New Construction window installation questions

gone_fishing

Tomorrow I am replacing a disaster window with a bigger "new construction" window. Currently the window is in a 2x4 wall with drywall type of sheathing and then foam board insulation. Because the crappy window wasn't sealed correctly I am replacing the sheathing, studs, and foam. In it's place I will put up 1/2" plywood and foam board.

My questions:
1) After I put up the plywood...do I put tar paper on before or after the foam? Or both?
2) Do I run the foam right to the opening or should I make a frame of 1x3?

Thanks!

Mark Harvey

Not sure I totally understand your issue but here are the basics. Assuming you've removed the window and the opening is the same for the new replacement window, the new window should go in from the outside. Most new windows come with a pre-attached brickmold or nailing strip (to be screwed not nailed). The existing frame should be fine unless it became wet or damaged. On the inside, the drywall should be the first thing you see, then, underneath there should be a plastic vapout barrier, then your insulation. The insulation should be tight to the frame and the vapour barrier should be sealed to the frame so there is no air movement around the wall/frame area. There may (and should be) some room between the new window and the existing frame (about 1/4" all around). This allows for levelling and plumbing the window. Once the window is shimmed and where you want it, I'd suggest spraying "Great Stuff" , a foam expanding insulation, around the 1/4" gap.
Once that is done, your inside window casing should cover the gap area and your done.
Hope this helps.

jogr

Mark, you totally forgot the most important part - flashing the exterior.

Gone fishing, your window manufacturer will have detailed instructions on how they want you to flash the windows. Follow those instructions carefully if you want them to stand behind their warranty. Most window manufacturers have a website from which you can easily download the installation instrutions.

Clutchcargo

http://www.na.graceconstruction.com/...24_Guide-B.pdf

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Mark Harvey

Jogr,
You're

gone_fishing

I know how the flash the window...thanks for the guide though...very good reference. The sheathing and studs are water damaged and have mold on them. On the exterior of the current sheathing there is rigid foam before the siding. My question was should I put tar paper over the plywood sheathing and/or over the foam. Next question, when I go to install the window do I nail right through the rigid foam or put a strip of 1x3 around the opening as a nailer?

Tom Struble

i would definatly put the paper over the ply,then either tape the seams of the foam or put a housewrap over it
you can nail the window over the foam

Clutchcargo

Put plywood around the opening so that you have something solid to nail the window to. Then butt the foam right up next to the plywood. Of coarse the plywood (or whatever nailer you use) needs to be the same thickness as the foam. Don't nail the window to the foam board. You may want the nailer a little wider if you're putting up trim after the window install.

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jomama45

Right on Tom, & I would add to the OP that I would suggest foil faced foam, as it's easier to tape seams on. New const. windows are installed over foam on new homes all the time w/o issue.

gone_fishing

Update...I ended up putting plywood, tar paper with 6" overlap, foam board, tyvek with taped seams. I used 1/2" plywood around the window as a nail strip. Almost everything went smooth. I rushed my nailer cuts so I needed to trim them back so I could install the window. Pictures to come soon.

gone_fishing

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