the depth of the

trench and the soil conditions. Vibration and loads from traffic or other causes, position

of water table, and climatic conditions and the time for which the excavation is to remain

open also affect the decision.

Weak soil requires more elaborate temporary supports. Most temporary support takes the

form of timbering the sides. As timbering is only meant to support the sides of the trench

until all foundation work is complete. Over timbering should always be avoided so that

progress of the work is not hampered in any way

In relatively shallow trenches in firm soil it may be possible to dispense with timbering

or, as it is sometimes termed, planking and strutting. The most that would be required, are

pairs of 17538mm poling boards, spaced at about 1.8m centres, and strutting with a

single 100100mm strut. Alternatively adjustable steel strut may be used.

Most of the timber used for timbering is soft wood, often red or yellow. The various

members required are.


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Poling boards. These are boards 1.00 to 1.50m in length (depending on the depth of

excavation) and they vary in cross-section from 17538 to22550mm.The boards are

placed vertically and abut the soil at the sides of the excavation.

Walings.These are longitudinal members running the length of trench other excavation

and they support poling boards. They vary in size from 17550 to 22575mm.

Struts. These are usually square timbers, either 100100 or 150150mm in size. They

are generally used to support the waling which, in turn, hold the poling boards in

position. Struts are usually spaced at about 1.8m centres to allow adequate working space

between them.

Sheeting.This consists of horizontal boards abutting one another to provide a continuous

barrier when excavating in loose soils. A common size for the sheeting is

17550mm.

FIGURE.2.1. TMBERING IN TRENCH EXCAVATION


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used to set all other pegs in the trench. Pegs are best set along the centre line of the

trench.

Iron pegs are best used but wooden pegs can also be used. Wooden pegs must however

be removed after placing the concrete and before the concrete has hardened to prevent

wood material rotting in the concrete and creating weak points.


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WEEK THREE

3. MIXING OF CONCRETE

3.1 BATCHING

Concrete can be batched by volume or weight.

Batching by volume. This method is usually carried out using an open bottom box called

a gauge box. A 25-kg bag of cement has a volume of approximately 0.02m3.For a 1:2:4

mix a gauge box is filled once with cement, twice with fine aggregate and four times with

coarse aggregate, the top of the gauge box being struck off level each time.

If the fine aggregate is damp or wet its volume will increase by up to 25% and therefore

the amount of fine aggregate should be increased by this amount. This increase in volume

is called bulking.

Batching by weight. This method involves the use of a balance which is linked to a dial

giving an exact mass of the materials as they are placed in the scales. This is best method

since it has a greater accuracy and the balance can be attached to the mixing machine.

Tools required are gauge box, head pan/wheel barrow and shovel/mixer.

3.2 MIXING

Hand Mixing. This should be carried out on a clean hard surface. The materials should

be thoroughly mixed in the dry state twice before the water is added. The water should be

added slowly and mixed at least three times.

Machine mixing. The mix should be turned over in the mixer for at least two minutes

after adding the water. The first batch from the mixer tends to be harsh since some of the

mix will adhere to the sides of the drum. This batch should be used for some less

important work such as filling in weak pockets in the bottom of the excavation.


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FIGURE: 3.1. CONCRETE MIXER FIGURE: 3.2. PLACING OF

CONCRETE

Ready mixed. This is used for large batches with lorry transporters up to 6m3capacity.

It has the advantage of eliminating site storage of materials mixing plant, with the

guarantee of concrete manufactured to quality controlled standards. Placement is

usually direct from the lorry, therefore site- handling facilities must be co-odinated with

deliveries.

FIGURE: 3.3. A MODEL MOBILE CONCRETE MIXER

3.3HANDLING

If concrete is to be transported for some distance over rough ground, the runs should be

kept as short as possible since vibration of this nature can cause segregation of the

materials in the mix. For the same reason concrete should not be dropped from a height

of more than 1m. If this is unavoidable a chute should be used.


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FIGURE: 3.4. A WHEELBARROW

3.4 PLACING

If the concrete is to be placed in a foundation trench, it will be levelled from peg to peg or

if it is to be used as an oversite bed, the external walls could act as a levelling guide. The

levelling is carried out by tamping with a straight edge board. This tamping serves the

dual purpose of compacting and bringing the excess water to the so that it can evaporate.Concrete must not be over-tamped as this will not only bring the water to the surface but

also the cement past which is required to act as matrix. Concrete should be placed as soon

as possible after mixing to ensure that the setting action has not commenced. Concrete

which dries out too quickly will not develop its full strength; therefore new concrete

should be protected from the drying winds and sun by being covered with canvas, straw,

polythene sheeting or damp sawdust. This protection should be continued for at least

three days since concrete takes about twenty-eight days to obtain its working strength.

3.5 SPECIFYING CONCRETE

Concrete can be specified by any of the four following methods.

Designed mix. The mix is specified by a grade corresponding to required characteristic

compressive strength at 28days.There are 12 grades from C7.5 to C60, the C indicates the

compressive strength in N/mm2or MPa. Flexural (F) strength grades may also be

specified as F3, F4 or F5 i.e. 3, 4 or 5 N/mm2. Also the requirement must specify the

cement and aggregate content and maximum free water/ cement ratio.

Prescribed mix. This is a recipe of constituents with their properties and quantities used

to manufacture the concrete. The specification must be made for.

The type of cement


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Type of aggregates and their maximum size

Mix proportions by weight

Degree of workability

Prescribed are based on established data indicating conformity to strength, durability and

other characteristics.

Example.

1:3:6/40mm aggregate.

1:2:4/20mm aggregate.

Standard mix. Mixes are produced from one of five grades, ranging from ST1 to ST5,

with corresponding 28 days strength characteristics of 7.5 to a limit of only 25N/mm2.

Mix compositions are specified as in prescribed mix.

These mixes are most suited to site production, where the scale of operations is

relatively small. Alternatively, they may be used where mix design procedures would be

too time consuming, inappropriate uneconomical.

Design mix. This mixes are selected relative to particular applications and site

conditions, in place of generalizations or use of alternative design criteria that may not be

entirely appropriate. Grading and strength characteristics are extensive and vary with

application.

General (GEN), grade 0-4, ranging from 7.5 to 25N/mm2characteristic strength. For

foundations, floors and external works.

Foundations (FND), graded 2, 3, 4A and 4B with characteristic strength of 35N/mm2.

These are particularly appropriate for resisting the effects of sulphates in the ground.

Paving (PAV), graded 1 or 2 in 35 or 45N/mm2strengths, respectively. A strong

concrete for use in driveways and heavy duty pavings.


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Reinforced (RC) and prestressed concrete grade 30, 35, 40 and 50 corresponding with

characteristic strength and exposures ranging from mild to most severe.

Quality control is of paramount importance in this mix. Therefore, producers are

required to have quality assurance product conforming to BS EN ISO 9001.

3.6 EXAMPLE:

Prepare mixing bay by mixing and spreading weak concrete to form mixing slab on

which the materials are mixed. Before this, the materials i.e river sand called fine

aggregate and gravels called coarse aggregates are stored on clean surface.

