# How to attach rigid polyiso to exterior brick wall



## bluefoxicy (Nov 5, 2012)

Is there a method to attach rigid polyiso insulation directly to a brick wall? Can I use Loctite Foamboard Adhesive and plastic masonry fasteners? I assume adhesive alone is not appropriate for permanent installation in this application.

I want to insulate above the block and between the columns on this wall. Wall is entirely brick with chicken wire nailed to it to hold the concrete finish.










Other questions:


This isn't a moisture barrier. Do I need to extend the roof flashing overtop the polyiso?
How do I attach siding or finish over this? Do I need to place a substrate and stucco over top, or should I just run vinyl siding between the columns?
As-is, paneling and siding will leave the bottom of the area open and sloped away, which will allow any moisture/water making its way behind the panels to drain. That's a hard requirement, yes?

The current R-value of that wall is 2 feet of brick--R1. I'm hoping to add 2 inches of Polyisocyanurate for an extra R13.1. This will leave about 2 feet width uninsulated, but it doesn't matter all that much.

Insulating inside is infeasible. Parts of the inside have stud wall; other parts are stucco and afford only the width of a 30-inch doorway (stairwell). I have applied insulation where stud walls exist (part of the bathroom; kitchen; built a new one in the master bedroom).

Thanks.


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## Gary in WA (Mar 11, 2009)

Looks like your neighbor moved.... 

"


This isn't a moisture barrier. Do I need to extend the roof flashing overtop the polyiso?----------------Yes. Your first read; https://buildingscience.com/documen...sulation-masonry-walls-wood-framed-walls/view




How do I attach siding or finish over this? Do I need to place a substrate and stucco over top, or should I just run vinyl siding between the columns?
As-is, paneling and siding will leave the bottom of the area open and sloped away, which will allow any moisture/water making its way behind the panels to drain. That's a hard requirement, yes?"--------------------------------- attachment of furring strips and load rating;https://buildingscience.com/documen...installed-over-exterior-rigid-insulation/view
Gary


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## bluefoxicy (Nov 5, 2012)

Gary in WA said:


> This isn't a moisture barrier. Do I need to extend the roof flashing overtop the polyiso?----------------Yes. Your first read; https://buildingscience.com/documen...sulation-masonry-walls-wood-framed-walls/view


So I see. Lay 2x4 flat; bolt to the wall with tapcon; place 1.5 inch polyiso between 2x4; then turn sideways and install another layer of polyiso over that, secured in place by furring strips screwed into the 2x4 studs. This should only fasten wood-to-wood through 1.5 inches of rigid foam insulation, avoiding issues with fastener movement through thicker layers of rigid foam sheathing.

It looks like 1.5 inch polyiso isn't available here anywhere for now. Can't even order it. R9.6 per inch vs R7.5 per inch pink stuff at $24 per 4x8. That would give R15 rather than R9.6, in total, which is more and thus acceptable (although R19.2 of polyiso would be better).

I am uncertain what the blue sheet in the diagram represents. The text does not elucidate this, and no such thing is present on recently earthquake-damaged structures here which have lost some of their siding and insulation.

That's a whole lot more information that I was expecting. I'm going to need to read and re-read that to digest it fully. Even my current contractor doesn't seem to understand how many things work beyond his long experience in construction; he's not an engineer.


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## Gary in WA (Mar 11, 2009)

IF your basement is not insulated on that side now... good time for some waterproofing/rigid insulation... check with your local Building Inspector. They may want you to bring the wall R-value up to code...

Gary


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