Through my research and the people I talked to, I will go the route of vinyl window bucks through Nudura. I am NOT a fan of treated wood sitting next to concrete. Especially since the concrete within ICF is releasing moisture from curing for over at least 1 year.

You can wrap the wood with a moisture barrier to prevent direct contact between wood and concrete. I had a bunch of fastfoot scraps left over and stapled that to the backside of the window bucks before inserting them into the ICF.

I am NOT a fan of treated wood sitting next to concrete

Isn't that what treated wood is for? If you put some thought into how you do it in the first place, there is no need to worry. Two contractors, both of whom I trust, tell me they have looked at treated bucks in concrete as much as 12-15 years down the line and there are no issues whatsoever. And that is in the Pacific Northwest where moisture is always a problem.

Posted By ICFHybrid on 18 Feb 2012 10:22 PM

I am NOT a fan of treated wood sitting next to concrete

Isn't that what treated wood is for? If you put some thought into how you do it in the first place, there is no need to worry. Two contractors, both of whom I trust, tell me they have looked at treated bucks in concrete as much as 12-15 years down the line and there are no issues whatsoever. And that is in the Pacific Northwest where moisture is always a problem.

The reason they came up with "treated" was to address rot, it did NOTHING to address bowing, twisting, splitting and warping. Sure the treated wood won't rot like untreated wood but it will surely do a host of other things like bow, twist, split and warp.

I would like to see the long term results of wood sitting on top of the concrete walls or within the window bucks. 15-20 years of treated wood sitting there and the results of that.

but it will surely do a host of other things like bow, twist, split and warp.

All wood has the potential to do that, yet wood is still used extensively in construction. You have to put some thought into how it is done. I didn't like the idea of treated bucks either, but I have 70 openings, most of which are very large and if you anchor, brace and fasten them correctly, there is nothing to fear.

What is the downside of not using window bucks?  That is, using temporary untreated wood bracing for the openings and then attaching the windows to the concrete through the foam.  Yes, I know that Tapcon screws will have to be used to attach the windows but that would be one way around using treated wood and other expensive options.  Installing Tapcons before the concrete gets too hard should not add to labor that much.  Of course, this idea might not be great for wood windows unless a membrane is used to protect them from the water in the concrete.

Posted By Alton on 20 Feb 2012 12:32 PM
What is the downside of not using window bucks?  That is, using temporary untreated wood bracing for the openings and then attaching the windows to the concrete through the foam.  Yes, I know that Tapcon screws will have to be used to attach the windows but that would be one way around using treated wood and other expensive options.  Installing Tapcons before the concrete gets too hard should not add to labor that much.  Of course, this idea might not be great for wood windows unless a membrane is used to protect them from the water in the concrete.

Windows on our secure buildings are handled that way all the time because the owners usually don't want any wood on the building envelope. A temporary wood buck is used and then removed once the concrete cures. Windows are then attached directly to the concrete.

Posted By Alton on 20 Feb 2012 12:32 PM
What is the downside of not using window bucks?  That is, using temporary untreated wood bracing for the openings and then attaching the windows to the concrete through the foam.  Yes, I know that Tapcon screws will have to be used to attach the windows but that would be one way around using treated wood and other expensive options.  Installing Tapcons before the concrete gets too hard should not add to labor that much.  Of course, this idea might not be great for wood windows unless a membrane is used to protect them from the water in the concrete.

Feasible for the those whose do ICF buildings on a regular basis. For the one time DIY, or if the owner is buying all the materials himself, not necessarily a good option from a cost standpoint. What's the value in buying 2 x 10s and 2 x 12s you can't use for something else later in the construction? I was able to pretty much reuse the 2 x 4s I used in bracing the bucks because interior walls use a lot of short 2 x 4s, but I would have had little use for 4 and 5 ft long 2 x 12s.

dmaceld, You can burn them in a 55 gal drum and keep warm. ;-)

Burning is ok if the wood is not treated.

Yep, more fodder for the fire being stoked by those who argue ICF isn't worth the cost!!