The mixing slab is then set out and the concrete mixed, placed, properly compacted and

leveled. The materials are then carefully measured using gauge box, head pan or any

suitable container are placed on the slab. The cement is then mixed with the material

before adding water.

Suitable mixes for different jobs are:-

1: 3:6 - Mass concrete

1:2:4 - Reinforced concrete

Reinforced concrete is any concrete with reinforcement for additional strength.

For manual mixing, first measure the fine aggregate and mix dry with the cement

thoroughly according to the job. Spread the material and spread coarse aggregate all over.

Mix about two times dry. Then add water and start mixing thoroughly, at three times.

For mechanical mixing, first measure and poor the fine aggregate into the mixer, add the

cement required and mix for about two minutes. Ensure thorough mixing. Add coarse

aggregate and thoroughly mix before adding water. Finally mix and serve. Clean all tools

and equipment at the end of work.


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PLACING AND COMPACTING OF CONCRETE FOUNDATION

Concrete shall be thoroughly mixed on clean hard surface or using mechanical method

before placing.

The tools required when placing include shovels, trowels, wooden or iron rammer or

mechanical rammer, straight edge, wheel barrows, head-pans or mechanical dumpers.

Concrete must be carefully transported from the mixing point to the trench to prevent

separation of the coarse aggregate, fine aggregate from the cement which is known as

segregation. Using two men for mixing, six labourers with head pans and either one or

two with wheel barrows, the foundation project for a simple building can be completed

within a short time.

Place and spread the concrete. When it has reached or covered the required depth, the

rammer or poky vibrator is used to compact the concrete. The straight edge can also be

used to ensure true surface. After twenty-four hours, the member should be cured by

wetting it with water to Ensure strength development.

Students are required to write a report on concrete mix, handling, placing and

compacting.


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WEEK FOUR

4. SETTING OUT OF A SIMPLE RESDENTIAL BUILDING BLOCK

WALL SUPER STRUCTURE

After laying the foundation concrete, wall construction commences according to the

setting out plans. The common tools required for wall construction include:

- Trowel - Tape

- Spirit level - Straight edge

- Line - Head pan

- Batten - Shovels

- Steel square- Cutting axe

The types of blocks used for wall construction are:-

- 225 x 225 x 450 = for erecting external walls

- 150 x 225 x 450 = For erecting external walls and partitions

- 100 x 225 x 450 = For erecting partition walls only

- 102.521560 brick = For erecting external and partition walls

- Other decorative blocks are required for fancy work only.

The most important aspect of block-laying are:-

- Lining = straightness of wall

- Level = true horizontal surface

- Plumbing = true vertical surface

To set out the corner walls,

- Set up lines, along the wall lines from the profile boards either from the internal

or external part.

- Spread mortar (mixture of cement and sand only) at the corner points.


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- Use straight edge and spirit level to plumb down the line and mark on the mortar.

- Place the block and check against the line using same tools.

- After ensuring proper setting of the blocks at the corners, level them and erect two

or three layers at each corner and partitions. Fill the joints properly.

- Stretch line in-between the corner blocks and set the straight line blocks to fill the

spaces. Ensure the blocks are truly straight and level. Lines can be used both at

the top and sides of the wall during the block-laying to ensure true level and

plumb of the block wall, The spirit level bubble must always be in the centre of

the glass and likewise bubble must also be at the centre for true plumb line. i.e

true vertical alignment of the blocks

- The walls should be properly set up and erected in the trench; this is erected up

until the building is out of the trench.

- The blocks should be taken out of the ground at least 150mm above the ground

level. This level represents the ground floor level.


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FIGURE: 4.1. SETTING OUT OF BLOCK WALL SUPERSTRUTURE

Students are required to write a report on how to set out a block wall

superstructure.


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WEEK FIVE

5.PLUMBING OF PIPES FOR WASTE WATER AS DRAINAGE

5.1 SYSTEM OF DRAINAGE

SEPARATE SYSTEM:

In these systems, the rainwater is kept separate from the foul water from the house. The

rainwater is collected and either discharged into water tanks to be used later or discharged

into water course. The system can be of great benefits In areas where rainfall is scanty.

COMBINED SYSTEM

This is an alternative system whereby water from roofs and paved areas together with the

effluent of sanitary fittings are collected together and discharged into a sewer. The

advantage of this system is that, the storms water gives an effective flushing to the drain.

5.2 CHOICE OF PIPES

All the pipes are suitable for use below ground, but the strength of a pipeline may

become a limiting factor under loading conditions. In these situations ri.gid pipes with

flexible joints should be used, and short lengths pipe in ground subject to severe

settlement. Where pipes are laid above ground, special attention should be paid to

structural support and protection against mechanical damage, frost and corrosion.

Rigid pipes.Vitrified clay pipes. Manufactured to Bs65 and 540 with nominal bores of 75

to 900mm and lengths of 300mm to 1.50m. Clay pipes are resistant to attack by wide

range of substances, both acid and alkaline. It is very popular although the traditional

joint made of two rings of tarred yarn and with socket and spigot filled with cement

mortar is increasingly displaced by mechanical or flexible joints. This is liable to damage

by settlement. Further more the short pipe lengths produce a larger number of joints.

Concrete pipes. These are suitable for use with normal effluents but may be attack acid

or sulphate in the effluent, or in the surrounding soil. Concrete pipes are used mainly for

large pipes of 225mm diameter and upwards, and with these sizes external wrappings of

glass-fibre laminate are available which reinforce the pipe and protect them from external


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attack. Concrete pipes to BS 556 are supplied either reinforced or unreinforced in lengths

of 900mm to 5m. Prestressed concrete pipes are also available complying with BS 5178.

Asbestos cement pipes.These are made to BS 3656. They are used for drainage

purposes and have the same shortcoming as concrete pipes.

Cast iron pipes.These can be supplied with spigot and socket joints to BS 437 for

caulking with lead or a proprietary material, or as pressure pipes with flexible joints to

BS1211, which are more much more satisfactory for use in difficult or waterlogged

conditions or ground subject to large movement. The coating on these pipes gives good

protection against corrosion and a reasonable life with average ground conditions and

normal effluents. They can be laid at any depth on account of their great strength. Cast

iron pipes are made in varying lengths, but the most commonly used length is around

3.6m. Ductile iron pipes are covered by BS 4772.

Flexible pipes. Pitch-impregnated fibre pipes. Made to BS 2760, they are becoming

increasingly popular due to their suitability for use with normal domestic and most trade

wastes.

They are manufactured in nominal bores of 50 to 225mm and standard lengths are 1.7,

2.5 and 3m. They are more economical than clay pipes where long lengths are involved

and in bad ground conditions.

Unplasticised PVC pipes. Manufactured to BS 4660, they are 110 and 160mm nominal

sizes and are golden brown in colour. They are suitable for domestic installations and

surface drainage. UPVC pipes are available in 1, 3, and 6m lengths. They should not be

use for effluent at high temperatures and they become brittle at low temperatures and

therefore handling with care. They are light in weight.

Reinforced plastic pipes. These are made of thermosetting resin and have advantages of

light weight and resistance to corrosion and effluents with high temperature.

