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SLANTING ROOFS
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SLANTING ROOFS - GENERAL ISSUES
Appropriate isolation of roof must be connected
with
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

• The most important case is the protection of
  thermal insulation and roofs 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.

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SLANTING ROOFS - GENERAL ISSUES

• 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

The thermal insulation property of the roof
does not result just from the significant
thickness of the wool
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SLANTING ROOFS - GENERAL ISSUES
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 g temp. 20ºC - 17,3
g temp. 10ºC - 9,4 g temp. 0ºC - 4,8
g temp. -10ºC - 2,4 g temp. -20ºC - 1,1 g
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SLANTING ROOFS - GENERAL ISSUES
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
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SLANTING ROOFS - GENERAL ISSUES
The dew-point temperature
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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SLANTING ROOFS - GENERAL ISSUES
Heat and humidity interactions
Majority of external climatic conditions change -
throughout the day (day-night) Internal
conditions change - throughout the year (winter
summer)- external
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PROTECTION AGAINST HUMIDITY

• The most important problems to solve are the
  following
• Protection of thermal insulation against the
  water vapour from living quarters as well as
  against the atmospheric moisture and rain
• Right selection of appropriate materials creating
  an efficiently functioning system
• Correct ventilation of loft rooms and thermally
  insulated roof slopes so it is possible to remove
  the moisture from them.
• Proper execution of assembly work.

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PROTECTION AGAINST HUMIDITY
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)
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ROOFING FOILS
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 roofs
construction has the possibility to get out and
it does not condense in time.
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ROOFING FOILS

• When selecting a primary coverage foil one has to
  take into consideration
• 1.The method of the roofs 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.

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ROOFING FOILS
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
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ROOFING FOILS
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
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ROOFING FOILS
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
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ROOFING FOILS
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

• 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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ROOFING FOILS
Water vapour permeability
it 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

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ROOFING FOILS
Division of vapour-permeable foils depending on
their diffusional properties
1. Low vapour permeability 10-100
g/m2/24h Sd 0,3 - 10m
reinforced or having an anti-condensation layer
they require a ventilation gap over the thermal
insulation STROTEX SL PP STROTEX 110 STROTEX
140
2. High vapour-permeability 800 - 4000
g/m2/24h Sd 0,012-0,1m
made of materials of high permeability of the
water vapour they may touch directly the thermal
insulation STROTEX 1300 Basic STROTEX 1300
V STROTEX 1300 Supreme
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ROOFING FOILS
Technical parameters of vapour-permeable STROTEX
FAMILY roofing foils
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ROOFING FOILS
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)
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ROOFING FOILS
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
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ROOFING FOILS
Vapour-barrier foils according to their
diffusional properties

• Vapour-barrier foils 00.1
  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 0.23.0
  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 4.06.0
  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

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ROOFING FOILS
Wind-barrier foils WIGOFOL
Wind-barrier protects 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.
1. main roofing (asphalt roofing or bitumen
tile) 2. board roofing 3. Ventilation space 4.
wind-barrier foil (WIGOFOL) 5. therm insulation
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ROOFING FOILS
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 lt 0.3 m ? the
vapour-barrier foil Sd gt 2 m. initial roofing
foil Sd gt 0.3 m (poorly vapour-permeable foils) ?
more efficient vapour-barrier foils should be
used.
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ROOF SLOPES VENTILATION
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
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ROOF SLOPES VENTILATION
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.
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ROOF SLOPES VENTILATION

• 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
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ROOF SLOPES VENTILATION
Ventilation of usable attics
Foils of a high vapour permeability can be
applied directly on the thermal insulation
A roof with Highly vapour-permeable foil. 1.
Proper roofing, 2. Ventilation gap. 3. Highly
vapour-permeable foil (STROTEX), 4. Thermal
insulation.
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ROOF SLOPES VENTILATION
Ventilation of usable attics
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 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
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ROOF SLOPES VENTILATION
Ventilation gap size
- 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).
- 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
- 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.
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ROOF SLOPES VENTILATION
Ventilation gap size
Examples of gap sizes the gap is calculated for
one side of the slope
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MISTAKES IN APPLICATION
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.
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MISTAKES IN APPLICATION
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
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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MISTAKES IN APPLICATION
7. Lack of ventilation slot over thermal
insulation causes serious dampfening of the
insulation in roofs with poor-permeable foils or
with roof paper.
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
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
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MISTAKES IN APPLICATION
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VAPOUR-PERMEABLE FOIL INSTALLATION
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.
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VAPOUR-PERMEABLE FOIL INSTALLATION
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.
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VAPOUR-PERMEABLE FOIL INSTALLATION
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
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VAPOUR-PERMEABLE FOIL INSTALLATION
Tension
Possible methods of permeable foils tensile
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VAPOUR-PERMEABLE FOIL INSTALLATION
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
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VAPOUR-PERMEABLE FOIL INSTALLATION
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 foils nail punctures
- Installation without counter-battens may only
be performed at ones 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
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VAPOUR-PERMEABLE FOIL INSTALLATION
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
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VAPOUR-PERMEABLE FOIL INSTALLATION
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.
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VAPOUR-PERMEABLE FOIL INSTALLATION
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 blocked
3. 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
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VAPOUR-PERMEABLE FOIL INSTALLATION
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 sidel gluing tape.(This
protects against the rustle and excessive
stretching of the foil during strong winds and
guarantees free air flow)
There are two ways of the foils output, so the
drops to go out
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.
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VAPOUR-PERMEABLE FOIL INSTALLATION
Roof ridge

• Installation of the foil in the roof ridge
  depends on
• the type of foil used
• on the method of thermal insulation installation.
  
• Types of roof ridges
• Open, used when poorly vapour-permeable foil is
  applied
• Closed, used when highly vapour-permeable foil is
  applied.

Open roof ridge with ventilation gap protection
Open roof ridge
Closed roof ridge
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VAPOUR-PERMEABLE FOIL INSTALLATION
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
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VAPOUR-PERMEABLE FOIL INSTALLATION
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.

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VAPOUR-PERMEABLE FOIL INSTALLATION
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.
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.
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.
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VAPOUR-PERMEABLE FOIL INSTALLATION
Small gutter

• The gutters protect against the flowing
  condensate or leaks.
• They are usually made of
• additional pieces of foil which are placed under
  the nearest overlap
• 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
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VAPOUR-PERMEABLE FOIL INSTALLATION
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
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VAPOUR-PERMEABLE FOIL INSTALLATION
Ridge

• 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.

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
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VAPOUR-PERMEABLE FOIL INSTALLATION
Valey

• 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.

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
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VAPOUR-PERMEABLE FOIL INSTALLATION
Loft renovation installation of the foil on an
existing roof
In 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.
a. using soffit panels
b. using spacers
Method of installation of highly vapour-permeable
foil during loft renovation
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VAPOUR-BARRIER FOIL INSTALLATION
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
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VAPOUR-BARRIER FOIL INSTALLATION
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
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