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The
impact of Canada's new VOC regulations on under-slab vapour
barriers
When
making a vapour barrier decision, how do I prioritize the
relative importance of permeance vs. puncture resistance vs.
tensile strength?
By
Brian Rooney
It's easy to understand why experienced decision-makers might
fall into the trap of over valuing the virtues of strength.
Most have had the experience of seeing weak plastics in the
field that visually look like swiss cheese. Intuitively one
might reason: if you use stronger material, then surely the
problems go away.
In earlier essays, I made the flat,
assertive statements that permeance is the mission-critical
performance characteristic of a vapour barrier.
What does the term "mission-critical"
really mean? It means that permeance is the reason why you
buy a vapour barrier for your building.
By analogy, the mission-critical
performance characteristic of a car is its ability to transport
you from one point to another safely, reliably and affordably.
A really great-looking, powerful
car that can pass anything on the road except a gas station
or a repair shop probably isn't going to make your short list.
Permeance is a measure of whether
the vapour barrier is even capable being effective.
It simply doesn't matter how strong
an ineffective vapour barrier is. Don't expect its permeance
to improve in the field!
If a membrane is damaged from abuse,
it can be repaired. If it is repaired properly, the system
still works effectively.
If damage isn't repaired properly,
there might be a flooring problem. However, the problem will
be isolated to a small area directly above the damaged areas.
In contrast, if a membrane's permeance
is too high to be effective, there can be a flooring problem
over the entire footprint. In that case, it literally didn't
matter whether there was any damage or not.
When you are evaluating alternative
products, first determine whether the permeance meets your
requirements. If it doesn't, then: FULL STOP!
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The
breakthrough family of single-install, multi-function, fire-rated,
waterproof, sound proof, hurricane-resistant, high movement
expansion joint sealant technology will be discussed and contrasted
with existing technologies and principles of the industry.