5.3 SETTING OUT OF DRAINAGE SYSTEM


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The setting out of the trench is much simpler than setting out for building foundation,

because the drain line follows a straight course as much as possible. Sight rails pegs and

travelers are needed for the setting out operation. Travelers are T-shaped wooden tools

used in a similar way to boning rods.

The centre line of the drain pipe is marked out by wooden pegs driven into the ground

starting from the building outlet. A rail, which is a horizontal piece nailed to two vertical

member, is erected across the trench at the position of the first manhole or inspection

chamber near the building. The height of the rail is fixed at a suitable known level above

the invert level of the pipe. The positions of inspection chambers are then marked out

along the line by driving four pegs into the ground.

Excavation can commence after the setting out. Shallow trenches in firm soils up to 1.3m

deep do not need supports. The trench is excavated to constant fall from the building. To

ensure that this is done, a series of traveler are placed at the bottom of trench and the top

sighted to the sight rail. The length of the vertical piece of the traveler is the same as the

height of the sight rail measured from the invert level of the pipe.

The rails are erected at the inspection chamber positions or at changes of direction. This

gives an acceptable gradient. The sighting of the travelers is done from the lower rail

through to the upper one. The pipes are kept in a straight line by means of a line stretched

from one inspection chamber to the next.

5.4 LAYING OF PIPES

Rigid pipes must have an even bed laid to the required slope, this bed is usually 150mm

thick concrete. The bed is to prevent the pipes fracturing when the trench is backfilledand compacted.

In less important jobs, a concrete bed may not be necessary, especially if the ground is

firm and stable. A well consolidated earth bed is all that is required, but the back filling

and compacting should be done with a lot of care.


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A concrete bed is not required by the regulations for cast iron pipes and where its

provided, a 100mm thick is sufficient.

5.5 JOINTING OF PIPES

The jointing of pipes made with sockets and spigots is achieved by inserting the spigots

into the socket caulking with tarred hemp or yarn and then making the joint with 1:1

cement and sand mortar.

Where this type of joint is used, the drain must not be tested until the cement has gained

sufficient strength. This period should be at least twelve hours after jointing. The purpose

of caulking the joint with yarn is to centre the spigot in the socket and to prevent mortar

falling into the bore of the pipe during the process of jointing.

Cast iron pipes are jointed by inserting a ring of yarn or lead wool into the jointing space

and then running in molten lead and caulking. A flexible joint can be obtained by using a

rubber ring.

PVC jointing methods use pre-formed socket or loose couplings, and this is made by a

rubber ring or using a solvent and adhesive. Pitch fibres pipes are jointed by means of

external couplings in polypropylene. Asbestos cement pipes also have tapered ends which

are joined using coupling and rubber rings.


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FIGURE: 5.1. COUPLINGS AND VENTS

5.6 DRAINAGE TEST

Drains can be tested in three ways. These include:

Hydraulic Test

This is the most reliable method of testing drains. The test is performed by blocking

the lower end of the section of drain to be tested by inserting an expanding plug or

air flatted bag and then filling the portion of the system with water up to the level of

the gullies which should also be plugged or stopped with one of the devices made

specially for this purpose. The filling of water is carried out by attaching one end of a

length of rubber tubing to the nipple of the drain stopper or plug at the upper end and

connecting the other end to a container holding water at the required head. 600mm

head of water should be removed when applying this test.

A leakage is indicated by a drop in the leveled water in the container, and the drain

pipes are covered. The points of leakage are easily noticeable.


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Fifteen minutes should elapse before the water level is observed to allow for any

absorption that might take place.

Smoke Test

This test is performed by forcing air- laden smoke into the section of the system

under test from a special smoke box, the smoke is produced by burning oily waste in

the smoke box. The smoke is forced through the lower end of the drain and vent

pipes. Soil pipes as well as traps should be left unsealed until the smoke emerged

from them, this ensured that the drain under examination is full of air laden smoke.

A few strokes of the bellows of the smoke machines will set up a slight pressure in

the system and the dome over-the smoke box should rise and remain in the position

if there are no leakages

The advantage in this system is that any smoke escaping through a leakage is easily

visible.

Air test

This test is particularly suitable for soil pipes. Plug all soil and vent pipes and

gullies. The air is then pumped into the drain through a T-piece air pipe and one arm

is attached to one of the stoppers as in water test. The other arm is connected to u-

gauge containing water. The rubber tubing may be made to pass under a water seal

instead of connecting to a stopper.

When the pressure is applied, the water in one arm of the gauge will be depressed

and the other elevated. The difference in level of the water will register the head

pressure and if the water in the gauge remains still, the drain is satisfactory. A fall

indicates leakage. The disadvantage of the air test is that the point of leakage is not

easily detected as in the two previous tests


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FIGURE: 5.2. DRAINAGE SYSTEM


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WEEK SIX

6. LAYING OF BLOCKS/BRICKS IN DIFFERENT BONDS

To build or construct a wall of brick or blocks, it usually follows the pattern of laying

the bricks or blocks In some regulation arrangement. The brick /blocks courses or rows in

a wall are arranged to ensure that each brick/block overlaps or bear upon two or more

bricks / immediately below it. The process of laying the bricks across each other and

binding them together is called bonding. The amount of overlap and the part of the brick

used determine the pattern or bond of brick work.

6.1 PURPOSE OF BONDING

The main purpose of bonding is to provide maximum strength, lateral stability and

resistance to side thrust, and it distributes vertical and horizontal load over a large area of

the wall. A secondary purpose of bonding is to provide appearance (decoration).

6.2 CHOICE OF BRICK BOND

The choice of any brick bond defends on the following factors.

1. Prevailing environmental or site conditions.

2. Thickness of the wall.

3. The purpose for the wall construction i.e either strength or decoration

6.3 CHOICE OF MORTAR.1. Cement and sand mortar (1:4). This is use for load bearing wall and water works

2. Lime, cement and sand mortar (1:1:4, 1:1:6). This use for building construction

work.

6.4 PRINCIPLES OF BONDING OF BRICKWORK

1. The correct lap should be set out and maintained by introduction of:

(a)A closer next to the quoin header.

(b)A three-quarter bat starting the stretcher course.

2. There should be no straight joints in a wall.

3. The perpends or cross-joints in alter courses should be kept vertical.

4. Closer should never be built in the face of the wall except next to the quoin

header.


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5. The tie bricks at junctions or quoins should be well-bonded to secure the walls

together.

6. The bricks which are laid in the interior of thick walls should be laid header wise

as far as possible.

7. Sectional bond should be maintained across the wall, that is, the bond on the back

should be in line with the bond on the face side of the wall.

8. To achieve the maximum strength in a wall, all the joints in the interior of the

wall should be kept filled or flushed in with mortar in every course. This can be

done by mixing a quantity of mortar to a grout or slurry and running it into the

joints between the bricks which have been laid in the wall.

6.5TYPES OF BOND

STRETCHER BOND: This consists of all bricks laid as stretchers on every

course with the courses laid half-bond to each other; this is affected in a plain wall

with stopped ends by introducing a half-bat as the starting brick to alternate

courses. Usually only used in walls of a half-brick in thickness.

