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The latest membranes from Permavent are three layered non woven polypropylene either side of a high tech micro-porous functional film. This functional film is specially treated to prevent rain and moisture from entering the roof when in use, yet allowing water vapour and condensation out of the roof space. Permavent combines performance with strength to produce strong, lightweight membranes that fight condensation.
Our versatile range for use as a roofing underlay's or as a house wrap on timber frame can also combine with 'Reflect' our very latest thermal conductive vapour control layer for great performance.
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ECO
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BLACK
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MAX
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BASE WEIGHT, g/m2
This indicates how much the product weighs in grams per metre squared. It does not indicate performance.
NOTE: Performance is not determined by weight alone (in the same way that steel and tungsten compare) |
90 |
115 |
140 |
TENSILE MD/CD, mean N
This test shows how easy it is to rip the membrane. The higher the number the better the performance. NOTE: Tensile strength has to be matched by nail tear resistance to show true performance* |
161.5 |
208 |
254.5 |
ELONGATION MD/CD, mean%
This test shows the percentage of flexibility before the membrane breaks and is a good indicator of how easy the membrane is to work with before failure occurs* |
70.5 |
111.5 |
93 |
NAIL TEAR STRENGTH MD/CD mean N
This test shows the real strength of the product and indicates how much pressure is required to pull a nail through the membrane. It is measured in Newtons* |
159.5 |
161.5 |
180 |
MVTR, g/m2/24hr Water vapour permeability
This test indicates how much moisture (under test conditions) can pass through 1m2 in 24hrs which is the main function of a breather membrane. The higher the better. |
1960 |
1373 |
1343 |
WATER TIGHTNESS, cm H20
This test shows the membranes ability to keep water out of the roof (a pass means it was only tested to 100cm). This test indicatesr of how good the functional film is when compared with the vapour permeability (i.e lets moisture out yet stops water getting back in). Some air membranes can suffer from low water resistance! |
527 |
>450 |
>600 |
VAPOUR RESISTANCE, MNs/g-1
Because the results of the water vapour permeability test can vary (due to the conditions created) the government has chosen this more reliable test as its bench mark and all breathers must be below 0.25MNs/g-1. Independent tests indicate that 0.16MNs/g-1 should be achieved but generally the lower the better. |
0.11 |
>0.15 |
>0.15 |
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Breather membrane
