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Replacing old jalousie window with vinyl Single Hung Window

Replacing old jalousie window with vinyl Single Hung Window

Old 12-14-15, 02:33 PM
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Replacing old jalousie window with vinyl Single Hung Window

I've decided to replace an old leaky (from air, that is) jalousie window with a vinyl single hung window. My preference is to remove the whole thing, frame and all, rather than use a retrofit style window (mainly because it would cut down on the glass area quite a bit). I have found a window (off the shelf) that should fit my rough opening. The exterior siding is wood (shiplap placed vertically). I understand how to get the old window out, no problem. The two things that are somewhat unclear to me at the moment are:

1) Flashing &/or sealing around the opening. Since I'll be removing only just enough siding to remove the old window, I won't be able to apply new flashing around the rough opening, like I would if I was building a new house. A couple of sources I've seen show just applying caulk on the back of the nailing fin before nailing in place. If this is an OK method, should the old flashing be removed (assuming it hasn't disintegrated) or left in place? If left in place, should I tape over any nail holes, etc?

2) I'd like to apply 1x3 or 1x4 wood trim around the outside of the window, once its installed, to cover over the nailing fin. Is it OK for the trim to just overhang the nailing fin, unsupported, while the outside edge of the trim is nailed in place? I feel somewhat uneasy about this. Like if the trim twists or shrinks, it may allow water in.

Is there some reliable online source that you guys trust for replacing a window like this? I've read a lot online and in books, and watched a lot of videos, but I get conflicting info sometimes, and I don't always know who to trust.

Thanks in advance.
Old 12-14-15, 06:02 PM
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There is no good way to give you instructions without being there. Basically your window will be smaller than your RO, once you remove your old window. So you need to resize the opening to fit your window. The new RO should be about 1" larger than the frame of your window. This will allow room for shims and insulation on each side. So you will add framing to the rough opening as needed to make that happen. Could be 2x4s or 1x4s, we can't say. You will likely also have to extend your sheathing to meet the edges of the new RO. We also can't possibly know what dimension lumber or plywood you will need to do that. The sheathing is the level on which you would place the nailing fin of the window.

On an install where you will not be replacing siding, you just do the best you can. Typically I will put a strip of window flashing tape across the bottom of the RO and wrap the bottom corners of the RO with it, so that the window is installed on top of the flashing tape on bottom. Then you can install the window, caulk the perimeter first, then push the nailing fin into the sealant. Once it's in, I would normally cover the sides and top with window flashing tape, attempting to fully cover both the nailing fin and the exposed sheathing.

Personally, I want the trim around a window to be symmetrical. So after the window is installed, I will measure where the trim will be the widest, and cut all the siding back so that the trim can all be the same width. Looks better, IMO. You can always put more window flashing tape on to protect the sheathing, if needed. One tip would be to set the depth on your skilsaw so it "almost" cuts through the siding, but not quite... then after you cut, just snap it off. Doing that preserves the wrb (housewares or felt) behind the saw cut.

When you go to install your trim, you will nail (or use trim screws) to attach your trim... and nail in pairs. If it's narrow like a 1x2, one nail in the center is fine. But one nail in the center of a 1x3 or 1x4 is asking for trouble. Nail in pairs, the nails pierce the flashing and nailing fin, that's normal.

Most mfg window installation instructions recommend leaving a gap between the window and the trim so that it can be caulked. I am not a big fan of that concept, but will usually try and leave 1/8" for expansion and contraction. That joint gets caulked last, after the trim is finished. OSI Quad (white) is my personal favorite for caulking vinyl windows that are white. Hope some of that helps.
Old 12-14-15, 07:33 PM
Join Date: Jan 2011
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Really need that picture of the outside.
Why does the trim need to be wood?
PVC trim never will rot.
Ship lap as in wooden ship lap?

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