FIGURE: 6.I. STRETCHER BOND

ENGLISH BOND:This consists of alternate courses of headers and stretchers

with a closer placed next to the quoin header to form the lap. There is, however, a

variation where a closer is not used in the header course, and the lap is formedby


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starting each stretcher course with a three-quarter bat. Such variation is not very

common. It is considered one of the strongest bonds. It is suitable for the

construction of load-baring walls and for places where strength is of utmost

importance.

FLEMISH BOND: This consists of alternate headers and stretchers, with the

headers in one course being placed centrally over the stretcher in the course

below. A closer is placed next to the quoin header to form the lap. Flemish bond

is said to give a more attractive face appearance than English bond as it appears

less monotonous. It affords a saving in facing bricks because of the header.

English bond requires approximately eighty-nine facing bricks per square metre,

while Flemish bond requires only seventy eight facings. The header face of

many bricks is dark, and they are separated in this bond as against the English

where they are continuous.

FIGURE: 6.2. ENGLISH BOND


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FIGURE: 6.3. FLEMISH BOND

HEADER BOND:In this bond the arrangement shows the header face of every brick,

with 215 mm thickness. The bond is formed by three-quarter bats at the quoin. It is rarely

in use, because it has now attractive finish (too many joints). It is used in footing courses

or walling curved on plan.

FIGURE: 6.4. HEADER BOND

Garden Wall Bond: This is designed to reduce the number of header faces to facilitate

a fair finish both sides in walls where appearance is important. There is one course of

header bricks to every three courses of stretchers in English garden wall bond, and one

header to every three stretchers in each course of Flemish garden wall bond.


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FIGURE: 6.5. BRICK BONDS

6.6 SETTING OUT BONDS

In some cases it may be difficult to apply the standard patterns to the quoin, junction

walls and stopped ends. The reason is that consistency of bonding is impossible to

maintain. For example when setting out English and Dutch bonds for walls of 1 and 2

bricks in thickness, the pattern is the same on both faces, whereas on one 1 1/2 and 21/2

brick walls the pattern is different. That is headers on one face and stretchers on the other.

Any rules concerning bonding can be applied as far as practicable. A general rule for

quoins, stopped ends and junction walls in English and Dutch bonds is that where a wall

changes direction, so the bond will also change, that is if there are stretchers on one face

then the adjoining face will be headers. This is however , cannot be applied in every case,

as in a 11/2

-brick junction wall adjoining a 2-brick such as 1 and 2 bricks in thickness. There must

be two adjoining faces having similar bonds.

One rule, however, should always be applied. When setting out quoins or junction walls,

care should be taking to ensure correct trying in the walls at the internal angles to achieve

the maximum resistance against cracking due to shrinkage or uneven settlement.

Quoins


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The bonding arrangements to quoin vary according to the bonds which are used and the

sizes of the walls comprising the corners.

FIGURE: 6.5. A BRICK WALL


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WEEK SEVEN

7. IDENTIFICATION OF CONSTRUCTION WOOD TYPES AND

THEIR SIZES

7.1 CONSTRUCTION WOOD TYPES:

Timber is divided into two classes: The coniferous trees, known as softwoods, and the

deciduous trees, known as hardwoods. A tree consists of three main parts: the stem, and

the crown. The root fixes the tree in the ground and takes in moisture form the soil. The

stem or trunk stores food-stuffs, conducts these to the leaves and provides strength and

rigidly to the tree. Te timber which man has used since the earliest ages is, of curse, cut

form the trunk. The crown consists of branches, twigs and leaves in which the chemical

process essential t growth takes place.

Softwoods: These are usually evergreen with needle-pointed leaves and are cone-bearing.

Hardness trees have board leaves, which in most cases are shed at the end of the growing

seasons. There are certain exceptions, one example being the holly tree which is

evergreen throughout the year.

A tree consists of three main parts: the stem, and the crown. The root fixes the tree in the

ground and takes in moisture form the soil. The stem or trunk stores food-stuffs, conducts

these to the leaves and provides strength and rigidly to the tree. Te timber which man has

used since the earliest ages is, of curse, cut form the trunk. The crown consists of

branches, twigs and leaves in which the chemical process essential t growth takes place.

Hardwoods: These bear fruit in which the seeds are to be found, the chestnut of the

horse-chestnut, the acorn of the oak, and the berries of the holly tree are examples.

The terms softwood and hardwood are by no means accurate in every case; they are

however, generally descriptive and established terms in the trade. Some hardwoods are as


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soft as, or even softer than, the nominally softwood, whilst some softwoods are harder

than many hardwoods.

Most of the timber used by the carpenters and joiners in the construction of building is

softwood. This is mainly of the pine and fir class, and through they are to be found in

many parts of the world, the chief sources of pine are the forest of Canada, North

America, Scandinavia, and Russia. The forest belts providing the hardwoods are to be

found in the tropical zones, namely: central and south America, West Africa, regions of

India, Burma, and Malaya and Eastern Australia.

Advantage of Wood

Wood has the following advantage:

i. Very high strength compared to its weight

ii. Easily worked and shaped

iii. Easily erected, dismantled, and modified to suit changing conditions

iv. Warmth to the touch and richness and variety in natural colour an texture

v. Wide variety of species to suit differing requirements

vi. Good thermal insulation

vii. High fire endurance-does not suddenly lose its strength, distort, or expand and

thus increases the time for escape, salvage, and fire-fighting.

The timber expert has to know many more than those given, and he h as to be able to

identify the family, group, species, and variety. General appearance, texture, colour,

smell, weight, etc, are useful I distinguishing different kinds of timber, but identification

is more reliable if it is based on the structural features of the timber. For this purpose a

hand magnifying glass or microscope is necessary to examine samples of the timber,

specially cut with a sharp knife as shown in or by a machine called a microtome.

Structure

Softwood timber is composed of many tubular cells cemented together called tracheids,

these have wall of wood substance and the rising sap passed from one tracheid to anther


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thought the softer texture within the cell walls, known as pits, A parts from transporting

the moisture drawn up from the roots, the trachelds in the structure of softwoods give

strength to the tree.

A further series of cells, termed parenchyma rays, pass from the outside of the tree

towards the pith and are formed of a pity substance. These cells, which are shorter than

the tracheids store reserves of food which can be passed to any part of the tree which

requires them. The rays are often used as a means of identifying timbers. Resin canals

sometimes occur in softwoods. These are placed in a horizontal ad vertical direction.

The structure of hardwoods is more complicated than that of softwoods. The main feature

of the structure is the presence of large cells or vessels which pass the moisture up the

tree from the roots to the leaves. Along with the large vessels are rays parenchyma cells

and fibres. The latter serve to give strength to the tree.

There are two types of hardwoods: Ring-porous, and diffuse-porous, In ring-porous

timbers large cells are produced during the early part of the growth ring and these

become smaller in size as the season progresses. In diffuse-porous timbers the cells are

generally the same size within the growth ring.

Annual or growth rings

These are formed by the early spring-wood and are arranged in roughly concentric

formation round the pith, as each growing season an additional sheath of tissue is

produced around the tree, increasing the diameter and pushing the bark outwards. In

softwoods which have been grown slowly, the timber will have more growth rings than

one which as been grown quickly, resulting in much stronger timber, the age of a tree can

be determined by counting these rings of annual growth.

