Installing Windows Over Rigid Insulatn
Rampside
| Posted in Construction Techniques on
I’m installing new Andersen windows on a 50 yr old house. All existing siding is to be removed. The plans call for new 1 inch DOW insulation boards over the old sheathing. The windows are to be fastened over the DOW boards. Are longer roofing nails the “best ” way to do this?
Replies
Rigid foam has really taken off around here, people want to heat their house with a match. 1 1/2 foam is becoming popular so I build out the opening with 2x4's then foam around the build outs and use regular siding nails to fasten the window. In your case of 1" foam use 2 layers of 1/2 treated plywood nailed and possibly glued (ACQ nails would be best.)
Just like the Stilletto said, you need firm fqasstening for the windows, not directly on foam.
You could also be creating another problem doing this. what part of the country is the job in? You have no info in your profile to be able to tell.
In a heating climate, if you place the foam on the exterior side of the wall, moisture can be caught in the stud spaces to eventually lead to mold and rot. if you have a VB on the intyeriopr portion of the wall, you would be violating the rule to never have a double VB and would definitely trap water in the wall
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Y, It's in New Jersey. Is there a way to install the exterior foam & not have a "MOLD" problem? I'm going to check with DOW on this also. How can they recommend this product if there will be a mold problem?
They can recommend a product to do a certaain job when used a certain way. Any product can cause a problem when used indiscriminately.jersey is a pretty moderate climate though, barely a heating climate, so don't worry about it.
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Rampside,
Find a stucco installer who works with modern two-part systems and talk to him about how to do it.
They use mortar applied with trowels with 1/2" or 3/4" hemispherical notches cut in them. The mortar is usually just the stucco base coat It is not spread. The foam adheres to the mortar ridges, so there is a small air space between the ridges for a drainage plane.
Flashing details are critical here.
Ron
Isn't there a product that you can staple-up that channels any moisture away. ..... I vaguely remember seeing something by CORAVENT(?) that you put along the starter course and at the eaves. Was it them or??PS Is there another product that is made of thin plastic strands that form loops, sort of an open weave synthetic sanding pad. It comes in panels and can be used under siding?...... BUT isn't the real problem keeping the interior moisture from migrating into the stud cavities?
Rampside,
I think you are right about the breather material but I know nothing about it.
In my view, the problem is to get rid of any water that might condense on the inner face of the foam. You need some sort of drainage plane.
Ron