Window Installation – Spray Foam Shrinkage Surprise!

Don’t be fooled by my previous post. I don’t know everything. I’m just some guy who teaches himself how to do things on the Internet. And I had a non-standard situation to work with here. With Window Number 1, we had (and spoiler: resoved) a catastrophe. But only briefly.

First off, I spray foamed the window into place. There’s a different kind of foam for windows and doors that expands less and remains flexible. Good. Happy. Done. Nice window. We go to bed.

Sunday morning we get back from breakfast and I’m looking straight at the window we installed Saturday and I can see sunlight between the sash and the jambs! They were straight the day before, but now the jambs have bowed in toward the brick. The large gap spray foam I used between the pressure treated nailers and brick shrank after we installed the window.

So. First I screamed some things that don’t meet the linguistic standards of this blog. Then I stood there for a few seconds. Then I bolted out and pooped. Then I pulled myself together, grabbed a knife from the kitchen, unscrewed all the nailing fins, and cut the spray foam between the window and the nailers. Then I held the 4-foot level up to the window. Yep, bowed. And pretty stuck, too, but I was able to drive shims in with a hammer and straighten it out again. Big, big phew!

Monday night they were a little bowed again, so this time I shimmed between the nailers and the brick. First I gouged out a rectangle of spray foam right by the meeting rails with a screwdriver.

Then I was going to cut wedges of pressure treated wood to fit perfectly into these gaps, but I wouldn’t be able to get them in, so instead I put in marine grade plywood to fill most of the gap, and then drove in shims.

And the second window is in the opening, but just barely. No spray foam, no shims, the brick mold is wedged in but not attached, and there are only enough screws to assure that the window won’t fall out. Finishing it will be a 2 person job: pull off the brick mold, make sure the window is square, plumb, and level, shim it, screw it in place correctly, screw in the brick mold, and spray foam it. For now, I took care of the most urgent part: I bent down the nailing fins and reinstalled the cheap plastic mini-blinds.

So I learned my lesson. I framed out the downstairs windows with little blocks at the meeting rails, and only did the outer layer of spray foam. The sides puffed up so much that I could barely get the window in, but they’ve already begun to pull back away from it, so it will all be fine once it’s done shrinking. We could barely get this window into the opening just one day ago. Now the gap is all the way back.

And I had one new problem to deal with here: the sides of the brick openings are like a half inch out of square! It looks like the original windows were installed that way and then the replacements were inserted into the crooked openings, which (partly) explains why they were so bad. The new windows are unforgiving and I got them dead square, but the flat frame reveals look a little funny.

But that’s par for the course in the Crooked House, right? With or without that weirdness, the Crooked House looks great now that it only has ugly windows in the basement. I think 4 windows was the perfect amount to figure out what I’m doing just in time to never do it again.