There are many more large cells and fewer fibres in a slow-grown ring-porous hardwood.This means that a weaker timber is produced than is the case with hardwood which is

fast-grown.

Medullary raysThese exist in all woods. They are seen as lines or the transverse section,

radiating form the pith to the bark and running with the grain of the tree. Generally, these


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rays are not easy to see without the use of a lens or microscope, except in certain

hardwoods, particularly oak. It is these rays which give many hardwoods their rich

decorative figuring.

Sapwood and heartwood

New wood formed on the outside, next to the bark, is called sapwood. Every part of

wood in any tree has, therefore, been sapwood at some time. As this contains all the

food-stuffs, it is liable to

attack from fungi or insect for this reason. Sapwood, properly treated, can be made

immune from such attack, and should not be discarded on this account

.

Heartwood, is the growth of earlier years and is the inner portion of the tree trunk. It is

darker in colour and the more mature wood. It serves mainly to give strength to the tree

trunk.

FIGURE: 7.1. INTRENAL STRUCTURE OF WOOD


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Pitch

This is centre of the tree and represents the fist growth Bark

This outer covering of corky tissue serves to protect tree against external injury and

extremes of temperature. The outside of the bark is termed the cortex and that betweenthe cambium layer and the cortex, the bast.

It is not proposed to consider the chemical component of tree in detail here. It may be

sufficient to indicate that cellulose is the chef structural component contained in the cell

walls, while resins, colouring matter, alkaloids, tannins, etc. are other substance to be

found.

Grain

This term is very loosely when applied to timber and should not be confused with its

texture. Grain refers to the direction of the fibres and other woody elements, while texture

refers to the arrangement, fineness or coarseness, and distribution of these elements.

Thus, fine textured timber has element which are small and close together. When they are

larger an spaced wider apart the term coarse in applied.

Straight grain refers in timber where the fibres are parallel with the surface; such timber

is relatively strong and easy to work. Cross grain is a deviation of the fibres of ht timberfrom a line parallel to the edges of the wood. Diagonal-grained timber is a result of

improper conversion so that fibres are inclining to the edges of the timber; this reduces

strength and is sometimes referred to as oblique grain. Spiral-grained timber has fibres

which take a more or less spiral course in a particular direction. Interlocking grains as

fibres partly-spiraling which are in-clined in opposite directions and are often known as

wild grain. Curly grain and wavy grain indicates wave-like stripes on the surface of the

timber due to the fibres changing direction, and is valued because of it highly decorative

appearance. Short grain indicates that the timber may fracture due to fibres lying in a

certain direction. End grain refers to the section of a cross-cut surface, showing the

arrangement of the exposed fibres.


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Figure is the pattern on the surface of the timber and is due entirely to the structure of the

wood. Straight-grained timber has only a plain figure whereas wavy or interlocked-

grained timber produces a finely marked and attractive figure.

The method of conversion affects the nature of the figure. Quarter sawing in the case of

oak used for such purpose as paneling and furniture, where appearance is most important,

discloses on the surface the medullary rays which gives the silver grain or rich figure.

A compete list of commercially used timbers is outsider the scope this book, but the

following short descriptions are of varieties in extensive use. The standard name of the

timber is given first, followed by alternatives.

FIGURE: 7.2. SAWN WOOD

Softwoods

Douglas fir (British Columbian pine, Oregon pine) average weight 528.66kg/m3.

available I logon lengths and large sections; straight-grained and resilient: easy to work

by hand or machine. Reddish brown to pinkish brown in colour. Being one of the hardest

softwood it can take heavy, continuous wear. The strongest, for its weight, of any

softwood in the world, with a high resistance to acids and decay, has good gluing an high


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insulation qualities. Used of first-class joinery. Large quantities of plywood are made

from Douglas fir.

Hemlock, western

(pacific hemlock, British Columbian hemlock) average weight 480-60kg. It ranks high in

strength and durability and has a fine uniform texture. Straight-grained, stiff yet easily

worked, and light brown in colour. Easy to work by hand or machine and good for

gluing. Its smooth clear surface takes stain, paint, and varnish without difficulty used for

interior journey work, built-in furniture, agricultural and timber buildings.

Larch, Europeanaverage weight 592.74kg/m3. one of the most valuable and most used

home grown timber reddish brown in colour, very strong and durable; resinous; straight-

grained. The larch grown to a height of 30-48m or more, with a girth of 4-570m in some

trees. Used for all kinds of carpentry work, fencing gates, posts, garden furniture,

flooring, and railway sleepers.

Parana pine average weight 544-68kg/3. This South America softwood had an even

texture and is straight-grained. It is unsuitable for exterior work, being brittle and mot

durable. The colour is from light to darkish brown with some reddishness. Suitable for all

classes of interior joinery but is inclined to split on nailing. Takes screw, glue, and paint

well.

Hardwoods

Afrormosia (kokrodua) average weight 688-86kg/m3 . This wood resembles teak in

appearance, but has a finer grain. It is very durable and well. it is suitable for high-class

joinery, ship and carriage work. Care should be taken when use on outside work in direct

contact with ironwork to avoid staining.

Agba (Nigeria cedor, pink mahogany) average weight 480-60kg/m3. this West African

timber grow up to 60-960m in height.

American whitewood (canary whitewood, yellow poplar) average weight 528-66kg/m3.

Essentially a wood for interior work to be painted. It takes glue, nails an screws well and

is easy to work. Ther tree grow to a height of 45.700-60.960m and up to 3.048m in


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diameter. The colour varies according to the age of the wood, between quite yellow and

grey, it is not particularly strong and will deteriorate quickly in damp situations.

Botanically whitewood is a hardwood, but in workability it is to all intents and purpose a

softwood.

Beech, European average weight 720-kg/m3. This is one of the most used hardwood in

this country, large quantities being imported form central and southern Europe. The

timber is hard, close-grained and durable, with a fine texture. It is used extensively for

furniture. Particularly chair-making wooden planes, handles of the woodworker saw other

tools, block and parquets flooring. It shows silver grain and is used for veneers on this

account. Colour reddish yellow or light brown.

Birch average weighty 672-90kg/m3. From Europe generally, also Canada and other

regions of North America. European birch is used principally of plywood. Large

quantities form Finland and Sweden are imported into this country. Colour white to light

brown. Straight-grained and medium texture. Similar to beech in many ways but is more

inclined to warp.

Black bean average weight 720-90kg/m3. chocolate brown with greyish brown streaks

giving an attractive rich appearance to the wood. Similar to French walnut in colour, hard

to work. For new south Wales and queensland, the timber is excellent for veneers high-

class joinery, paneling and furniture.

7.2 COMMON SIZES OF TIMBER

253003600

503003600

50503600

50753600

501503600

1001003600


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10. Drilling machine (Table and pillar).

