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DoneItBefore

@eastlink.ca
reply to doechsli

Re: Spray Foam or Batts

Why not use what you want and then just strap the 2x4s.
The strapping is cheap[1x3]and allows room for running wires as the strapping is applied across the 2x4s.It also allows a bit af breathing space[healthier]and also noise reduction.
Also you might want to put a plastic[6mil] vapor barrier on the outside of the insulation instead of inside.Not the norm but Mike Holmes endorses it.[from Holmes on Holmes]He endorses it because it truly is a vapor barrier for your inside as well as your choice of insulation,whereas the normal way only keeps moisture from the drywall leaving any and all insulation susceptable to leaks.
Just a thought.I have done it both ways and keep in mind that spray foam is nearly impossible to remove intirely.
One can also run some abs/pvc tube or conduit tube for future running of wires when spray foam has been applied.
Good luck!!



LazMan
Premium
join:2003-03-26
canada

Vapor barrier placement; if one is required, is dictated by temperature - it goes to the warm side of the wall - basically, if you spend more time heating, barrier goes on the inside; if you spend more time cooling, it goes to the outside...

Holmes on Homes was filmed around Toronto, Ontario, Canada... Hence vapor barrier on the inside.


MaynardKrebs
Heave Steve, for the good of the country
Premium
join:2009-06-17
kudos:4

1 edit

said by LazMan:

Vapor barrier placement; if one is required, is dictated by temperature - it goes to the warm side of the wall - basically, if you spend more time heating, barrier goes on the inside; if you spend more time cooling, it goes to the outside...

Holmes on Homes was filmed around Toronto, Ontario, Canada... Hence vapor barrier on the inside.

It depends on where the dewpoint is inside the wall cavity, which is a function of the temperature differences inside to outside, and the type of insulation & thickness. Foam sprayed in a wall cavity up against the sheathing in sufficient thickness will change the dew point in the wall to the point where water can't condense. You then fill the remainder of the cavity with batt insulation and drywall right over the batts without a poly vapour barrier. This gives the wall assembly what it needs - the ability to 'dry' to one side - in this case the interior.

A former classmate of mine is the principal @ www.buildingscience.com You can read about insulation there. Joe is one of, if not THE leading expert on this in North America.


LazMan
Premium
join:2003-03-26
canada

Agreed, the building science methods are excellent... I was just simplifying. Vapor barrier to the warm side; whichever that may be...