Check my plan for window installation

[TravelingLight]

I'm wrapping my 12x20 shed with tyvek this weekend. And I'm ready to put in the two windows (basic, single hung). I've watched different videos and read different stuff, so I want to make sure my plan is sound and complies with 2015 IRC.

My window rough ins are 24 x 36. The windows I am installing are 23.5 x 35.5.

First, I plan to wrap with tyvek, and cut out the wrap covering the rough in opening. On the bottom and sides of the window opening, I plan to fold the tyvek into the rough in opening and secure. The flap of wrap at the top of the frame will go over the window flange.

Question 1: If I am doing the tyvek this way, do I still need to also use window flashing tape?

Next, I'll put a bead of sealant (exterior, window grade stuff) around the flange so it seals between the flange and the OSB sheathing. Insert the window and check for square/level.

Question 2: Since my window is a half inch less than my rough in opening, I'll need to shim. Am I correct that I will first shim the bottom of the window to lessen the gap up top and essentially get it centered in the opening? Then shim the sides to get it centered there as well.

Then, I'll secure the window to the opening with fasteners through the flange. Then I will put the top flap of tyvek wrap over the top flange.

Questions 3: At this point I should put flashing tape around all four sides of the window, correct?

Finally, I'll install my 1x4 trim boards around the frame, caulk around that, and use spray foam on the inside of the shed to seal/fill in space around the window.

Question 4: Should I do a 1/8" gap around the window between the window and the trim pieces to allow for movement?

Anything else I'm missing or anything I should do differently? Thanks.

 

[yeldogt]

Installation depends on the window -- some have flanges. It's also a shed -- so water intrusion .. insulation is different.

What type of window -- what does the instruction sheet say?

 

[TravelingLight]

Installation depends on the window -- some have flanges. It's also a shed -- so water intrusion .. insulation is different.

What type of window -- what does the instruction sheet say?

Great points. I haven't picked up the windows yet, so I don't have the instructions. But I do know that they DO have flanges. No insulation in the shed, just open studs. Thanks.

 

[zak77]

Since it's just a shed you can forgo the foam around the window. Make sure the sill plate is level and just set the window right on that, double check for being level and plumb and center side to side, nail flange. I'd probably skip the flashing tape and just use a good caulking on the flange prior to install. But without knowing all the details, that's usually better than how most are installed.

 

[Bert_]

The only thing I can think to add is a drip edge on the head casing.

My opinion is to forget the caulk. Proper flashing always directs the water to outside, eliminating the need for any caulk or sealant. Caulking will last years. Flashing will last decades or even centuries.

 

[yeldogt]

Agree with Bert ..... caulk is so overused. Tape as well .... proper flashing.

Buy -- The OP is doing a shed. So -- less is more.

 

[TravelingLight]

The only thing I can think to add is a drip edge on the head casing.

My opinion is to forget the caulk. Proper flashing always directs the water to outside, eliminating the need for any caulk or sealant. Caulking will last years. Flashing will last decades or even centuries.

Are you talking about something like this?

 

[QwikKotaTx]

That rough opening is a little tight, does not leave much margin of error. The one I put in last weekend was 3/8" Gap on each side and with some twisting of existing framing the window would not move left to right once installed. I had plenty of room up and down though. As far as level goes, focus on your sill plate since the shims for height go there. The header being perfectly level does not matter as much.

I did the tar paper adhesive flashing tape on my garage just to be safe.

Sent from my VS987 using Tapatalk

 

[Falcon67]

And I did the opposite - tar paper around the window openings, windows mounted, then the siding over that. Trim over the siding. Caulk top and sides of trim. No leaks.

 

[19D2P]

I would not flash the bottom over the flange. It will do nothing good for you, but will prevent any water that did get in from getting out. Same with caulk, only on top and sides.

I’d make a bottom sill out of flashing before the window goes in.

 

[Ben W]

If you're overhang is as large as the pic that 'QuikKota' posted then the answers can be a whole lot different than if you only have a couple inch overhang ...

I'd fold the Tyvex in first on all 4 sides - if you're going to tape all 4 sides in the end anyways, then you'd be trapping any droplets inside the Tyvex at the top either way. So fold all 4 sides in and staple so it's tight.
I probably wouldn't bother caulking - messy and you're going to tape in the end.
Set the window in on shims - (1/2" greater rough opening is what you want)
The shims aren't there to 'center the window', they're there to level and plumb your potentially out of plumb RO.
Fasten through the nailing flange
Tape all 4 sides starting at the bottom.
Foam if you want to.
Don't worry about leaving a gap between your trim and the window.
Don't worry about Z flashing, etc.

If you don't have decent overhangs, then the sequence/flashing/etc. is a little more important. Think shingles - you work from the bottom up with everything above overlapping what's below.