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SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case...

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SLANTING ROOFS www.universalconstruc t.ro
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Page 1: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

SLANTING ROOFS

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Page 2: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Appropriate isolation of roof must be connected with:

– The most important case is the protection of thermal insulation and roof’s construction from moisture.– The damp thermal insulation does not fulfil its function.– If the roof is damp, more heat escapes through it, sometimes as much as 40%.

1. Decrease of heat losses

2. Improvement of thermal stability of the building

3. Control over condensation of humidity in space dividing elements

4. Improvement of effectiveness of ventilation system operation

SLANTING ROOFS - GENERAL ISSUES

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Page 3: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Heat escape through the roof

- A roof is a place which is mostly exposed to outer atmospheric conditions (temperature, wind, rain)- About 23% of the heat goes away through a roof- Heat/warmth losses cause higher building maintenance costs.

Protection from heat losses - thermal insulation of the roof

- In case of flat or cold roofs, the insulated part is usually the ceiling- In case of slanting (steep) roofs with usable lof (attic)t the thermal insulation is placed between rafters

SLANTING ROOFS - GENERAL ISSUES

The thermal insulation property of the roof

does not result just from the significant thickness of the wool

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Page 4: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

What humidity is…

Absolute humidity is a ratio of the amount of water vapour (expressed in grams), found in a specific volume of air (x m3) and it is expressed in [g/m3]

Saturation humidity is the maximum amount of water vapour (humidity) which can be absorbed by the air in specific climatic conditions expressed also in [g/m3]

Relative humidity is the percentage ratio of the absolute humidity to the saturation humidity for a given air temperature

Examples of maximum amounts of water vapour that can be absorbed by 1m3 of air

temp. 30ºC - 30,3 gtemp. 20ºC - 17,3 gtemp. 10ºC - 9,4 gtemp. 0ºC - 4,8 gtemp. -10ºC - 2,4 gtemp. -20ºC - 1,1 g

SLANTING ROOFS - GENERAL ISSUES

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Page 5: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Sources of water vapour

1. Weather conditions

2. Plants - pot plant produces 15 – 50 g/h of water vapour

3. Human activity - human - natural physiological activities (breathing or perspiring) - sleeping person 40 – 50 g/h - working person 90 – 200 g/h - cooking 200 – 250 g/h - taking a bath 1000 g/h - taking a shower 1700 g/h

4. Construction work performed - new walls - new plaster - new floors

SLANTING ROOFS - GENERAL ISSUES

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Page 6: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

The dew-point temperature

SLANTING ROOFS - GENERAL ISSUES

The air is capable of absorbing a specific amount of humidity.This capability increases while the temperature rises and decreases while the temperature drops down. If we cool the non-saturated air then it will get saturated at a certain temperature, which we call a dew-point = saturation point temperature.If we cool the air down below this temperature forces the vapour to drop out from the air.

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Page 7: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Heat and humidity interactions

Majority of external climatic conditions change - throughout the day (day-night)

Internal conditions change - throughout the year (winter – summer)- external

SLANTING ROOFS - GENERAL ISSUES

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Page 8: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

The most important problems to solve are the following:

1. Protection of thermal insulation against the water vapour from living quarters as well as against the atmospheric moisture and rain;

2. Right selection of appropriate materials creating an efficiently functioning system;

3. Correct ventilation of loft rooms and thermally insulated roof slopes so it is possible to remove the moisture from them.

4. Proper execution of assembly work.

PROTECTION AGAINST HUMIDITY

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Page 9: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

The layers protecting the roof A properly constructed roof with a usable loft may consist of a number of layers, each of which fulfils a specific function. The purpose of all this is an efficient protection of the building against humidity and excessive loss of heat

1. Proper roofing (protects against precipitations)2. Initial roofing layer (protects against humidity from outside)3. Thermal insulation (this is thermal and acoustic insulator)4. Vapour barrier film (blocks the access of humidity from inside)5. Gypsum boards (they constitute internal roof sheathing)

PROTECTION AGAINST HUMIDITY

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Page 10: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

In modern roof structures, while solving problems relating to penetration of the water vapour, was developed the system in which:

- on the external side there is mounted a vapour-permeable foil;

- on the internal side there is a vapour barrier foil used.