11. Sanding machine.

12. Spraying machines.

13. Grinding machine.

14. Router machine.

15. The lathe machine

16. Blower.

17. Bracing machine

18. Presser.


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It is very difficult is get a perfect layout for the machines and benches in a workshop

because of the varying nature of the work they are used for. It is a good plan, however, to

arrange the machine in the following groups: first, the cutting-off machines (cross-cut

and rip saws), next the planning machines (surface planers, thickeners, and four sides),

then the jointing and finishing machines (mortising, tenoning, and moulding machines,

belt, drum and disc sanders). The joiners shop should be near the finishing machines so

that there is no unnecessary waste of time when work is carried operations.

Small workshop layout

Two typical layouts for a small workshop employing about eight men are given. The first

example show the machines shop equipped with one general woodworking machine, one

mortise machine, and one band saw. The joiners shop contains three double benches,

with assembly and storage space provided at the end of each bench. The foreman the

bench nearest to the office.

It the second example the machine shop contains six machines a cross-cut saw, a rip saw,

a planer and thicknesser, a mortise machine, a spindle moulder, and a band saw. The

joiners shop has two double benches and a single setting-out bench which is placed near

the office. The single bench would again probably be occupied by the foremen.


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FIGURE: 9.1: STARNDARD CAPENTRY AND JOINERY WORKSHOP


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FIGURE: 9.2: STARNDARD CAPENTRY AND JOINERY WORKSHOP


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9.2 EXAMPLE: 1

An example is the layout of medium-sized joinery workshop employing about thirty-six

men and housing sixteen woodworking machines and eight double benches.

FIGURE: 9.3: STANDARD CAPENTRY AND JOINERY WORKSHOP


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FIGURE: 9.4: STANDARD CAPENTRY AND JOINERY WORKSHOP


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WEEK TEN

10. PREPARATION FOR JOINTS IN WOOD WORK

There are many different joints that the carpenter and joiner may use. Joints generally fall

into three categories and carry out the following functions:

CATEGORY JOINT FUNCTION

Lengthening End To increase the effective length

of timber

Widening Edge To increase the width of wood

or

Manufactured boards

Framing Angle To terminate or to change

direction

10.1 TYPES OF JOINTS

An example of timber Joints are; Halved joints, bridle joints, mortice and tenon,

dowelled and wedged mortice and tenon joints.

Halved Joints: In this type of joint one piece crosses over the other.


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FIGURE: 10.1.HALVED JOINT

FIGURE: 10.2.HALVED JOINTS


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BRIDLE:

These two bridle joints are used when a light frame is needed. for example, a

picture frame. One part of the joint fits into the other part and is glued

permanently in position.

FIGURE: 10.3. BRIDLE JOINT

MORTICE AND TENON JOINTS:

Below are two examples of mortice and tenon joints: These are used when making tables

or cabinets and they are very strong when glued together. There are many different types

and a larger feature on this type of joint appears below.

FIGURE:10.4. MORTICE AND TENON JOINT


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when it is under great pressure. This is used as a joint on chairs and other pieces of

furniture so that the joints do not break apart when extra weight is applied.

This is another way in which dowels can be used to form a joint. Modern pieces of

furniture are often jointed in this way. It is a permanent method but it is not the strongest

joint as the parts can eventually pull apart, especially as the joint becomes old. Modern

glues that are very strong have meant that this joint is often used to quickly fix parts

together.


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FIGURE: 14.6. THE SECRET HAUNCH MORTICE AND TENON

THE SECRET HAUNCH MORTICE AND TENON:

If the mortice and tenon joint is to used as part of a frame, a secret or sloping haunch is

used. The tenon does not show on the outer side of the joint and it gives greater gluing

area, adding to the overall strength of the joint.

FIGURE: 14.7. WEDGED MORTICE AND TENON

WEDGED MORTICE AND TENON:


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This is a very strong and attractive joint. The tenon has two slots and when it is pushed

into the mortice wedges are tapped into position. The wedges hold the joint together

firmly and they also give the joint an interesting look.

10.2 EXAMPLE: 1

MAKING A MORTICE AND TENON JOINT - THE MORTICE

The construction of a plain mortice and tenon joint is shown. This type of joint has a wide

range of uses and is particularly useful when manufacturing furniture. Several types of

mortice and tenon joint exist. The marking out and cutting of all the mortice and tenon


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joints are based in this simple joint. Below is a stage by stage account of the marking and

cutting of the mortice part of the joint.

The mortice gauge is a special type of marking gauge and it is used to mark wood so that

a mortice can be cut into it. The diagram to the above represents a typical mortice and

tenon joint. The mortice is marked out using the mortice gauge although it must be set to

the correct size of mortice chisel very carefully. A mortice chisel is then used to remove

the waste wood.

The mortice gauge is normally made from a hardwood such as rose wood with brass

being used for the parts that slide along the stem.

Animated Mortice Gauge

MARKING OUT A MORTICE

STEP ONE: 1

The distance between the fixed spur and the adjustable spur is set

so that it matches the width of the mortice chisel. The width of the

mortice chisel should match the width of the mortice to be cut in thewood.

STEP TWO:


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A try square and a marking knife are used mark the lines at the top and bottom of the

mortice.

STEP THREE:

The stock of the mortice gauge is pressed against the side of the

wood. It is then pushed along the wood until the mortice is

marked out correctly.

STEP FOUR:

The mortice chisel is then used to

break the surface of the waste wood

by gently tapping the handle with a

mallet.

STEP FIVE:

The waste wood is then slowly removed,

this time, by applying more force to the

handle of the chisel with the mallet. The

waste is removed until the entire mortice

hole has been cut.


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Remove waste wood with a chisel

Level the bottom of the trench with router.

Test for fitness by putting the pieces together and removed.

Prepare final fixing and dress up using slicing or smoothing tools.

Students are required to write a report on joints in woodwork.


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WEEK ELEVEN

11. MAKING USE OF METAL DOGS/FASTENING AND GUSSET

PLATE

11.1 GUSSET PLATE

FIGURE: 11.1. 25MM GUSSET PLATE

FIGURE: 11.2. TIMBER GIRDER TRUSSWITH GUSSET PLATE

FIGURE: 11.3. GUSSET PLATE IN TRUSS ROOF


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FIGURE: 11.4. TIMBER KING POST TRUSSES WITH GUSSET


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FIGURE: 11.5. GUSSET

PLATE

FIGURE: 11.6. GUSSET PLATE


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FIGURE: 11.7. GUSSET ASSEMBLY FOR TRUSSES


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WEEK TWELVE

12. CONSTRUCTION OF WOODEN FLOOR

12.1 TYPES OF WOODEN FLOOR

SINGLE FLOOR: When bridging joists are used to support floor board and the joist in

one continuous length that span from wall to wall is known as single floors. These types

of floors are generally use in domestic buildings and offices of supervisors in

manufacturing companies. The maximum economic span should be about 4.5m long.

Two members are used in constructing the floor:

I. Joist 150mm by 50mm thick or 75mm thick

ii. Floor board 25mm thick

DOUBLE FLOORS: Double floors are rarely used in modern building practice.

The maximum clear span for softwood bridging joists can be considered as 4.8m, and

when the smallest plan dimension of a room exceeds this length it is necessary to

construct a double floor. Here relatively large members, called binders, are introduced to

given intermediate support to the joists.

