how to seal for window install if siding is flush with the rough opening?
hi folks, i hired a handyman to install new lapped siding on our non-complying outbuilding. after laying tarpaper, he installed the siding flush with the rough openings. i’m getting the impression this was a mistake.
we have windows without nailing fins and of course they can be screwed into place through the shims. the advice of the window seller was to paddle Henry Air-Bloc Liquid Flashing in the rough opening, then install a foam rod, held in place with a stop, around the edge of the top three sides and running to the back of the opening at the bottom. i’m comfortable with all that, but the LF instructions say to spread it around outside the opening — now impossible — and i don’t know what to do with the folded flaps of tarpaper.
what would you do in this situation?
Replies
I assume the windows you have include brick mold, which means they lap the edge of the opening. Any sealing you do can be wrapped around the corner of the siding, so long as it doesn't protrude beyond the brick mold.
You may, of course, need to install jamb extensions on the inside, if the window jambs are not deep enough, but that's relatively simple stuff.
What will the trim look like?
The siding can be cut back to allow room for the trim,and that will allow space for proper water proofing. Be careful not to cut the paper when trimming.
Flashing grove?
Do your windows have a small grove around the perimeter, barely 1/8 inch wide? This would be a place to insert aluminum trim coil. You may be able to caulk that in place and then use it as a nailing fin and flash to it with flexible flashing. Then use trim to hide the flexible flashing.
Seal all your trim end-cuts. Seal the end cuts of that siding. Also be careful about material compatibility between flashing material, caulk, and window material.
here's a photo of the window
hi folks, thanks for your thoughts. i don't know if this is "brick mold" or if the groove for trim coil is there. the nailing fin is present after all, but i've been cautioned not to nail it to the siding. i thought the reason not to cut away siding was that we'd cut the tarpaper as well. if some few cuts to the tarpaper are not fatal, then we can go that way. the trim will be several inches side, at least twice the width of the nailing fin.
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There's no compelling reason to not nail it to the (relatively smooth, solid wood) siding, then cover with trim, though of course you'll probably need jamb extensions on the inside. And you'll have to be slightly creative with the flashing and sealing.
Recent JLC article on this subject
I recently noticed an article in the Journal of Light Construction email update that handles a similar topic. I think it may have some ideas for you. THe link is below
http://www.jlconline.com/how-to/exteriors/flashing-recessed-windows_o?utm_source=newsletter&utm_content=Feature&utm_medium=email&utm_campaign=JLC_103016%20(1)&he=735cb38d11b5bda74d547a38d0b59b568dda0661
I also just noticed the picture you posted. Those fins that are bent back ARE nailing fins. They're meant to be folded out and nailed to the face of the sheathing. Often this style has a flexible/stretch connector at the corners. Yours does not. You can probably remedy this with flex flashing. Be carefull about material compatibility though.
Cut the siding back so that you can flash properly. Shortcuts always turn into longcuts. Dont forget a cap flashing.
What would I do?
1) Get nailing fins and install them on the window. 2) Tack the window into place, making sure it is level and plumb. 3) Using a piece of trim mark the outside of the trim all around the window. 3) remove the window. 4) Cut back the siding and prime cut edges. 5) Install the window and screw nailing fins to studs. Use scrap trim to perectly locate the window. 6) Run sealant tape all around the nailing fins starting at the bottom, with the side pieces overlapping the botton sealant strip and the top sealant strip overlapping both side pieces. 7 Insert Z-flashing below the siding, directly above the window. 8) Install trim 9) Run a bead of a high-grade caulk such as Lexel (excellent adhesion...glue-like..paintable) all around the siding/trim interface. 10) Paint
It is fine to use a circular saw for most of the cuts in the siding. If in doubt, screw scraps of 2x material to the siding to guide your saw and make perfectly straight cuts. Use the DeWalt oscillating saw (nothing short of awesome) to achieve perfectly square corner cuts. The whole operation is simple and straight-forward.
Now I'm gonna tell you sommat even better! Ler's suppose you are using standard, 2" wide brickmolding trim. When you back-cut the siding, cut it back 1.75" (not the full 2" width of brick or any other 5/4 molding of your choice). Run molding pieces through your table saw, creating a rabbet cut on the outside edge of each piece. The depth of the cut is proportionate to siding thickness+. The width is a tad more than 1/4"...say 3/8". This gives you a bit of wiggle room. Do this on the bottom and the side trim pieces, but not at the top piece (due to the Z-molding you have already installed. You're going to have to make tiny rabbet cuts at the outer edge of the top piece...don't panic, this becomes obvious as you work the trim.) If you don't use Z-flashing, the top trim piece gets the same rabbet cut as the other trim pieces. When you install the trim (for the sake of simpicity I shall assume you are using mitered corners), run a bead of Lexel caulk on the rabbet cut (previously primed). You should have a water-tight fit all around the window.
I'm NOT a fan of aluminum ("maintenance free") trim, but if you use it, you can lay it over the wood trim.
That's it! Simple. Sounds far more complex than it is. Every step is logical to the eye and the mind of reason. :) And don't forget to prime the trim front, back, edges and cuts!!
Mel (master craftsman with attitude :) froscarpentry.com
Hi there,
It appears that the builiding has no sheahing (pine boards or plywood across the studs). If this is the case, then the new siding is essentially the sheathing. This is not a mistake on the handyman's part if this is indeed the scenario. Windows with nailing fins, like your Integritys, are designed to be installed on top of the sheathing before the siding. You will have to be a little creative. For an outbuilding, I would install the new window following the manufacturer's instructions as if your siding was the sheathing. The only odd part will be flashing the head properly. This issue has been discussed a few different times on this forum usually in regards to vertical or sheet siding like T1-11. The best way is to place the head trim above the installed window, trace the top, then cut through the siding on that mark so you can slip a peice of 1 1/2" window cap flashing in. An easier method and maybe acceptable depending on your location, roof overhangs, planned sceduled maintenance etc. would be to make a beveled drip cap to sit on top of your window head trim that can be caulked to the siding. I would never do this on a home, but an outbuilding is another story. Good luck
Yeah, you have nailing fins, and the siding is the sheathing. So basically you install the window as you would on a sheathed-but-not-sided house, then install trim to cover the fins, with the only tricky point being the head flashing.
after considering all the posts and comments we invited here and in person, we decided to nail the fin to the siding. cutting siding away to mount against the frame would have set the windows too far inside the building, the windows are protected under a roofline, and we did not have the building wrap to duplicate the manufacturer's instructions in any case. the trim is being nicely caulked up except for the bottom edge. thanks all for your input on this difficult question.