Sentence 9.25.3.2.(2)

Intent 1:

To limit the probability that the performance of polyethylene sheets will fall significantly below expectations, which could lead to an inability to resist loads induced by air pressure differences, which could lead to the sheets rupturing or tearing at fasteners, or becoming prematurely brittle, which could lead to the failure of the membrane.

This is to limit the probability of a loss of airtightness, which could lead to:

• excessive heat loss or gain due to air mass transfer,
• excessive air infiltration and exfiltration,
• excessive airborne vapour transfer from interior above ground and exterior below ground, or
• precipitation ingress due to air pressure differences.

This is to limit the probability of condensation or the accumulation of water, which could lead to deterioration, which could lead to compromised structural integrity of assemblies acting as or protected by environmental separators, which could lead to harm to persons.