Over or under t1-11

[Hunt Stoddard]

May seem like a dumb question, but if you build using t1-ll as both your exterior wall sheathing and also your siding. (which I believe is still code, at least it is on CA), should you install vinyl windows over or under the t1-l1? These will not get a lot of direct rain, so a bead of good caulk under the lip should make them waterproof.

[Tink]

If you are using the thicker T1-11 siding for both shear and siding, I would go with windows against framing with proper flashing. Cut siding panels to within a quarter inch of nail flange and install, following shear nail pattern all the way from sill to top plate. "Backfill" flange seam with good elastomeric caulking (Sikaflex) and cover with window trim
Water has an amazing way of finding its way in to start rot, especially around windows, so nailing windows over siding increases the chances of damage, in my experience. I also put a slight "slope cut" along the top of the top trim, so water can not puddle against the siding, but run off and down the window away from the siding. Others use metal flashing, but that gets tricky when using panel siding.

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[Hunt Stoddard]

Thanks. In a way it just seems more natural to put them over the t111 but I suppose you're right. I would be happy installing them outside the siding except for that top edge, which will catch water coming off the siding, probably even if I caulk the hell out of it.

[ericlp]

Always under. I put tar paper flashing around the entire framed window hole, and caulk the crap out of it along the window frame and along the t1-ll to cover the nail flange... Then, put on the window trim prim/caluk and 2-3 coats of bear outdoor over that.

Screw the trim boards on, also use liquid nails. keeps rain and bugs out! best to have 4' over hangs! Do what you can to keep the rain off the windows.

[EightFingers]

What happens if you have to replace a window? Say the style changed or the manufacturer went out of business.

[Hunt Stoddard]

quote:

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Originally posted by EightFingers

What happens if you have to replace a window? Say the style changed or the manufacturer went out of business.

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I think the normal procedure is to cut a little margin around the window thru the siding, not take all the siding off. Granted that kind of negates the value of overlapping the window with the siding. I guess this is where super duper caulk comes into play. I personally like polyurethane. You can lessen the pain by screwing in the window, not nailing it like you see a lot on Youtube.

One other thing I should note about not installing the window over the siding is that the depth of the window remains too much on the outside, even after you have a 1x trim piece the window is still sticking out about 1/2 to 3/4 inch. It kind of looks bad.

[bluesboy]

vinyl windows are designed to be installed under the siding.

[ericlp]

quote:

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Originally posted by EightFingers

What happens if you have to replace a window? Say the style changed or the manufacturer went out of business.

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My window install? I over do it, so, I'd probably just cut around the flange, get a new window cut off the flange and screw it in.

Probably sell the house before that ever happened.

[Hunt Stoddard]

Since I'm beyond this point, here is what I did, if anyone is interested.

Collecting everything I learned here and on youtube, the window directions, etc.:

Framed walls (of course)

Put tyvek on studs, stapled with probably too small staples

Hoped for no wind storm

Did the usual cut out big X in windows, pulled extra tyvek inside and stapled on studs (Edit: except top edge, which I cut even with top rough opening)

Got peel and stick weatherproof flashing from HD, (which they are out of but I found a couple rolls that had fallen down behind)

Taped window sill framing and up jack studs 6 inches

Cut tyvek diagonally up from upper outside corners so I could peel it back

Screwed in windows, flopped top tyvek edge over top window lip

Taped down edges of window

Taped across top of window under tyvek but over window lip

Taped over diagonal top cuts

Put t1 11 on studs, over window lips as accurately as I could, nailed with 2 inch galv ring shank.

I'll probably just put 1x trim over all that and call it quits.

If I did anything major wrong, I don't want to know about it.

(No, not really, hit me with your best shot)