Anyone have any "innie" or interior mounted window details? Ideally something for an ICF wall (6" core).

Also, can one use heat treated construction grade Douglas Fir instead of treated lumber for the window bucks? I assume a 2x8 with the lumber being mounted flush with the interior EPS, leaving 2 5/8" of exterior EPS to provide a thermal break.

You can use pretty much any type of wood for a window buck if you provide a moisture barrier between the wood and the concrete. The moisture barrier can be as simple as 6 mil polyethylene plastic stapled to the back of the wood buck. A moisture barrier isn't required if you use pressure treated lumber, but still isn't a bad idea to have something between the wood and concrete. I used treated yellow pine bucks with left over FastFoot fabric stapled to the backside.

A 2x8 is only 7-1/4" wide. How are you going to use that to span across the 6" concrete core plus the 2-5/8" foam on the inside? What you are proposing would likely require a 2x10 (9-1/4" wide) ripped down to 8-5/8".

Posted By arkie6 on 22 Oct 2012 12:36 PM
You can use pretty much any type of wood for a window buck if you provide a moisture barrier between the wood and the concrete. The moisture barrier can be as simple as 6 mil polyethylene plastic stapled to the back of the wood buck. A moisture barrier isn't required if you use pressure treated lumber, but still isn't a bad idea to have something between the wood and concrete. I used treated yellow pine bucks with left over FastFoot fabric stapled to the backside.

A 2x8 is only 7-1/4" wide. How are you going to use that to span across the 6" concrete core plus the 2-5/8" foam on the inside? What you are proposing would likely require a 2x10 (9-1/4" wide) ripped down to 8-5/8".

Thanks for the info. Yes, a 2x10 ripped down would work better. That way it would sit over the 6" of concrete and over the 2 5/8" of foam on the interior.

Have you ever used or heard anything about those "Gorilla Bucks"? They have some that use HardiBoard, which is more resistant to termites and water damage.