ICF and Windows
Last Post 22 Oct 2008 11:47 AM by Manfred. 22 Replies.
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Boontucky-girlUser is Offline
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15 Aug 2008 08:39 AM
It just dawned on my that my ICF walls are 12 inches wide, and the widest jamb I can get is 9" for my windows. We're going with stucco on the ICF, and I was wondering how to install the windows recessed so they won't like. Someone told me to not order the jambs, but I really didn't understand why?
How can I install the windows so they won't leak?

And the window bucks are recessed into the concrete. Do I make the opening just the rough opening required for the window, or do I have to make it larger to finish the sill?

Any help will be appreaciated.


Chris JohnsonUser is Offline
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15 Aug 2008 12:51 PM
enlarge the opening

i.e. window 36x60

finished R.O. is 39 1/2 x 63 1/2 plus the thickness of any sill you are planning to install

This allows a 2x to be run around the buck, install the window and have something to nail to fins to, leaves a little gap for adjustment and insulation.

when done, laminate some 1" foam from the exterior to the face of the window fin.

Flashing is extremely important, use galvanized metal pans if the budget allows it, they are the best

I have always found it easier to rip and install my own jambs on ICF walls since no ones jamb extension fits the way it needs to and you normally have to add to it anyways.



Chris Johnson - Pro ICF<br>North of 49
Gene DavisUser is Offline
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17 Aug 2008 08:16 PM
Can you read the note and see the detail on the image?  This shows a way to detail an ICF-wall opening to receive a conventional wood-inside and clad-outside (read:  Andersen, et al) window outfitted with the minimal "drywall return" jamb (i.e., about 3-3/4" wallframe depth, total).

The outside is stucco or EIFS, and the window gets a surround exterior casing of 1" EPS foam material, that gets plastered the same as the walls, and at the same time as the walls.

Inside, you get the "church window in thick wall" effect with 45-degree laybacks on sides, top, and even bottom if you want.

It is all in the details.

Attachment: ICF window framing.jpg

Gene DavisUser is Offline
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17 Aug 2008 08:36 PM
Here is some more info on how to do it.

In the first pic, the ICF opening is shown after the opening has its "for the pour only" bucks and bracing removed.  What is left is the continuous side and top embedded PT wood parts, and the two partials at the sill.

Those embedded parts will have been ripped to fit to the depth of the concrete core of the ICF blocks, and will have been studded with galvanized lagscrews head end into the concrete, so as to better tie the embedded wood parts to the concrete core.

The next two pics show the 10-piece wood assembly that goes into the opening, which makes up your window structural surround, and your beveled-edge framing that makes angled drywall returns possible.

The outside gets sheeted in EPS for ease of exterior finish, and the spaces between the window surround rough frame and the beveled outside frame parts gets foamed with something like Tiger Foam, an easy way to do jobsite urethane cavity fills when you need to do more than just foam cracks around windows and doors.

Attachment: ICF window framing 1.jpg
Attachment: ICF window framing 2.jpg
Attachment: ICF window framing 3.jpg

robinncUser is Offline
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18 Aug 2008 12:53 AM
This may be a dumb question, but what if you wanted to have a brick exterior?


KlorinthUser is Offline
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18 Aug 2008 04:14 AM
Very Nice descriptions... I now wish that I had seen the "church window in thick wall" while still in the design stages. That would have been perfect. I have seen that done with straw bale construction but not with the ICFs'.

The use of sray foam and boards makes perfect sense. Would you do the same 45' angle on the top of the window? I believe this is what was traditionally done in the stone work of churchs and such. I can't quite tell from the picture.

I think I need to look at my windows when they arrive and see what I can do with them. You have mede me think a little more.


Boontucky-girlUser is Offline
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18 Aug 2008 09:04 AM
Thank you so much for that detail. That looks great! So let me rephrase to see if I understand this correctly.
I order my windows with the standard jambs on them for 2x4 construction. I then make the r.o. on the ICF much bigger than the window. How wide? As wide as it takes to meet the drywall at a 45º angle?.
How do you do the top?
Also, could I have the window recessed in from the outside, or is that not a good idea?

Thanks!


Gene DavisUser is Offline
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18 Aug 2008 09:41 AM
This detail seeks to eliminate, as builders have done in stone buildings for over 6,000 years, the "tunnel" effect of a light through the wall, and seeks to make the opening and wall seem lighter, thinner, less confining.

Watching a Meryl Streep movie on DVD last night, the setting being rural Ireland in 1935, I noticed the windows of the stone farmhouse for the movie setting had this detail.

Thus, if you simply recess the window into the inside wall plane, but do not taper the opening shaft, you have not accomplished what is needed.

My detail has the tapers at 45 degrees, across the top, and down each side.  Windows are specified to be made with "factory installed drywall jamb extensions," and not the deeper ones used for 2x4 wall construction.  Those are typically called out as "4-9/16" jambs."  With the little drywall return things, your total jamb depth is more like 3-5/8".

