Posted By smartwall on 27 Feb 2016 05:50 PM
The Fox bucks are really geared toward external window and door attachment, Your building an energy smart house but you install the most energy intensive product {windows} on the outside of the wall. Why? If your going to install your windows inside the wall surface, and I hope you do, the Logix buck is a better choice. The Fox buck uses a standard web from the standard block which leaves you only the side of web to attach your windows.

perhaps they've changed it since then? I'm going to attach my windows to the middle of the buck using the side-to-side webs (and/or possibly the concrete itself). it would be nice to have a web going long-ways along the middle, but the every 8" webs should be fine. I guess time will tell.

TexasICF, I referred to Fox, Logix, et al. bucks as commercial bucks since they are manufactured by a commercial vendor and one purchases them...as in contrast to bucks that you personally create from treated lumber onsite for about 1/4 the cost and have a much better end result if you know what you are doing.

For folks new to ICF or not in the business, commercial bucks are likely a better choice. However, thinking that you will get any measurable energy performance improvement by using commercial bucks is wishful thinking (and perhaps a wasteful expense) as the exposed heat transfer area of bucks are miniscule as compared to the other building heat transfer areas (i.e., ceiling, doors, floor, walls, and windows), which unlike the buck area, are actually included the ASHRAE or ACCA MJ8 heat transfer analysis... Or perhaps another way of thinking about this...11" of 2x lumber is R15.6...way higher R-value than any window that you can possibly purchase... 8.5" of 2x lumber plus 2.5" of EPS is R22.1...slightly higher R-value than an ICF wall with 6" concrete core and 2.5" thick EPS forms...

Posted By ronmar on 27 Feb 2016 10:24 PM
Pacificstart, what purpose would the flashing serve?

I guess to prevent potential leaks going behind the window frame on the inside of the building. I realize the EPS itself is supposed to be more or lease impermeable to water but I'm thinking that a leak hitting the concrete wall will somehow make its way on the inside. I did not represent the siding in my drawing but obviously the flashing would have to extend beyond that.

You just need to properly flash the window after installation to avoid having any issue with moisture or outdoor air infiltration.

I agree with Sailawayrb. You need to properly flash wood bucks and foam. Bad flashing details will harm wood and foam. Check out plain eps used for dock flotation, water will change the product over time. Any one reading one of my post knows that I like to use my time wisely. Wood bucks allow me to build them off site in my shop .I want to spend as little time with pieces at the job. I can also tell you that the foam bucks are probably the most profitable product for the manufacturers. I'll stick with wood more economical when you factor every cost.

There is plenty of fastening for your windows inside a Fox Buck. The tie is easily found. We do it all the time. When bringing the window inside the wall rather than on the outside surface, make sure you allow room to taper the sill. I sell Fox, I think it is the best. They have a big strong tie with a lot of fastening surface and a good interlock that is both easy to install in all conditions and locks together tightly. There is nothing worse than trying to get dirt and small stones stuck or frozen in those small interlocks like some of the other blocks have. We don't tape the Fox buck in place a lot of times, as you do more you cut back on the tape but I've never had any issue with the tape I'm using sticking in any weather. Blocks aside find the guy (rep) who you can work with. It sounds easy. Stack em. Brace em. Fill em. For your first job it would be good to have a tech there.

Yea, I was just using tape to place bucks in the rain yesterday(duck brand clear packing tape works great). Building thru the winter in the pacific northwest, the block is rarely dry But the block doesn't really absorb water, so on horizontal surfaces I just wipe away any standing water before I tape. Vertical surfaces don't hold enough water to worry about and any water there just squeegees out when I rub the tape flat... In my case, the tape is really only to hold the bucks in place till the foam/glue dries as I am foaming mine in place. Of course some do not do that, and the tape should work fine until the blocking is installed. None of the tape I have used so far has come loose anyplace I have used it...