Frame floors. When the shortest span of the room exceeds 7.2m it is necessary to

constructs a framed floor. This consists of bridging joists, binders, and girders. It is now

common practice to use rolled-steel joist sections for both girders, but in older buildings

the main supporting units were of solid timber or flitched timber members. The bridging

joists are placed the short way of the room that is, parallel to the main girders. The

binders which give support to the bridging joist are themselves supported by the main

girders.


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12.2 METHOD OF CONSTRUCTION:

The floor is divided into three bays by two 375x175mm solid timber binders. These

support 150x50 mm bridging joists spaced at 375mm centres. The binders may be solid

timber beams, flitched beams, or rolled=steel joists put in position at 2.4 to 3.6m centres

across the shortest way of the room. They are supported at each end on 225 x 162x600

mm stone pads, with an allowance for a free passage of air round the ends of each binder.

Where the ceiling below needs an unbroken surface, ceiling joists are also needed. For

the outer bays, these joists may be supported at one end by fillets nailed firmly to the

sides of the binders, and at the other end by fillets securely fixed to the wall. The joists

for the middle bay are supported on fillets nailed to the binders.

The method of supporting the bridging joists and the ceiling joists are also shown. The

method of supporting the binder, the free passage of air round the beam, and a section

view of the stone pad are also shown here.

At the top are the plan and section of a floor 5.4m wide and 9m long, set out in three 3m

bays.

The details show a section through the floor with the bridging joist notched up to and

over the steel binders, and supported by steel angles. Also shown is a second method

where wood bearers are fixed to the steel binder by bolts, to receive the ends of the joist

which are notched up to the binder.

The bridging joists are lathed and plastered.

Cradling for the steel binder consists of firings which are halved at the joints to form

frames, fixed to the side of each bridging joists, and arranged around the binder to receive

the lath and plaster.

A side view of the steel binder and the cradling are also illustrated.


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FIGURE: 12.I: DOUBLE FLOOR FIGURE: 12.2: FRAMED FLOOR


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The plan and sectional view of a traditional framed floor is given. This example has

150x75 mm bridging joists, 275x 150mm binders, The sectional views of the flitched

girder and the bridging joists. Also shown is a sectional view of the binder and the

method of supporting the flitched girder.

The framed floor illustrated has a 375 x 125 mm steel girder, 275 x 150 mm solid wood

binders, 150 x 75mm bridging joists, and 100 x 50 mm ceiling joist.

The details show the method of supporting the binders and the fixing of the casing.

Control BCG006

Guidance Note Issued 01/01/2001 Rev B Page 1 of 2

The following table gives details of allowable spans and spacing between joists for the

most commontimber sizes used in floor construction. All the figures are based on normal

floor loadings in dwellings

where the floor construction is typically 18-25mm floor boards/sheets with up to 12.5mm

thick plasterboardand skim underneath. For any other situation these tables may not be

appropriate and you should refer to theApproved Document to Part A of the Building

Regulations or ask your Building Control Officer for advice.

When choosing a joist spacing you should also check that your floorboards (or sheets) are

themselves strong enough to span over the width chosen.

12.3 FLOOR JOISTS SUITABLE FOR DOMESTIC FLOOR LOADINGS

Size of joists Maximum clear span in metres for joist spacing of in mm400mm

450mm 600mm

97 x 50 1.98 1.87 1.54

122 x 50 2.60 2.50 2.19

147 x 50 3.13 3.01 2.69

170 x 50 3.61 3.47 3.08

195 x 50 4.13 3.97 3.50

220 x 50 4.64 4.47 3.91

147 x 75 3.56 3.43 3.13

170 x 75 4.15 3.96 3.61


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195 x 75 4.68 4.52 4.13

220 x 75 5.11 4.97 4.64

Timber sizes and construction details

Building Control BCG006

Guidance Note Issued 01/01/2001 Revision B Page 2 of 2

When constructing timber floors, you should also bear in mind the following

points:-

1/ Floors are used to give lateral restraint to walls, and where the joists run parallel to the

wall, straps need to be installed as shown in the details below. Normally these straps need

to be positioned every 2m along the wall, but up to 3m is acceptable where this is to

allow the formation of a stairwell or similar opening in the floor. The galvanized mild

steel straps must have a minimum cross sectional area of 30 x 5mm

2/ Around stairwells and similar openings it is often necessary to use trimmer beams to

support the ends of joists. These details are dealt with separately on guidance note

number 009.

3/ Where joists support a partition wall or under baths they usually need to be 'doubled

up' to

support the increased localised loading.

4/ On joist spans over 2.5m, strutting is required to prevent joists twisting when loaded.

For spans of between 2.5 and 4.5 m only one row of strutting is needed, at the mid span

position. For spans over 4.5 m two rows of strutting will be required, positioned at the

one third and two third span positions. Solid strutting should be at least 38 mm thick

timber extending to at least three

quarters the depth of the joist. For example, 200 x 50mm joists would need at least 150 x

38mm

timber used as strutting. Herringbone strutting should be at least 38 x 38mm timber but

can only

be used where the spacing between the joists is less than three times the depth of the joist.

Hence


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for a 150 x 50 joist, herring bone strutting can only be used up to a spacing of 450mm but

for a

200 x 50 joist, a spacing of up to 600mm would be satisfactory.


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WEEK THIRTEEN

13.0.0 NAILS, SCREWS AND BOLTS

The commonest fixing carried out by the carpenter and and joiner in building is nailing.

This type of connection may give a joint efficiency as low as 15 percent as a joint

efficiency of the order of 100 percent in the case of adhesives. This is due to the difficulty

of placing A sufficient number of units in the contact area of the member to be joined.

The main reasons for the low efficiency of the rigid bar type of connection, such as the

nailed or bolted joint, are:

The low shear strength of timber parallel to the grain.

The non- uniform distribution of bearing stress along the shank of the nail or bolt, e.t.c.

In steel work it is assumed that the bearing stress is uniformly distributed over an area

equal to the plate thickness multiplied by the bolt diameter.

Members joined by together using screws provide a more scientifically designed joint

fastening than that of nailing, but it is more costly. Screws may be position more

accurately, and have a much higher resistance to withdrawal, than nails, and serve as a

much better clamping device. In jointing, where nails or screws would not provide

sufficient strength bolts are employed. These serve mainly as a clamping device.

13.0.1 NAILS

Oval wire nails are used for carpentry and joinery work, and have less tendency to split

the timber because of their section when driven with the widest dimension in the same

direction as the grain of timber. Their sizes vary from 1-6 (25mm-150mm).

Circular nails are used for temporary work.


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Cut clasp nails are used for general purpose.

Floor brands are used for nailing floor boards and the length varies from 1.5to 3 (35-

75mm).

Spikes are wire nails used for securing large members, their length exceed 6 (150mm).

Joiners brands or springs are used by joiners and their length varies from 1to 2 (25-

50mm).

Panel pins are used generally for fine work, the fixing of mouldings, thin panel and

hardboard. Ring shank nails are used for heavy work (carpentry work).

Clout nails are used in fixing the ceiling board and laths to the joist.


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FIGURE: 13.1. DIFFERENT TYPES OF NAILS

Holding power of nails

A useful guide in obtaining the maximum holding power of nails in use is that the nail

should penetrate the timber into which it is driven by the distance equal to the thickness

of timber it is driven through.

