I am in the Chicago area (CZ 5) and we are using a modified version of IECC 2012. Our exterior wall is a masonry veneer wall and we are using 2x6 wall studs for framing, allowing R-21 insulation in the stud cavities. Structurally, the wall could be built with 2x4 studs but it was decided that going with 2x6 and R-21 would be more cost effective than using 2x4s with 2" of rigid on the outside.
Some of the headers in this wall only need a double Microllam (3-1/2"), and the rest of the space can be filled with 2" rigid insulation. Where is the best place to put this insulation? I've seen some details that show the rigid sandwiched between the two 1-3/4" Microllams. This would support both sides of the 2x6 wall above and prevent twisting. But I think the double Microllam has more structural integrity when the two are nailed together, then putting the rigid on one side or the other. SInce the floor joists only need 3-1/2" of bearing, I don't think twisting is a concern. So is it better to put the rigid on the interior side or exterior side of the wall. My inclination is to put the Microllams to the outside, to provide additional support at that side, since that is where the windows/doors in the opening have their nailing flange.
Does this make sense, or are there other considerations I should be factoring in?
Posted Fri, 01/31/2014 - 11:10
Edited Mon, 02/03/2014 - 08:40
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