The simultaneous installation of both foils: vapour permeable (1) and vapour insulation (3) creates an excellent system, in which the access of the vapour is highly limited, and the humidity affecting the thermal insulation (2) and roof’s construction has the possibility to get out and it does not condense in time.

ROOFING FOILS

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Page 11: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

When selecting a primary coverage foil one has to take into consideration:

1.The method of the roof’s ventilation

• Ventilated roofing

• Tight roofing

2. The attic usage form (cold, usable)

3. The type of proper roofing

• roofing made of bigger, tightly joined elements - the best material to be used as an initial roofing layer is the foil of nearly zero vapour-permeability with vapour-barrier properties.

•if the roof is to be covered with small elements installed with overlaps– both types: vapour-permeable and vapour-barrier can be used.

ROOFING FOILS

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Page 12: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Ventilated roofing, Cold loft.

Cold loft. Ventilated roofing, - ventilation gap under the main roofing- initial roofing layer - ventilation gap under the initial roofing layer- thermal insulation on the ceiling- small ventilation holes in gable walls

Cold loft. Ventilated roofing, - ventilation gap under the main roofing- initial roofing layer- thermal insulation on the ceiling - ventilation holes in gable walls

both types of foil, poorly and highly vapour-permeable one

Highly vapour-permeable foil

ROOFING FOILS

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Page 13: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Ventilated roofing. Usable loft.

Usable loft. Ventilated roofing. - ventilation gap under the main roofing- initial roofing layer - ventilation gap under the initial roofing layer - thermal insulation between rafters

Usable loft. Ventilated roofing. - ventilation gap under the main roofing,- initial roofing layer- thermal insulation between rafters

Poorly vapour-permeable foil Highly vapour-permeable foil

ROOFING FOILS

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Page 14: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Tight roofing; Cold and usable lofts.

Cold loft. Tight roofing. - initial roofing layer- ventilation gap under the initial roofing layer- thermal insulation on the ceiling- ventilation holes in gable walls

Usable loft. Tight roofing.- initial roofing layer- ventilation gap under the initial roofing layer- thermal insulation between rafters- small ventilation holes in gable walls

vapour barrier foil vapour barrier foil

ROOFING FOILS

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Page 15: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Vapour-permeable foils

Basic function of Vapour-permeable foils is to protect the thermal insulation and roof structure against the following:

- Water during assembly work;

- Water blasted under the roofing in the form of snow or rain;

- Condensate forming under the roofing;

- Water in case of temporary damage of the roofing

ROOFING FOILS

The advantages of vapour permeable foils Strotex

- Resistance to low and high temperatures;

- It does not propagate fire;

- Lightness (one metre of foil weights 60-170 grams);

- Good strength.

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Page 16: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Water vapour permeabilityit is the capability of the material to allow water vapour to go through, which is calculated in grams being let go through within 24h of he surface of 1m2 in the appropriate climate conditions

The amount of the water vapour let through the foil depends on temperature, relative humidity and differential pressure.

•temperature of 23OC and humidity of 50% 1.700 g/m2/24h vapour-permeability

•temperature of 38OC and humidity of 85% 3.000 g/m2/24h vapour-permeability

In order to avoid the above mentioned problems, it is more convenient to determine the vapour-permeability using the Sd

coefficient, which:

• is independent from temperature and humidity

• corresponds to the thickness of an air layer of the same diffusional resistance as the one of the construction material

ROOFING FOILS

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Page 17: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Division of vapour-permeable foils depending on their diffusional properties:

1. Low vapour permeability 10-100 g/m2/24h; Sd = 0,3 - 10mreinforced or having an anti-condensation layer

they require a ventilation gap over the thermal insulationSTROTEX SL PPSTROTEX 110STROTEX 140

