Spending alot of money on ICF, and ALOT on triple pane INLINE windows but im worried about the best way to seal the wood window bucks for the TF verticle ICF's.

Any suggestions on how to seal these window bucks to be the most energy efficient I can.

NewbieJohn, are you using pressure treated 2X for window bucks? That's what I used. They have a tendency to warp and pull away from the concrete. Be sure to drive some large screws through the buck header and jambs before placing the concrete to minimize this effect. Even minimal separation of the buck from the concrete will allow air to infiltrate the house. I flashed the bucks with that sticky window flashing tape available at home centers. It sticks well to the buck if not quite so well to the foam. You'll also want to seal around the windows once installed with a foam sealer made for that purpose.

Newbie, a caution. Don't go overboard on chasing 1s and 2s of Btus of energy loss. It's not worth it. Wood has an R value around 1 per inch. That would be R 11 for a total wall thickness of 11" if you're going the entire width of the wall with the buck. That's about half of the wall R value, and considering the small percentage of area composed of bucks the total R difference isn't enough to wrapped around the axle about.

That being said, you do want to get a tight air seal around the buck. What I did was use a 2 x 6 douglas fir buck placed inside the foam as you can see in the photo. I filled in with foam rather than ripping the 2x to fit snug. The screws on the outside foam were later removed and used to fasten the window flange. I siliconed the flange to the foam. The second photo shows filling in around the window frame from the inside. On the sides and top I used low expansion foam and filled the cavity completely. On the bottom you see water pipe insulation stuffed in there. I uncurled it before I pushed it in under the window frame. It fit very snugly. I wanted to leave an open space at the bottom of the window just behind the flange to allow for possible moisture to drain out. I also did not caulk the bottom flange but did fasten it with screws. Is the bottom side of the window absolutely 100% air tight? Possibly not, but after finish trim is in place it pretty much is. I never felt any drafts through there.

Because of warping problems with PT wood, and price, I used construction grade DF. In the third photo you can see the sill seal foam I stapled to the concrete side of the buck. That foam curves back into the ICF block. I does a couple of things. One, it keeps the concrete from directly contacting the wood thus preventing condensation between concrete and wood, and it provides an air seal on the concrete side of the buck.

Hope this helps.

Mac

Mac - I like the Seal Foam...quick question whats that piece of 'all-thread' doing along the outside of the window buck attached to that 2x6?

I figured someone was going to ask!! I had a problem with wall straightness which wasn't apparent until the concrete was placed. The wall had a kink, or bend, right in line with one side of the window opening about half way between alignment braces. We didn't have any more braces to put there so I put a couple of 2 x 4s, or 6s, I think, on the inside of the wall across the two adjacent braces and the piece of LVL on the outside. There were two all threads, only one shown, that pulled the wall inward. It's tough to move the wall between two braces only about 6' to 8' apart! It pretty much straightened the wall. I think the alignment problem was partially caused by the over height corner blocks I wrote about some time ago. This window was only about 6' from the corner.

Looking at the pic again I see it is a 2 x 6 on the inside. There were two but only one is visible. The all thread nuts were cranked down far enough to bend the 2 x 6s on the inside about an inch or more!