The design needs to be worked out on paper or with CAD, once the window is specified and it is confirmed that the supplier can give you what you need.  Depending on the window company, this little jamb extension (a tongued section of softwood about 3/4 x 3/4 in section) may or may not be available.  If it is not available, the windows can be ordered without any extensions, and the small surround can be readily done at the site before or after installation.  A good trim carpenter with graphic skills, or an architect, can do this for you, if you cannot.  I can do it for you if you want.

Andersen has this detail available for their windows, the "factory" drywall return, but only if you buy them prefinished white on the insides.  Go figure.  Search for it in the downloadable window section views available at their website.  I am looking right at the detail, shown on p. 17 of Andersen's 260-page publication titled 2007 Product Guide for Professionals.  It is called the drywall return bead, is prefinished white on its exposed face, and can be ordered either factory-applied to units ordered with prefinished white interiors, or ordered as "non-applied lineals."

If I was doing this in stain-grade, I would get a small hand sample of the bead through Andersen, then either shop-make the parts myself, or have them made by a local shop with a molding setup.

The reason for the CAD or on-paper workout of design and dimensions is because ICF walls vary in total thickness from manufacturer to manufacturer, and window companies do different things with frame details.  The model I did is for the AMVIC 6" core block, which has an overall T of 11 inches.  Change that, and you change the spread between "inner" and "outer" wood surrounds with the beveled edges.

In my detail, the 1-1/2" wood subsill, shown in my pictures, gets capped by a finished trim sill with apron underneath.  The drywall returns come onto the sloped edges of the inside wood surround at three sides, and then the window is trimmed with small casings at the three drywall sides.

The picture below shows the opening from the inside, with the window unit not shown.  You can see the 5/4 bullnosed finished sill part which has "horns" at its L and R ends to project out past the opening sides.  The finished apron trim part will go up under that sill and cover the subsill.  The drywall returns are in place at the three sides, but the wall drywall is not shown on yet.  This is out of sequence, rock-wise, but the pic is so you can understand the look and the parts.

Attachment: ICF window framing 4.jpg

Boontucky-girlUser is Offline
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18 Aug 2008 12:30 PM
Ok, that makes sense. Here's a little detail I drew using paint and the Andersend detail for the vertical view.
I was thinking that I'd like to have the window recessed in a little bit from the outside, and do the sloped recessed like yours on the inside. What do you think about this picture? I'm still not sure where the flashing would go or what I need to do to make sure it's watertight and leakproof.

Thanks

Attachment: Window Vert Detail ICF.JPG

Boontucky-girlUser is Offline
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18 Aug 2008 12:39 PM
The drawing is not to scale, but I will try to draw it out on paper and see what the dimensions come out.
My wall is 12.25", with 2.25" thick foam and 7.75" concrete core.


Boontucky-girlUser is Offline
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18 Aug 2008 12:41 PM
Here's the horizontal detail. Thank you so much for such a great idea!



Attachment: Window Hor Detail ICF.JPG

Boontucky-girlUser is Offline
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09 Sep 2008 09:01 AM
Gene,

How do you flash around the windows?


Gene DavisUser is Offline
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09 Sep 2008 10:17 AM
Go here http://www.stocorp.com/allweb.nsf/deteifs and download and print all the details for FLANGED WINDOWS.


JamesrUser is Offline
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09 Sep 2008 06:51 PM
Why are you limited to 9" on your windows?  What manufacturer are you using?  Most manufacturers can double stack the jamb extension and reach the 12" wall.


woulfccUser is Offline
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09 Sep 2008 07:15 PM

 I see what your looking for and I hope to show you what can be done with an icf buck and get the wood out.



Changing How the World BUILDS!<br>Green , Done , Easy<br>Woulf c.c. of Wisconsin
Boontucky-girlUser is Offline
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10 Sep 2008 09:08 AM
Thanks Gene. Jamessr, the limiting factor is cost. I've priced the windows with the extension jambs and it does change the numbers enough that I can't go with the bigger jambs. Also, I do want the windows recessed.

Woullf, thanks. I look forward to the info.


Buddy NewberryUser is Offline
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07 Oct 2008 01:55 PM
Woulf is right about the advantages of EPS bucks.

