Contribute to Setting Out
Tutor Copy
SETTING OUT
For measuring when setting out, builders may use a 30
metre setting out tape.
The tape measure can be either made of fabric or metal.
With constant use and pulling the tape tight a fabric tape
could tend to stretch which could give an incorrect reading.
Wipe all tapes clean after use and to maintain a metal tape,
lightly lubricate it with oil
SETTING OUT A 90 DEGREE ANGLE (SQUARE)
For ease of construction and to keep building costs to a
minimum the majority of buildings are made up of a collection of
squares and rectangles. Squares and rectangles all have
angles/corners at 90 degrees.
There are several ways to set out or check a right angle on site.
BUILDERS SQUARE
Never presume that the square is accurate. It may have been
made faulty or damaged through use or neglect.
To check a square for accuracy lay it on a flat surface and draw
round the 90 degree end. Totally reverse the square and place it on
the lines you have just drawn. If the square follows the lines, it is
accurate, if it shows different it is faulty.
3:4:5 METHOD
This method is also known as Pythagoras. A triangle having
sides measuring 3m, 4m & 5m, creates a perfect 90 degree
angle, at the corner. By using this method builders are able to
set out a square corner using just a tape measure.
A B
C
3m
5m
90 degrees
4m
SETTING OUT OTHER ANGLES
90 degree angles, and other angles, can also be set out using
optical equipment, such as a Site Square or a Theodolite.
Nowadays it is quite commonplace to use equipment
incorporating a laser beam and setting out buildings can now
be achieved with the use of satellite navigation.
SET OUT A 45° / 135° ANGLE(FROM POINT A)
EQUIPMENT REQUIRED =
STRAIGHT-EDGE / BUILDERS SQUARECHALK OR PENCIL / TAPE MEASURE. 1.EXTEND WALL LINE XA TO B. 2.MEASURE ANY DISTANCE FROM A (600mm) TO FIND POINT B. 3.DRAW LINE BC AT 90° TO LINE XB (USE BUILDERS SQUARE OR 3:4:5 METHOD) 4.MEASURE FROM B TO C (600mm) – same distance as in Step 2. 5.JOIN POINTS A TO C. 6.LINE AC CREATES A 45° ANGLE WITH LINE BX & ALSO CREATES A 135° AT THE ANGLE AT CAX
SETTING OUT OTHER ANGLES
C
135° 45°
AX
B
IN A SQUARE ALL THE ANGLES ARE 90°.BY DRAWING A LINE FROM CORNER TO CORNER THE ANGLES HAVE BEEN HALVED.
SET OUT A 60° / 120° ANGLE (FROM POINT A)
EQUIPMENT REQUIRED =STRAIGHT-EDGE / CHALK OR PENCIL / TAPE MEASURE / TRAMMEL SET COMPASS OR LINE
STEP 1
1. EXTEND LINE XA.
USING A COMPASS SET AT ANY DISTANCE ((600mm) OR A PIECE OF LINE AND CHALK SCRIBE AN ARC TO CREATE POINT B.
STEP 1
1. EXTEND LINE XA.
USING A COMPASS SET AT ANY DISTANCE ((600mm) OR A PIECE OF LINE AND CHALK SCRIBE AN ARC TO CREATE POINT B.
X A
C
B
STEP 2 PLACE COMPASS POINT ON B, WITH COMPASS SET TO SAME DISTANCE, AND SCRIBE AN ARC, INTERSECTING THE PREVIOUS ARC TO CREATE POINT C
X BA
STEP 3
DRAW A LINE FROM A TO C. THIS LINE CREATES A 60° & A 120° ANGLE TO THE BASE LINE BY JOINING B TO C CREATES AN EQUILATERAL TRIANGLE. THIS SHAPE HAS ALL 3 ANGLES EQUAL TO 60°
120° 60°
B A X
C
THE BUILDING LINEThis is an ‘imaginary’ line, determined by the Local Authority Highways Department. This line is usually a measurement taken back from a point on the highway – maybe the centre of the nearest road, the kerb line of the pavement, or a manhole in the roadway. Its’ function is for any possible future road widening; therefore to make sure that any new construction will be far enough back from the highway. Any infringement of this measurement could result in fines or legal proceedings to remove any construction in front of this set measurement. Contacting the Highways Dept. will position this line. Consider that if the construction faces more than one roadway, there could be more than one Building Line measurement required.
ROADWAY
KERB LINE
MEASURED BACK FROM KERB LINE
BUILDING LINE
No permanent part of the construction may overstep the Building Line. You may build up to the Building Line, behind it, but NOT INFRONT of it.