The hardest part is finding the end of the tape on the roll and getting it peeled back up when I let it fall back onto the roll

Posted By sailawayrb on 27 Feb 2016 10:58 PM
Or perhaps another way of thinking about this...11" of 2x lumber is R15.6...way higher R-value than any window that you can possibly purchase... 8.5" of 2x lumber plus 2.5" of EPS is R22.1...slightly higher R-value than an ICF wall with 6" concrete core and 2.5" thick EPS forms...

ok, so I'm sure someone can correct me if I'm wrong, but I think this is wrong (unless I am misunderstanding what you're stating). What you state would be true if the only exterior exposed area of the wood buck is the outside edge, and if the only inside exposed area is the inside edge (like a 2x used in a wall frame)

however, that doesn't consider the width of the window casing is all that really matters. meaning, the exposure of the wood buck to the cold will be on the top of the outside (under the sill), have approx 3, maybe 4 inches of distance to travel, then every inch thereafter will be exposed to the inside. So, from what I can tell, the biggest part that matters is whatever is between the window casing and the rest of the wall structure, and that is limited by the thickness of the window.

note that I don't do any of this professionally, so this is just how I would believe it to work from the theory side of it.

Posted By pacificstart on 27 Feb 2016 09:15 PM
Sailawayrb - I am indeed overly impressed with commercial bucks.

Here is why
1 Less work on building the buck out of lumber
2 No thermal bridges
3 No code compliance issues
4 No wood in the structure that can rot, etc (I love wood where it makes sense but not in the building structure).
5 No worries about replacing the wood in the long term

Plus: the Logix buck takes screws on all the three sides.

Here is a drawing on the possible attachments with the Logix buck.
https://drive.google.com/file/d/0B6cwnkZ3GHaaRzBncGJvbUtUSm8/view?usp=sharing

After spending some time drawing this I thought of a further improvement - cut off the exterior rib of the buck at an angle and insert flashing before the pour.
https://drive.google.com/file/d/0B6cwnkZ3GHaaOGwxVG1fMnhEbkk/view?usp=sharing

Pacificstart, I do believe you are way overthinking all this. Look at how I did my window bucks. I really think commercial bucks would have been more work. There is no thermal bridge issue, nor code compliance issue. Properly installed wood won't rot, at least not in your lifetime even if you're only 20 now and live to be 100! But then, IIRC there was only one commercial buck available in 2008 when I built my house.

I put the windows on the outer surface using the factory attached nailing flanges with caulking between the flange and foam on top and sides, fastened with 4" screws. I put flashing on the top side, the upper edge of which was embedded into the foam. On the sides I used 8" wide peel and stick flashing tape. The bottom flange is unsealed to permit any moisture that may happen to get in there to drain down. The window frame is about 1/2" smaller than the buck opening all around, with the gap being sealed with window foam. The sill seal on the bucks is to keep concrete from coming into direct contact with the wood. This prevents condensation from forming between the wood and concrete.

I think you are asking for headaches in planning to fit the windows tight into the bucks. Have you reviewed window manufacturers' installation instructions? If not, you need to do so. Even mounting them midway Andersen instructs you to use clips of some sort. The window frame is not nailed or screwed to the buck. By putting the windows on the outer surface of the wall I avoided needing sills.

BTW, I used BuildBlock forms. A couple of advantages over Logix. They are fully reversible, straight and corners, and the webs are spaced 6" O.C. horizontally.

And here is how it's done with Fox Bucks and Blocks!

Thanks for the pictures. I must admit that I am over thinking this. I am planning for tilt and turn windows opening to the inside. If you are wondering why I am opting for tilt and turn is because I need to install rolling shutters on the outside. So I can't use a nail flange. The windows will be attached with clips or screwed in through the frame. I initially thought of using a stucco finish so here is where the Fox buck would have an advantage.

Logix are a great block to use.... but, we prefer AMVIC. They are "unisex". They are a slightly denser block also. Fox blocks are loose formed, cheaper made. Nudura are nice for shipping since they are collapsible...

Realistically you can use any buck for an 11 1/4" block. I prefer wood like others have said, but it will depend upon the application. Your still going to need to reinforce it for the pour. Doors should always be wood or steel for rigidity. Windows can be wood or newer buck materials as the use is more vertical then horizontal forces. Interesting how it the thread started on blocks and ended up on bucks....We prefer Nudura's and Fox Blocks, we didn't really like the non reversible design of Logix years ago when I installed it. It works, just have to be more careful on your waste or start gluing...