ICF's construction is all about thermal dynamics, and ensuring that the thermal performance of your ICF envelope is performing to its maximum potential. The way ICF's work is through a term called "The ICF EFFECT", insulated thermal mass and Air Infiltration Control. This term refers to the dispersion of the earth's energy throughout the ICF structure. Four feet below our feet the earth's temperature is 55 degrees. In considering the fact that concrete is a thermal conductor this temperature of 55 degrees then radiates throughout the footings and continues up within the concrete core of the ICF wallsystem. Concrete does not have an R-value, but when it is super insulated between two panels of EPS type 2 a term called "R-Performance" comes into play. The constant temperature of this concrete core repels both the inside and outside temperatures from travelling through your ICF structure resulting in award winning R Performance. The R-value of a home using conventional construction methods is ensured through the contractor's meticulous attention to the envelope tightness and performance, he may be using R-20 insulation but it is up to his expertise to ensure R-20 perfomance. In ICF construction the performance of the envelope is ensured by the product not the contractor.
I went on this tangent to illustrate the importance of having an insulated bucking system. If your RSO's are not insulated, the thermal dynamics of your ICF structure have been compromised. PT wood and other non-insulating bucking systems create a thermal bridge across the system, and at a point where outside temperatures are most likely to penetrate; at your windows and doors. 
There are many different products of insulating bucks on the market and most of them perform on the same level. I would recommend IntegraSpec's bucking system simply because it has a furring strip within it to make installation of windows and jamb extensions much easier. As well, in noticing some of the pictures attached above in this forum, IntegraSpec also has a new patented insulating bucking system that has a 30 degree bevel on it giving you the Church Window look while also insulating your RSO's. Finally, insulated bucks are oftern cheaper per lineal foot than PT and easier to install in most cases. 

Buddy Newberry,

Attachment: Santa FE Win Ass1.jpg

Boontucky-girlUser is Offline
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17 Oct 2008 09:46 AM
Wow, that's an impressive system. Too late for me. I've already cut and placed my bucks. I used the design that Gene Davis provided, except that I don't have the notch on the outer face. Instead, the sheathing and foam cover the window studs too, and the window will be installed on top of the foam. I wanted to minimize thermal bridging as much as I could.

Boontucky


FarmboyUser is Offline
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19 Oct 2008 12:12 PM
I would be interested in seeing some photos of your bucking if available. Thx Dave


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21 Oct 2008 05:05 PM
Here's some pictures that I have. Basically, our ICF wall is 11" thick, and we built the outer frame to 9 1/2 inches wide, and added half inch of sheathing and 1" of blueboard on the exterior. We covered the whole window and when it is time to install the windows, we will cut the sheathing and foam along the interior of the inside frame and the window flanges will be installed on top of the foam.



Attachment: Window2.JPG
Attachment: Window.JPG

FarmboyUser is Offline
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21 Oct 2008 09:07 PM
Neat idea about the blueboard and you can always recycle the part you cut out later. I see you used a moisture barrier between the non-PT window buck and concrete. Thanks for posting the photos. I'm thinkin we'll try this on a couple of windows in our upcoming home. Cheers, Dave


Boontucky-girlUser is Offline
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22 Oct 2008 09:11 AM
The windows were a lot of work. A lot more than we wanted, but I think the windows will look very nice once it is all finished.

The design that Gene Davis gave me here on this thread is a little different in that his particular design uses two window bucks, basically. One that is recessed in the ICF concrete gap, then another one to do the window design. We decided that the window buck used enough wood that we couldn't justify doing two bucks, so I think that's why we went with the solid wood on the bottom to help keep that frame sturdy. And we cut holes in it for the concrete.
But I think two 2x4 would accomplish the same thing, save labor, and we could even place two smaller ones on each end for more support if we needed it. I saw that on some other thread, but it was too late for us. You can see a quick drawing I did to show the two 2x4 idea.

We went with non-PT wood because I work with PT wood a lot and the new treatments that replaced CCA make that wood twist and warp like crazy and we didn't want that on our windows, so we bought heat treated lumber in Doug Fir, since it isn't as susceptible to crazy expansion when wet like Pine, and were very careful to store it right while we worked so that the lumber stayed flat. But next time we will use a peel and stick waterproofing instead of the one we brushed on. This was messy, and smelly, and very time consuming.

We did use pressure treated wood for the bottom of the sliding door buck, but since we had to rip it to size, we did put waterproofing on the edges that we cut. Any time you cut into treated wood you compromise that treatment and basically nullify what the treatment is supposed to do. When I get complaints that treated wood is rotting, I always ask if they cut it, bored holes, or anything like that, and if so if they applied some wood treatment or waterproofing. Because any cut or hole bypasses the treated portion opening up non-treated wood, since the treatment only penetrates so far. So keep that in mind if you decide to go with PT wood. Also, I don't have inspections on my house so I got away with getting CCA treated wood for wood foundation use. Though technically it is being used in the foundation. :)

Hope that helps!




Attachment: window.JPG

ManfredUser is Offline
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22 Oct 2008 11:47 AM
Boontucky, very nice display of window bucks. I am always looking for new ideas. I do prefer the concrete solution for bucks simply because wood is not a stable material. If untreated you have to cover it with whatever, so it does not come into contact with the concrete, if PT it will have chemicals in it, which, in the end, carcinogenic or not, will not be good for you. I like your overall approach to the woodbuck problem. Well done.


Manfred Knobel<br>Moss Pointe Builders, Inc.


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