2. High vapour-permeability 800 - 4000 g/m2/24h; Sd = 0,012-0,1m made of materials of high permeability of the water

vapourthey may touch directly the thermal insulationSTROTEX 1300 BasicSTROTEX 1300 VSTROTEX 1300 Supreme

ROOFING FOILS

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Page 18: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Technical parameters of vapour-permeable STROTEX FAMILY roofing foils

ROOFING FOILS

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Page 19: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Vapour-barrier foils

- protect the structure and thermal insulation of space dividing elements against the inflow of the water vapour from usable rooms, from building interior

- prevent the heat losses caused by wind blowing

They are always laid on the warm side of the dividing element, on rafters at the loft side.

The vapour insulation tightness is a very important condition of its proper functioning. When it is laid down in a bad way, with holes, it causes more harm than a lack of it.

One should take care of the tightness of each stripes of the vapour insulation and its connection points with the roof construction elements as well as with walls, especially in corners of the buildings)

ROOFING FOILS

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Page 20: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

The division of vapour-insulation foils concerning their construction

Types of vapour-barrier foils:

1. Non-reinforced – single-layer polyethylene foils of the thickness of 0.15 – 0.5mm

- EKOFOL PI- BUDFOL PI- BUDFOL 3W

2. Reinforced – strengthened with fabric or mesh

- STROTEX SL PI- STROTEX 110 PI

3. With an aluminium or metalized layer – multi-layer one with a thin metal layer- STROTEX AL

4. With viscose or polypropylene cloth – multi-layer one with an absorbing layer- STROTEX AC 140

- BUDFOL ANTYDROP

ROOFING FOILS

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Page 21: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Vapour-barrier foils according to their diffusional properties:Vapour-barrier foils 0–0.1 g/m2/24h; Sd = 60-100 m

– Made of vapour-impermeable materials

– This kind of foil usually contains an aluminium layer

– This kind of foil is also called a reflexive one because it additionally reflect the heat radiation.

Vapour delayers 0.2–3.0 g/m2/24h; Sd = 15-50 m

–A kind of foil which is slightly permeable for the water vapour through the diffusion process and it only delays penetration of the water vapour without being an ultimate barrier.Vapour regulators 4.0–6.0 g/m2/24h

– Materials characterised by better vapour-permeability.

– One of the regulator layer is a damp absorbing cloth, which supports the anti-condensation action

– They may be located between thermal insulation layers.

– They require the usage of highly vapour permeable foil on the other side of the barrrier

ROOFING FOILS

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Page 22: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Wind-barrier foils WIGOFOL

ROOFING FOILS

1. main roofing (asphalt roofing or bitumen tile)2. board roofing3. Ventilation space4. wind-barrier foil (WIGOFOL)5. therm insulation

Wind-barrierprotects the heat from escape on the base of the air movements originating in the non-tight places between the thermal and the construction and from the atmospheric humidity inflow into the space of protected barrier. The wind-barrier makes it impossible to blow out insulation elements and it prevents the dust from settling on it.

Wind-barriers are used mainly in the structures of stud walls on the external side.

They can be also installed on ventilated roofs, where the role of the initial roofing layer is played by the sheathing made of boards and roof paper or which are covered with bituminous tiles. In this type of roofs it also fulfils the function of material creating distance between the thermal insulation and the covering.

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Page 23: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

How to choose roofing foil

Installation of both types of foil (vapour-permeable and vapour-barrier) at the same time, creates a perfect system in which the access of the water vapour is considerably limited.

Materials should be selected in such a way that:

-the diffusional resistance of individual layers decreases from inside towards outside the roof;

-the diffusional resistance of the vapour-barrier foil should be the bigger, the bigger is the diffusional resistance of the initial roofing layer.

initial roofing foil Sd < 0.3 m the vapour-barrier foil Sd >= 2 m.

initial roofing foil Sd > 0.3 m (poorly vapour-permeable foils) more efficient vapour-barrier foils should be used.

