Description
Knauf Breatheline is a flexible sheet material consisting of a
breather membrane with a polypropylene non-woven coating on both
sides. The upper surface has a light grey anti-glare finish.
Application
Knauf Breatheline is used as a vapour permeable underlay in
sealed and ventilated pitched roofs. It can also be used as a
vapour permeable membrane in timber frame construction.
The high vapour permeability of Knauf Breatheline means that the
roof space does not have to be ventilated to remove water vapour.
This keeps the roof space warmer and makes it less prone to
condensation and the build up of dust and dirt from the outside
air. Knauf Breatheline can be used whether the thermal insulation
is placed at ceiling level or rafter level.
Knauf Breatheline is non-wicking and so can be laid in direct
contact with insulation and roof boarding with no risk of moisture
penetration.
Certification
Knauf Breatheline is certified by the following British Board of
Agrément
Certificates
- 03/4011– for timber frame
- 03/4014 – for unsupported or fully supported roof tile
underlay
- 03/4017 – as underlay in unventilated cold pitched roofs
Durability
Knauf Breatheline is odourless, rot proof, non-hygroscopic, does
not sustain vermin and will not encourage the growth of fungi,
mould or bacteria.
Knauf Breatheline has excellent tear and nail strength, yet
remains flexible, even at low temperatures.
Environmental
Knauf Breatheline is free from CFCs, HCFCs and any other
material with ozone depletion potential in its manufacture and
content and represents no known threat to the environment. Knauf
Breatheline is 100% recyclable
Handling and Storage
Knauf Breatheline is light in weight yet easy to handle, cut and
install.
Knauf Breatheline is supplied wrapped in polythene, which is
designed for short term protection only. For longer term protection
on site, the product should be stored either indoors, or under
cover and off the ground.
Product Data
| Length (mm) |
Width (mm) |
Area per Roll
(m2) |
Roll Weight (kg) |
Water Vapour Resistance
to BS 3177 (MNs/g) |
(Sd value m) |
| 50 |
1500 |
75 |
10.5 |
0.22 |
0.02 |
All dimensions are nominal
Physical Properties
| Test |
Method(1) |
Mean result |
Units |
| Mullen burst
strength |
BS 3137 |
552 |
kNm2 |
| 1 metre head of water for
24 hours |
BBA(1) |
no penetration |
|
| Water vapour
permeability |
BS 3177, 25°C/75% RH |
935 |
gm2day |
| Water vapour
resistance |
BS 3177, 25°C/75% RH |
0.22 |
MNsg |
| Resistance to water
spray |
T1/15(2) |
pass |
|
| Hydrostatic pressure -
mean |
BS EN 20811 |
4.53 |
kNm2 |
| Hydrostatic pressure -
minimum |
BS EN 20811 |
3.08 |
kNm2 |
(1) Based on MOAT No 27 : Method
5.1.4.
(2) BBA test method.
Physical Properties - Directional
| Test |
Method(1) |
Mean
results |
Units |
| |
|
long(1) |
trans(2) |
|
| Tensile strength (N 50
mm2) |
BS 2782-3: 320A |
|
|
|
| – unaged (control) |
(100 mm min) |
252 |
159 |
N 50 mm2 |
| – aged(3) |
|
250 |
158 |
N 50 mm2 |
| – water
soak(4) |
|
254 |
153 |
N 50 mm2 |
| – wet
strength(5) |
|
267 |
179 |
N 50 mm2 |
| – UV 200 light
hours(6) |
|
207 |
138 |
N 50 mm2 |
| – UV 500 light
hours(6) |
|
108 |
64 |
N 50 mm2 |
| Elongation at break |
BS 2782-3: 320A |
|
|
|
| – unaged (control) |
(100 mm min) |
23 |
49 |
% |
| – aged(3) |
|
18 |
35 |
% |
| – water
soak(4) |
|
25 |
50 |
% |
| – wet
strength(5) |
|
22 |
51 |
% |
| – UV 200 light
hours(6) |
|
13 |
32 |
% |
| – V 500 light
hours(6) |
|
5 |
31 |
% |
| Resistance to nail
tear |
MOAT 27 : 5.4.1 |
|
|
|
| – unaged (control) |
|
95 |
73 |
N |
| – aged(3) |
|
71 |
64 |
N |
| – water
soak(4) |
|
84 |
94 |
N |
(1) Longitudinal direction.
(2) Transverse direction.
(3) Heat aged at 70°C for 56 days.
(4) Water immersion at 23°C for 56 days — tested
dry.
(5) 24 hours at 23°C — tested wet.
(6) UV aged — 4 hours UV at 50°C followed by 4 hours
condensation at 50°C.
Service Performance
| Test |
|
Method |
Mean result |
Units |
| Low temperature
flexibility |
|
MOAT 27 : 5.4.2 |
–21 |
°C |
| Resistance to water
penetration(Eosin test) |
|
BS 4016 |
pass — no staining/wetness |
|
| Puncture resistance |
|
BBA T1/01(1) |
satisfactory |
|
| Resistance to wind
loads |
|
BBA T1/03(1) |
|
|
| 350 mm batten
spacing |
– vertical |
|
≤1.5 |
kPa |
| 330 mm batten
spacing |
– vertical |
|
≤1.0 |
kPa |
| |
– horizontal |
|
≤1.0 |
kPa |
| 300 mm batten
spacing |
– vertical |
|
≤2.5 |
kPa |
| |
– horizontal |
|
≤1.5 |
kPa |
| 250 mm batten
spacing |
– horizontal |
|
≤2.5 |
kPa |
(1) BBA test methods.