Quote:
Originally Posted by topfiverecords
Did you cover the spray foam?
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The only areas you need to worry about (if you are drywalling the basement ceiling) are the joist bays that serve the return air system, although dropped bulkheads can make it pretty tough to determine which of these may be in play within the R/A system (and thus require thermal barrier treatment).
Thermal Barrier in these areas is most easily achieved by covering the spray foam with a layer of mineral fiber insulation (i.e. "Roxul").
You do not need to spend the additional money on the "Safe 'n' Sound" product, Standard R14 is compliant for the intent of the code.
The idea is that this product will allow your fire detection systems to activate before there is any serious risk of the Closed Cell foam being heated to the point where it begins to "off-gas" and circulate through your forced air heating system; thus suffocating you in your bed at 4 Am.
My Drywall Company uses 2-lb (closed cell) foam in every house we do (in the rims, block ends, and cantilevered areas). It's the only way to be sure that these spaces are properly air sealed.
With the envelopes as "tight" as they are these days, any little leak in the air/vapour barrier is magnified to a point of stupidity.
It's like a leak in your cooling system in a 1979 Chevy half ton that you're still driving in the early 90's. Replace the top hose? One of the ones to the heater core blows. Replace this and the radiator fails. Repair/replace this and the heater core goes.
In any pressurized system,
the weakest link will always be the point of failure for the
entire system.
And this is exactly what we are doing with envelopes these days.
Creating a pressurized system.
This is why I pay the extra money to foam all of these "problem" areas.
I never have to deal with..."my floor is cold", "my waterline to my fridge is frozen", "my toilet won't flush properly".
All of these things that can get "covered up" before you know that there is a problem and lead to costly re-work down the road.
Well worth the minimal cost ($800-$1000 on a typical "skinny" [17x50 infill], in the big picture.
Hope this helps.
All for now, Ron