ROOFING FOILS

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Page 24: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Ventilation of usable attics

The method of ventilation depends on the type of the applied initial roofing layer. Ventilation of such roofs may be performed by means of one or two ventilation gaps

1. Two gaps are required if the boarding with roofing paper or poorly vapour-permeable foil were used as the initial roofing layer. The lower gap dries the insulation and the roof structure

2. Highly vapour-permeable foils enable to eliminate the lower ventilation gap and the whole water vapour is removed through the upper gap created by the battens. In this situation the efficiency of the upper space is particularly important

ROOF SLOPES’ VENTILATION

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Page 25: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Ventilation of usable attics

A roof with poorly vapourpermeable foil. 1. Proper roofi ng, 2. Upper ventilation gap, 3. Poorly vapour-permeable foil (STROTEX), 4. lower ventilation gap, 5. Thermal insulation.

ROOF SLOPES’ VENTILATION

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Page 26: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Appropriate ventilation of roof slopes provides the following benefits:

- Removes heat plugs;- Quicker drying of slopes, e.g. after precipitations;- Draining the water vapour outside the building; - Decrease of temperature differences on both sides of the roofing

In case of steep roofs with usable loft:- the ventilating space is limited to the gap

In case of cold lofts the thermally insulated part is the ceiling:- the roof itself does not have to be insulate;- the thermal insulation is installed on the ceiling

ROOF SLOPES’ VENTILATION

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Page 27: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Foils of a high vapour permeability can be applied directly on the thermal insulation

Ventilation of usable attics

A roof with Highly vapour-permeable foil. 1. Proper roofing, 2. Ventilation gap. 3. Highly vapour-permeable foil (STROTEX), 4. Thermal insulation.

ROOF SLOPES’ VENTILATION

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Page 28: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Ventilation of usable attics

Roof with special highly vapour-permeable foil STROTEX - dedicated to completely boarded roofs. 1. Proper roofing, 2. Ventilation gap, 3. special highly vapour-permeable foil STROTEX, 4. wooden board sheathing, 5. Thermal insulation

Some types of highly vapour-permeable foils can be installed directly on the roof boarding, those are foils with im proved resistance to tear.

ROOF SLOPES’ VENTILATION

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Page 29: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Ventilation gap size

- The size of a gap is determined by its cross-sectional area size of the ventilation section = 0.2% of the related roof area, but not less than 200 cm2/1m of the roof width

- The water vapour moves in the most efficient way along with the air- To make the ventilation efficient, an inlet and outlet of atmospheric air have to be made. The ventilation gap has to be open from the bottom, under the inlet and from the top, by the roof ridge (outlet).

- Ventilation sections of the ventilation gap inlet openings on the roof ridge or on the roof corner must constitute 0.05% of the roof area (one slope).

*it is necessary to take into consideration the loss of the gap section area on the width of battens and counter-battens, which constitutes ca. 16% of the section area.

ROOF SLOPES’ VENTILATION

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Page 30: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Ventilation gap size

Examples of gap sizes the gap is calculated for one side of the slope

ROOF SLOPES’ VENTILATION

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Page 31: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

The most common mistakes in usage, exploitation and installation of roofing foils

1. Very often elements of the thermal insulation protection are not properly selected and laid down in proper places- Improper application brings big losses, and the whole system does not function well.

2. Properly installed foils restrict the uncontrolled flow of the water vapour through the roof and in this manner they prevent the structure and roof thermal insulation from getting damp

3. Remember that the use of STROTEX, BUDFOL or EKOFOL foil must be compliant with technical documentation of the building, the building law and the rules of roofwork.

MISTAKES IN APPLICATION

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Page 32: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

The incorrect placement/ installation of roofing foils

1. Installation of the highly vapour-permeable initial roofing foil in tight plating results in the lack of atmospheric air flow.2. The application of wind-insulation in a place of initial roofing layer

3. Installation of the poorly vapour-permeable foil directly on the boarding with thermal insulation pressed underneath will result in quick

deterioration of that boarding

MISTAKES IN APPLICATION

4. Improper sequence of works Installing a vapour insulation foil when the insulation is wet or just after wet finishing works closes inside the vapour and diminishes its thermal insulation properties.

