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Window Install Questions


MiamiCuse's Avatar
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FL

04-18-13, 07:50 AM   #1  
Window Install Questions

I have a couple of window installation questions. In this case it's an aluminum window.

I have included a sketch to explain my questions below.

(1) I have seen a bunch of youtube videos and also hired window pros to install windows before. What's confusing me is most of the videos I saw, they do a water proofing all the way around the window opening with felt plastic or whatever, folding over to the outside surface of the exterior wall. However in South Florida, I have NEVER seen any window guys do any sort of paper waterproofing. Most of the time it's just buttering some caulk and sealant. Why is this? Is it because most homes down here are masonry walls and the stucco layer over the edges effectively waterproofs it?



(2) When installing an aluminum window, install instructions said to apply a bead of silicon all the way around the underside of the flange (point A in my sketch), and put the window up. That seals it from the inside. After it's all secured and screwed in, then another bead of sealant all the way around between the edge of the flange and concrete on the outside. Sounds good. However, I have seen people down here removed windows on a few projects, and I have never seen any caulk or sealant on the underside of flanges. Usually the cut the outside sealant with a blade, then unscrews the edges, and the window comes out, never any window got "stubborn" with any sealant on the inside of the flanges. So is that inside flange silicon really necessary?

(3) On a concrete wall, do you set your strips of window buck tight to the window frame by shimming between the buck and the concrete face? Or do you attach the buck to the concrete face, then shim between the window frame and the buck? Which is the right way?

(4) Since there is a "lip" around the window frame (point B), once I pushed the window in there is still a little bit of space between the window's metal edge and the buck. When I try to screw the window in through point D, the screw will "pull" the edge towards the buck. Is this OK? I was thinking inserting another piece of 1/8" shim under the screw hole but the lip is in the way I can't slide it in there.

Thanks for any advice!

 
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XSleeper's Avatar
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04-18-13, 08:54 PM   #2  
(1) don't really know what you're talking about there. Wood framed walls and walls that will get a stucco overlay are one thing. masonry walls are another. they aren't treated remotely the same, so I'm not sure how to answer your question. Windows in masonry openings commonly get caulked in on the exterior, and that's the only weather barrier.

(2) ummm, well if the mfg says to caulk the fin, you should caulk the fin. A lot don't do it because it's probably a shortcut they think they can take (especially when they are going to caulk the outside perimeter after the install is complete) and the bottom line is that if the window doesn't leak, or isn't drafty, then the job is "adequate" in their opinion. It's hard logic to argue with because I know a LOT of guys who don't caulk behind the fins. If you're a certified window installer, yeah you better be caulking behind those nailing fins. It's a secondary defense against water, especially if there is no WRB or flashing tape being used. If the window installation is a "flush fin" installation where the sealant behind the fin is the ONLY sealant being done on the outside, then obviously it's imperative that it be caulked.

(3) buck tight to concrete, then shim the window. The buck should also be sealed to the cement with a sealant. Silicone is not my first choice for any type of window sealing other than glass, or a commercial job, and then it's the $13/tube variety, not the $3 GE stuff.

(4) looks to me like if you added a piece of wood onto the buck so that it butted up against the lip (point B) it would no longer move. The inside corner that would create could then be caulked again with sealant. You obviously can't torque those screws down or it will distort the frame.

Biggest concern I would have is an aluminum window being in contact with pressure treated ACQ. Those 2 things don't play nice, which is the main reason you'd want a barrier between the two. Maybe that is what you were getting at with question #1?

 
MiamiCuse's Avatar
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04-19-13, 08:53 AM   #3  
XSleeper. Thanks.

(3) Care to recommend a sealant to use to seal the buck to the cement? Right now the way I did it, I set the block and drilled the Tapcon holes. Then I pulled the buck off, cleaned up the cement dust, then applied a thick bead of "Loctite PL Premium Polyurethane Construction Adhesive" to the underside center of the buck, then drove the Tapcon screws back in, tight. I didn't do too much of it so it didn't squeeze out the sides. I can supplement the outside joint with another sealant if you have one you'd recommend.

(4) If I do add another piece of wood to the buck it will fill in the "channel" nicely, however, I can't push the window in anymore because of the "lip" around the inside of the window frame. That lip is also preventing me from shimming between the buck and the frame near the screw holes.

As for aluminum and ACQ lumber I heard about that but no, in this case it wasn't what I was thinking. I am using all ACQ rated lumber, but I thought the issue with aluminum @ ACQ lumber is only a concern if the aluminum is raw? In my case the window is of bronze color I don't know if it's painted or powder coated that's OK right?

 
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04-21-13, 07:06 PM   #4  
I don't trust even painted aluminum against ACQ, but I can't recall reading anything definite on "painted" aluminum. I would trust powder coat farther than painted aluminum.

As for the sealant, 1st choice would be NP1, which is available in several colors, either to match the window or the cement (limestone or gray) You might have a hard time locating it in your area, it's pretty common here. Maybe Vulkem would be another good choice.

Since I can't see the window or ready the installation instructions I don't totally understand why you are adding jamb screws... doesn't this window have a nailing fin? Sometimes installation instructions cover various types of installs... I wonder if you might be going overboard with screws or something that aren't really needed.

 
MiamiCuse's Avatar
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04-23-13, 05:43 PM   #5  
No there is no nail fin.

Here are the install instructions.



as I stated earlier, it's difficult to fit the window though the buck because the lip on the inside of the window frame. Now if I shave 1/8" off the buck the window will fit through fine, but then I end up with some space between the buck and the edge of the frame once the inside lip clears. Not sure if I am explaining this clearly, but the diagram illustrates my point.



Now if I need to put in the jamb screws, I need to shim between the buck and the frame. But the lip is in the way again. If I need to push shims in there I would have to pry the lip back, like this.



Here is a picture of the actual window. If I jam some shims in there I would end up bending back the lip.



Last edited by MiamiCuse; 04-23-13 at 06:02 PM.
 
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