Replies

1. 
   davidmeiland | Aug 16, 2006 04:57pm | #1

   That's gonna be fairly hard, if I'm imagining it correctly. If you could put the felt over the foam then you'd have an easy time lapping the felt over z-metal flashing that you have made to go over the windows. If the felt is behind the foam then maybe you can somehow slide the z-metal up into place behind both, right before you put the window in.

   I have not installed windows very often with the trim attached as you describe--much easier and better in my opinion to order them with nailing fins, waterproof to the fins, and then add your trim. With the casing already on there then you're probably depending on caulk to 'flash' the sides.

2. 
   RayMoore2G | Aug 18, 2006 05:46am | #2

   We oversize the window opening and line them with wider material that brings the windows out to the desired plane. We slope the bottom piece of our bumpout to help form a self draining pan under the window out of peel and stick membrane. Make sure your head flashings with end dams are well done at the top.

   Above all else, remember that window is a French word that means "water inside your house". All windows can leak, either now or later. Install them so their leaky nature never causes a problem ever. Always use pan flashings and head flashings with end dams.

1. 
   qwkbrnfox | Aug 18, 2006 08:27am | #4

   Hi Ray,Interesting idea. What do you use for the liner? 2x on the flat, ripped?

1. 
   RayMoore2G | Aug 18, 2006 03:46pm | #6

   yes, we oversize by 3" in width and 3.5" in height to allow for the slope on the bottom. For masonry, we push the liner out to the face of the foam and for siding we push it out to the face of the furring strips that I will describe below. The idea is to get the window out to a plane that doesn't introduce any architectural issues related to the thickness of the foam and or furring strips.

   For a rainscreen with siding, we use 3/4" treated furring strips, attached through the foam and into the studs with long screws. The siding then attaches to the 3/4" furring strips. The only issue with this method is a code requirement for 1" penetration into the substrate when installing siding. We have not had problems but usually use 2 screws at each attachment location when hanging the siding.

   We use a rubberized asphalt membrane under 2" of polyisocyanurate. I coined a new acronym for this method because I don't like PERSIST as a name for this system. My name for it is REFORM. This stands for Rigid External Foam Over Rubberized Membrane. I think we should REFORM the entire building industry.

3. 
   mike2006 | Aug 18, 2006 08:08am | #3

   If you are planning to drain to the tarpaper behind the foam are you going to construct the rain screen behind the foam as well?  If the RS is going to be exterior to the foam why not just drain to that?  It seems as if that would make the flashing details much simpler.  The reason I ask is we are in the process of designing our new house and would like to have rigid foam exterior to the shearthing, tape/flash the foam and use that as our drainage plane.

1. 
   Ashgrove | Aug 18, 2006 03:18pm | #5

   According to Building Science info for the cold region-we are in Northern Iowa, the order is sheathing, drainage plane, foam. They then highly recommend a rain screen installation for fiber cement but do not offer any info on how to put it all together, at least that I have found.