5.Too long exposure time to the Sun activity without installing the main roofing on it may result in structural changes caused by UV radiation.

6. Lack of contr-patches on roofs covered with metal sheets stops the water on connections of rafters and speeds up foils degradation

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Page 33: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

8. Lack of or improper permeability of the ventilation slot Obstruction of a gap restricting the air flow will have similar results as the lack of the gap. These are some possible reasons of such obstructions:

- Lack of appropriate inlet and outlet openings - Cutting of the ventilation connection (in case of protruding elements) - Lack of separating materials or ventilation inserts - Installation of the thermal insulation thicker than the rafter height - Corrugation or slipping of the thermal insulation, especially in the area around the eaves - Thermal insulation is pressed to the foil installed loosely under the metal plate - The foil is pushed out by the insulation - Formation of a snow-ice block in the eaves

MISTAKES IN APPLICATION

9. Incorrect instalation of foils in valleys leads to lack of tightness and leakage under the foil installed on the other slope.

10. Mechanical damage of the foil

7. Lack of ventilation slot over thermal insulation causes serious dampfening of the insulation in roofs with poor-permeable foils or with roof paper.

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Page 34: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

MISTAKES IN APPLICATION

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Page 35: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

The manual instruction of roofing foils’ installation

- The whole system will work correctly only if all the work is done properly and with due care.

- All the rules related to installation and joining of foil pieces need to be obeyed.- The use of the Strotex foil must be compliant with the technical documentation of the building, the binding legal regulations and the rules of the roofwork.- Differences in the method of installation of highly and poorly vapour-permeable STROTEX roofing foils result from their different properties.

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 36: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

General rules

1. The roofing foil does not function as the main roofing layer, that is why it is necessary to install the proper roofing within the indicated period, otherwise the foil may be damaged because of excessively long exposition to UV radiation.2. During extreme weather (long-lasting precipitations, slanting rain with blasts of wind) water may locally penetrate in overlaps; in case of counter-battens, there may occur the physical phenomenon of capillary penetration of the dampness.3. Superficial damage of all types of foil should be repaired with cut off pieces of the original material; connections should be insulated with the assembly belt.

4. Possible large damage of the main roofing (tiles, metal plate) should be repaired

as soon as possible.5. The foil should not be laid on recently impregnated elements of the roof structure.

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 37: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Direction of installation

• The foil may be laid in parallel or perpendicular to the eaves, • Always the side with inscriptions facing upwards. • The direction of installation of the foil on rafters is of no importance for their functioning, but it is more convenient to lay them in parallel to the eaves. • Installing the foil along rafters is justified in some cases only, namely if the main roofing consists of large sheets laid perpendicularly to the eaves or during renovation works, when it is best to carry out the work zone by zone. • Installation of the foil should always be started from the bottom of the roof. • The lower edge of the foil must overlap with the eaves flashing.

1. Flashing, 2 foil

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 38: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Tension

Possible methods of permeable foils tensile

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 39: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Overlapping

- Subsequent stripes of the foil should be laid in such a way that they overlap, - The size of that overlap depends on the roof inclination degree. - The correct dimension should be 10-15 cm (the width of the indicates an overprint). - With the roof inclination below 22°, the overlap should have at least 20 cm. - The stripes can be attached to each other with special assembly band. - In case of complete boarding, the upper stripe must cover nails in the lower layer.

1. First strip of foil, 2. Second strip of foil, fitted with adequate overlap, 3. printed width overprinted on the foil

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 40: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Fixing

- All the vapour-permeable foils are nailed directly to the rafters (boarding) with staples by means of an electric stapler.- At the end, the foils are pressed to the rafters (boarding) by counter-battens nailed immediately from above. - Counter-battens have to be fixed in order to eliminate the dampness transfer in the area of nails.