Couple comments:

Don't forget about the finish and trim on the inside of the house. If you have a foam surround around the inside of the window/door opening, you have nothing to nail sheetrock/trim to. The v-buck also has that same issue. A few builders I talked with use the V-buck for it's ease and labor savings, but say they'd prefer to use a 2x buck for nailing windows/trim/drywall, etc. They also mention that with the v-buck, sometimes concrete will get between the vinyl and the foam, and when a screw hits that concrete, it stops it and strips out the vinyl.

99% of the twisting, bowing, checking, etc will happen in the first month when that wood dries out and hits the sun. Once it's in you walls I doubt it'll move. Think of all the decks that are sitting in the elements. Those PT deck boards shrink a 1/4" in the first month or so, and then that's where they live.

Lbear, it seems like things are either "always" or "never" to you. . . . . things are NEVER "always" or "never"

Treated 2x lumber is fine for sub-bucks. It will get tapcons, and as long as its done correctly will not warp and twist.

Use a 1x window buck over the 2x to set your window flange on. Use a good caulk like OSI Quad, not the cheap stuff.

As long as you get your rough openings correct, everything will fit nice and snug and you wont have leaks.

No reason to over think this part of the job.

If you can't get the window openings correct you should be hiring a professional installer.

One suggestion I got by my local rep on the interior trim attachment was to use 1/2" osb/plywood ripped about 1/4-1/2" shy of the window trim width. Same along the base boards. Then screw the osb to the forms, but your drywall against it and finish that way. You then have osb/plywood to nail your trim too. Or just do gyp returns with a nice sill and no worries.
The one concern I do have with the large windows sitting on foam is the weight. I am working on a project were the window is 4 wide, each 30x72 tall, triple pane. HEAAVVVY window. I think I will just do a 2x12 solid across the window opening unless there are better ideas?
Also does anyone have good suggestions on flashing/tape products for taping off the windows to EPS foam? Do most people do reglet head flashing?

Posted By dmaceld on 20 Feb 2012 02:31 PM

Posted By Alton on 20 Feb 2012 12:32 PM
What is the downside of not using window bucks?  That is, using temporary untreated wood bracing for the openings and then attaching the windows to the concrete through the foam.  Yes, I know that Tapcon screws will have to be used to attach the windows but that would be one way around using treated wood and other expensive options.  Installing Tapcons before the concrete gets too hard should not add to labor that much.  Of course, this idea might not be great for wood windows unless a membrane is used to protect them from the water in the concrete.

Feasible for the those whose do ICF buildings on a regular basis. For the one time DIY, or if the owner is buying all the materials himself, not necessarily a good option from a cost standpoint. What's the value in buying 2 x 10s and 2 x 12s you can't use for something else later in the construction? I was able to pretty much reuse the 2 x 4s I used in bracing the bucks because interior walls use a lot of short 2 x 4s, but I would have had little use for 4 and 5 ft long 2 x 12s.

I removed all wood forms (untreated) from my window openings and will screw the windows directly into the concrete with Tapcons. I don't really understand the cost issue - it's about $20/window for my medium sized windows so it won't noticeably add to the budget. I'll plan to turn it into mulch for landscaping once I finish with the house.

Using 2x10's and letting the 1/4 inch overhang on the outside. It will be covered by the siding anyway. Did the same thing on the truss plates as they will be covered by the soffit

Not to hijack this thread but the builder I'm considering for my ICF home uses LSL bucks from Prebuck Products. Aside from the previous comments about treated wood bucks, any thoughts on these?

Prebuck is a good product. We recommend it for use with Polycrete ICFs.

I've been using Pre-buck for a number of years now.
It is an all around good product for the ICF builder and all other trades.
You can get it knocked down for shipping or pre-built.
The dovetailed inner surface holds the concrete very well.

We use it for sill plates and on top of gable walls as well.
We just poured a elevated 4' x 40' ramp at a 3/12 pitch. No other shoring was, just the LSL board glued to the icf wall. Only a 1/16” deflection.

I have several cut off pieces laying around outside no real changes, these cut off pieces see rain and sun.
The owner of the company is a honest and straight forward guy, good to work with.

Why hasn't anyone mentioned Fox Buck? I used them, thought they were great! Just had a Blower door test done .59ach@50Pa, definitely very few leaks around windows and doors.