13.0.2 SCREWS

Like nails, screws are made in variety of metals. The mild steel type is the most common;

copper, brass, stainless steel, and aluminium are others. They have also a number of

different finishes, such as galvanized, sheradized, nickel-plate, brassed, chromed, and

black japanned.

The sizes of wood screws vary between gauge NO. 0, having a shank diameter of

1.56mm, and gauge NO. 32 with a diameter of 12mm. And the length vary from 3.17mm

for the smaller gauges length to 152mm for the thicker screws.

Iron screws are the strongest and cheapest screws and used for ordinary purposes. But

they corrode easily especially in hard wood particularly oak.

Screws are available in various sizes from 1to 6 (25mm-150mm).

Flat or countersunk head screws

Round head screws used for fixing metal to wood.

Raised head screws also used for fixing metal to wood.

Coach screws with square or hexagonal head, used for heavy

construction job.

Holding power of screws


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Screws develop a greater resistance to withdrawal during the seasoning process of the

timber. This is the case with screws used in doors and windows which have been fixed in

position on the site for some time.

13.0.3 RAW BOLT

These are metal bolt-fixings designed for use in masonry. There are two types to meet

different method of fixing. The bolt and shell and the loose bolt type.

13.1.0 CONSTRUCTION OF WOODEN SILLS

13.1.1 WINDOW SILLS

A window frame is usually less thick than the wall in which it is built, unless the frame is

set flush with the outside face of the wall. Most of the area of a window is glass which

does absorb water and rain runs off it on to the external surface below. To prevent this

rain saturating the brickwork below the window, a sill is constructed. The sill may be of

wood, stone, tiles, brick, sheet metal, e.t.c. which will not absorb moisture. Internal

surfaceat

the bottom of a window will collect dust and may become damp from moisture which

condenses on the inside face of the glass and runs down.

It is usually to construct an internal sill of some materials which is hard and that can becleaned. A timber board, called a window board, is commonly used. Clay or concrete

tiles may also be used.

INTERNAL SILLS OF WOOD WINDOW BOARD: The usual way of finishing the

internal sill of windows is to fix a timber a timber window board. A softwood board is


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prepared with one edge rounded and it is fixed to grounds, plugs or fixing blocks in the

brickwork below the window.

It is not generally possible to drive nails through timber and in to brickwork. Most bricks

are too hard to be penetrated by nails, hence the use of grounds, plugs or blocks.

Timber grounds consist of lengths of small section sawn softwood. These grounds are

either nailed to wood plugs driven into brickwork joint or directly into mortar joints, to

provide a level surface to which the window board can be nailed.

Plugs are wedge shaped piece of timber driven into joints between bricks and to which

the window board is nailed.

Fixing blocks offcuts of lightweight aggregate concrete blocks which are built at

intervals into brickwork and into which nails can readily be driven.


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FIGURE: 13. 2. CONSTRUCTION OF WINDOW SILL


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WEEK FOURTEEN

14.0.0 CONSTRUCTION OF CENTRES FOR ARCHES

Centres are wood structures which are used as temporary supports for arches during

construction. Arches are constructed mainly of brick work masonry or concrete and they

may be flat, sequential or semi-circular in shape.

Centers consist of one or more rib which supports laggings. Laggings are cast to length

equal to the thickness of the wall. They are battens or plywood, nailed on the ribs to form

a platform for the walling.

Two types of lagging are common i.e. open lagging. The centers are supported or

vertical props.

Folding wedges are necessary to permit a slight vertical adjustment of levels. The wedge

also allows the center to be ease or lowered and then revolved (easing and striking).

Ribs form the profile of the arch and are made from sheet materials (plywood) or solid

section joined with metal plates or are built- up of two thicknesses of timber with their

joint s lapping. Ribs provide support and fixing for lagging.

Struts stabilise the framework by helping to redistribute some of the load placed on the

ribs.

Ties prevent built-up ribs from spreading and provide affixing for bearers.Bearers tie the base of the centre and provide a sole, under which the centre is wedge

and propped.

14.0.1 CONSTRUCTION

Start by drawing a full-size outline of half the centre. Remember to deduct the thickness

of the lagging (except for centres for segmental arches)

Segmental arch of 50mm rise may need only a turning piece but most will requires a

centre consisting of two curved ribs to span the width of the opening and to which

laggings are nailed.


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Semi-circular arch is supported on a centre consisting of two built-up ribs which are

prevented from spreading by the introduction of a tie. The laggings are 25x25 or

plywood. The centre is supported on 50x175 props.

FIGURE: 14.1. SEGMENTAL ARCH CENTRE


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FIGURE: 14.2. COSTRUCTION OF SEMICIRCULARARCH CENTRE

FIGURE: 14.3. COSTRUCTION OF TURNING

PIECE


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Centres for large arches: Regulations provide that for arches greater them 1.2m span,

braced or trussed centers should be used.

The centring systems described were mainly for supporting arches in buildings. Arches

which have a span more than 3m are required mainly in large structures as religious

buildings and arched bridges over rivers or roads.

Large centring systems are generally constructed by much the same methods as are used

for smaller units. Two way of forming large centers are:-

(a)Built-up from two, three or more laminations.

(b)Solid timber framed together with mortise and tenon joints which are secured with

metal fasteners (straps or bolts).

It is important that large span centring systems should be adequately supported, either by

stout timber shores or by a sufficient number of steel props


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FIGURE: 14.4. SEMICIRCULAR ARCH

CENTRE FOR DOMES

Domes constructed of concrete are usually hemispherical in shape. The centering for

those with span of 6m and over would be supported on a platform of steel scaffolding, or

some other steel props systems,

and it is general practice for such structures to be properly supported during

construction. Centre for small domes may be built in two ways i.e. they may either

consist of vertical ribs radiating from the centre of the dome with the curved surface

covered by horizontal boarding or it may be built on circular ribs. The circular ribs would

vary in sizes and would be placed horizontally and covered with vertical boarding.

14.1.0 CONSTRUCTION OF TIMBER SHORES

A shore is a member, generally of timber used temporarily to prop a wall which is either.

(a)Defective and likely to collapse

(b)Liable to collapse when alterations are made to adjacent property.

(c)Liable to collapse when being altered by the removal of its lower portion for

reconstruction.

Shores are the supports or props used in shoring.

14.1.1 METHOD OF CONSTRUCTION

Raking shores:- This is an inclined struts used to support a wall which shows signs of

failure such as cracks or bulge. The defects may be due to thrusts from one or more

upper floors, or from the roof or because of unequal settlement of its foundation. In its

simplest form the shore consist of struts, together with a suitable support at the foot and

fixing at the head. It consist of an inclined member supported at ground level on a piece

of wood called sole plate and secured at the top by wood needle inserted in the wall. The


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angle between the shore and the sole plate must be slightly less than 90oor 87

o. The wall

pieces provide a suitable abutment for the shore and fixing for the lower end of the strut

or brace. The wall piece is hold for the needle. The wall pieces are attach to the wall by

metal wall hooks wh

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Cec 103.- Workshop Technology 1

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