THE BUILDING LINE
SETTING OUT A RECTANGULAR BUILDING
Setting out is required to locate the position of a building on the
ground. The setting out determines the positions of the walls,
which in turn determine where the ground is to be excavated
and the concrete poured, to create the foundation trenches.
EQUIPMENT REQUIRED:-
DRAWING / 30M TAPE / 3M TAPE/ STEEL SETTING
OUT PINS / LUMP HAMMER
STEP 1 AFTER DETERMINING THE POSITION OF THE BUILDING LINE, SET OUT USING STEEL PINS AND BUILDING LINE TO POSITION THE FRONTAGE LINE (AB) OF THE NEW BUILDING STEP 2 DETERMINE ONE OF THE FRONT CORNERS (A) AND SET LINE (AC), SQUARE TO THE FRONTAGE LINE.
FRONTAGE LINE
C
A
B
D
STEP 3 MEASURE THE LENGTH OF THE BUILDING ( A – B) AND ESTABLISH POINT B. STEP 4 ERECT LINE BD, MAKING SURE THE ANGLE AT B IS 90 DEGREES.
C
A
CHECKING THE DIAGONALS
STEP 5 MEASURE THE WIDTH OF THE BUILDING, A-C & B-D. POSITION A LINE FROM THESE 2 POINTS TO COMPLETE THE RECTANGLE.
D C
B A
STEP 6 TAKE A MEASUREMENT FROM CORNER TO CORNER (A - D & B - C). WHATEVER A – D MEASURES THEN B – C MUST MEASURE THE SAME. IF BOTH DIMENSIONS ARE THE SAME THAT MEANS THAT EACH CORNER IS PERFECTLY SQUARE. IF DIMENSIONS DIFFER THEN THE SETTING OUT PROCESS MUST BE RE-CHECKED FOR FAULTS. STEP 7 AS A FINAL CHECK, RE-CHECK ALL THE DIMENSIONS FOR ACCURACY
D C
B A
The next process is to erect CORNER PROFILES, set back from each corner.
As shown above, timber pegs are driven into the ground and a timber profile board nailed across.
SETTING OUT LINE
PROFILE BOARD SIZE APPROX. 75mm x 30mm
TIMBER PEGS APPROX. 50mm x 50mm
STEEL SETTING OUT PIN
SETTING OUT LINE
CORNER PROFILES
Because the steel setting out pins will need to be removed for excavation
of the building, each timber corner profile, because it is set back, can
remain in position whilst the building foundations are removed/excavated.
The setting out lines are extended from the steel setting out pins and the
positions of each line marked onto the profile board. When the bricklayer
begins to set out the external walls he/she can attach the lines onto the
relevant marks, without the need for having to set out the building again.
THE POSITIONING OF SETTING OUT PROFILES FOR A TYPICAL BUILDING
The setting out profiles are set back from the building so that they will not get hit by machinery working on the excavation. If excavation was to be carried out by hand the profiles could be positioned closer to the works.
When the foundation concrete has set the original setting out lines are fastened to the setting out profiles, once again. The bricklayer now needs to transfer the lines positions onto the concrete foundation. This is achieved by carefully plumbing down where the lines travel and marking this onto the concrete. These marks represent the positions of the walls from above ground to below ground.
LINES PLUMBED DOWN AND POSITIONS MARKED ON TO THIN SMEAR OF MORTAR. BRICKWORK CAN THEN BE SET OUT, BELOW GROUND LEVEL, IN THE CORRECT POSITION.
LEVELLINGInitially all four corners of a building will have to be built up to the same level.
This is usually firstly achieved for the horizontal damp proof level, which is generally 150 mm, above
finished ground level.
All buildings have a levelling DATUM point. This datum would be shown on the working drawing and it
is quite often the ground floor finished floor level, shown as F.F.L. More often than not this level is
usually the same as the D.P.C. level.
To find the F.F.L. / D.P.C. level of a proposed new building it may be necessary to transfer a level from
a datum elsewhere, possibly a long way away. This would be one of the first tasks to be done on a
construction site and a surveyor would set up the SITE DATUM or TEMPORARY BENCH MARK.
site datum or temporary bench mark is a point
where all levels, either above ground, or below
ground are initially taken from. can be a length
of steel angle iron set firmly into the ground and
surrounded by concrete. to protect the datum
from damage, by plant, it would be positioned
away from activities and surrounded by a fence.
Symbol relating to a datum point
For greater distances more accurate devices are required, such as :-
DUMPY LEVELQUICK SET LEVELTILTING LEVEL (AUTOMATIC) THEODOLITE LASER LEVEL