- It is recommended to tighten the spacer between the patch and the rafter, and also the place sof the foil’s nail punctures- Installation without counter-battens may only be performed at one’s own responsibility.- Foils should be installed at the same time when the battens are nailed to the main roofing. 1. foil, 2. Staples, 3. counter-laths

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 41: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Joining

If it is necessary to make longitudinal connections, layers have to lay on rafters and be joined and insulated with the assembly band

In case of horizontal installation, vertical connections of foils should be usually avoided

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 42: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Ventilation gap

- The upper ventilation slot is being created in a natural way by the patches and contr-patches if the gap is to be effective, it should have unobstructed inlet in the roof eaves and outlet in the roof ridge- If the existing openings in the roof ridge and eaves are not efficient enough, it is necessary to install additional ventilation tiles.

- Foils with good diffusional properties do not need a ventilation gap over the thermal insulation.

- Low permeable foils require additional ventilation slot over the thermal insulation.

-The ventilation slot over the thermal insulation is also required when as the primary covering roof paper with woods has been used.

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 43: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Ventilation slot-permeability (poore vapour-permeable foils)

1. To make a gap located over the thermal insulation function properly, it has to be made using separating materials, maintaining its appropriate size at the whole length of it (eg. rope or fabric).2. The foil needs to be fixed around systems extending above the roof in such a way that the ventilation gap is not blocked3. In complicated roof constructions, to ensure the ventillating air flow in doubtful places, ventilation fillers should be applied, connecting the space over and under the foil.

1. ventilation insert, 2. upper ventilation gap, 3. foil, 4. lower ventilation gap

1. ventilation insert, 2. upper ventilation gap, 3. foil, 4. lower ventilation gap

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 44: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Eaves

The eaves is a place where the foil is installed first.

Foil should be glued to the metal sweet strip in the eave by means of two sideł gluing tape.(This protects against the rustle and excessive stretching of the foil during strong winds and guarantees free air flow)

Directly to the gutter

1- highly vapour-permeable foil; 2- fleshing; 3- gutter

Under the gutter

1- highly vapour-permeable foil; 2- fleshing; 3- gutter

In both cases the sticking out foil should be protected from the despersed Sun rays.

There are two ways of the foil’s output, so the drops to go out:

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 45: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Roof ridge

Installation of the foil in the roof ridge depends on:1) the type of foil used 2) on the method of thermal insulation installation.

Types of roof ridges: 1) Open, used when poorly vapour-permeable foil is applied; 2) Closed, used when highly vapour-permeable foil is applied.

Open roof ridge with ventilation gap protection

Open roof ridge Closed roof ridge

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 46: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

The chimney

- The foil around the chimney should be properly cut off and fix to the chimney by the two side tape- All parts of the foil sticking out to the chimney should be about 10-15 cm long.- There should be a gutter made from foil over the chimney, to protect it from getting damp- The foil gutter drains the potential water out of the neighbouring rafters.

1. parts of foil turned up on the chimney, 2. small gutter

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 47: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Roof windows

- Openings for roof windows are to be cut once the foil is already installed.

- The foil has to be cut in such a way that it is possible to turn it up on the window frame.

- The foil is to be fixed with two-sided adhesive tape or a sealing flange provided by the window manufacturer.

- A small gutter carrying the water away should be made over the windows, just like over other elements.

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 48: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Elements coming through the roof Small elements (ventilation chimneys, aerials, etc.) on the building going through the roof have to be properly sealed and cuttings in the foil should be as matching the opening as possible and be small.

2. Highly vapour-permeable foils – a star-shaped cut should be done and next, after the element is taken through the cut opening in the foil, turn foil elements upwards around the element and tightly seal with a tape.

It is recommended to make a small gutter from an additional stripe of foil above that element to carry away the water that could possibly accumulate there.

1. Poorly vapour-permeable foils - A trapezoid-shaped opening should be cut in the foil with the longer trapezoid base facing upwards. The cut has to be made in such a way that it is possible to use the cut foil to make a covering gutter engaged on the nearest upper batten.

