reinstalling jalousie windows

[Patricia D.]

I have refurbished and reinstalled the windows on my Ventura but feel that I would like to put low expanding foam in the 1/4-1/2 gap around the windows inside the trailer as I have done in the house. Good or bad idea?
Is this the correct product for trailer use?

[John in Michigan]

Patricia, it depends on what the gap looks like. Can you post some pictures? Generally the windows are made watertight using butyl tape.

[Patricia D.]

I did use butyl tape on the outside and the windows are well sealed. There have been several rainstorms since then with no leaking inside the trailer.
You might be able to see, in the pics, a gap between the trailer frame and the aluminum window frame on the inside of the trailer.
Being from Michigan, you will probably understand the urge to insulate to stop drafts. That is what my question was referring to. Is it a good or bad idea to put some foam in the gap for insulation sake?

[John in Michigan]

OK I see what you mean. Sure makes sense fill the gap with low expanding foam. Another option might be polyurethane (or rubber) weatherstripping.

[k corbin]

The spray foams can create a rather sticky mess and they will overfill so you also have that to clean up after it cures. But there is a quick and easy alternative for filling in that gap that might work for you if your gap is not extremely narrow. That alternative insulation is closed cell, foam "backer rod". It is typically used to fill in overly wide gaps you want to apply caulk over. Close cell foam is a good insulator and it does not absorb moisture. It comes in 1/4" width on up to 1-1/4" width from some sources. Most stores tend to stock the 1/4" and 1/2" versions. Measure your gap and buy something just a little wider. They sell it in 1/8" increments in size. You want it to be somewhat compressed into the crack but not be so tight that you are fighting to get it pushed in.

You can purchase it from places such as Home Depot and Lowes. I believe the place I have seen it stocked in the past on trips to those stores is in the area where they sell weather stripping. You local hardware store might also have it, mine does.

The appearance of the product in this link when I look at it in person at my local Do-it-Best store is a lighter gray than it appears to be on the link I posted. Instead it is much more in color like the alternative image of the product that I have shown below that link. The price of the product is affordable and it is basically a no mess solution (unless you choose to caulk over it). It will have a better R value than minimally expanding foam in addition to stopping the draft.
https://www.doitbest.com/products/770396

[Buggeee]

Originally Posted by k corbin

The spray foams can create a rather sticky mess and they will overfill so you also have that to clean up after it cures. But there is a quick and easy alternative for filling in that gap that might work for you if your gap is not extremely narrow. That alternative insulation is closed cell, foam "backer rod". It is typically used to fill in overly wide gaps you want to apply caulk over. Close cell foam is a good insulator and it does not absorb moisture.

This is a very good and imprtant comment for two reasons. First, because the spray foam expands and expands and expands, usually beyond what you expect, and for a longer period of time than you would expect. Hours later you might still find a bloom of it had blossomed out of somewhere and it is hard to clean up. Needs acetone when wet and a razor knife and sandpaper when dry.

Second, spray foam is not waterproof. Over the counter spray foam is open cell, meaning the little bubbles inside it are all open to each other like a kitchen sponge. It soaks up and holds water for a long time. In contrast, closed cell products like closed cell backer rod have bubbles that are all closed from each other, like little balloons. They do not take water in. Closed cell foam is used in the hull of boats for that reason. Closed cell foam comes in a two part mix and then you pour it into the cavity to expand.

By the way, although not for window gaps like we are talking about here, if anyone knows of a spray closed cell foam product I would have a thousand uses for it but have never been able to find a closed cell foam other than a mix and pour.

[Patricia D.]

Thank you to both of you. The last thing I want is something that will hold moisture behind the wall covering. I will definitely get some backer rod. I have actually used it years ago in a house but had forgotten about it. Thanks for the reminder Karin.