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 49: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Small gutter

The gutters protect against the flowing condensate or leaks. They are usually made of:a) additional pieces of foil which are placed under the nearest overlap; b) “U”-shaped cut made over the covered element. The base of the letter “U”

should be longer than the width of the protected opening.

Possible method of water carring through the small gutter

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 50: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Gable wall

- If the roof does not protrude over the gable wall of the house, the foil has to be installed on the wall, too. - In case of walls next to the roof slope, the foil has to be turned up by ca. 5 cm above the roofing surface.

When the roof does not porteude over the gable wall

1. foil, 2. gable wall

When the wall is next to the roof slope

1. foil, 2. neighbouring wall, 3. part of foil turned up on the wall

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 51: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Ridge

Sequence of foil layer installation on the roof ridge.

1. right stripe, 2. left stripe installed with overlapping to the right side,

3. additional stripe of foil

VAPOUR-PERMEABLE FOIL INSTALLATION

- In order to cover the roof ridge, stripes of foil from the neighbouring slopes have to be laid overlapping by at least 10-15 cm.

- For better protection, it is also possible to lay on the ridge an additional stripe of foil tightly connected with the foil installed on the slopes.

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Page 52: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Valey

Sequence of foil layer installation in the valley.

1. additional stripe of foil,

2. right stripe,

3. left stripe installed with overlapping to the right side

VAPOUR-PERMEABLE FOIL INSTALLATION

The valley is a place particularly vulnerable to leaks. It should be covered with a double layer of foil. It is recommended to:

- install an additional stripe of foil underneath the valley rafter; - lay individual stripes of foil from each slope to overlap the neighbouring slope by at least 25cm. - attached overlaps with two-sided self-adhesive tape.

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Page 53: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Loft renovation – installation of the foil on an existing roofIn case of works that will not involve disassembly of the roofing, the foil should be installed between rafters using soffit panels or spacers forming a ventilation gap in such a way that the thermal insulation material laid on the loft side does not press the foil to the roofing. Because of the direct contact of the insulation with the foil, only highly vapour-permeable foils can be used. In order to ensure appropriate air circulation, suitable intake and exhaust ventilation openings should be made in the eaves and the roof ridge. Openings in the eaves will also be used to drain the condensate.

Method of installation of highly vapour-permeable foil during loft renovation

a. using soffit panels b. using spacers

VAPOUR-PERMEABLE FOIL INSTALLATION

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Page 54: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

Principles of vapour-barrier foil installation 1. It can be used in all types of ventilated and non-ventilated roofs.

2. The foil can be installed in perpendicular or parallel to the rafter, always on the warm side of the thermal insulation, starting the installation from the top.3. Subsequent stripes of foil are laid overlapping, and the width of the overlap depends on the direction in which it is installed.

4. It is important to maintain correct overlap dimension: - 15 cm if its is laid in parallel to the rafter - 20 cm if it is laid perpendicularly to the rafter.

1. thermal insulation,

2. vapour-barrier foil,

3. gypsum boards

VAPOUR-BARRIER FOIL INSTALLATION

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Page 55: SLANTING ROOFS . Appropriate isolation of roof must be connected with: – The most important case is the protection of thermal.

5. In case of longitudinal installation, connections of neighbouring stripes have to lay on rafters.6. The foil is connected with rafters by means of staples, and overlapping stripes are tightly connected by means of the two-sided adhesive tape.

7. Two-sided self-adhesive sealing tapes should be used on connections with elements reaching outside the roof, and it is recommended to use additionally pressing slats next to vertical elements, such as walls or chimneys.

8. The foil has to be laid without any damage or folds and all connections should be properly sealed.

All the loft rooms, independently from the type of the vapour-insulation used, should have efficient ventilation enabling the air exchange.

1. gypsum boards, 2. vapour-barrier foil, 3. self-adhesive sealing tape, 4. pressing slat

VAPOUR-BARRIER FOIL INSTALLATION

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