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New window installation without housewrap

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Jul 14, 2013, 07:48 PM
CAH Chris
New window installation without housewrap
I am finishing an attic room above an attached garage and I would like to add a window to this room. However there is not any house wrap installed under the vinyl siding. Everything I have read about new window installation describes how the house wrap has to be incorporated into the installation to protect against water infiltration. Do I need to completely remove the siding and install house wrap or is there a way to install the window without it? I live in Ohio and this side of the house faces west.
Jul 14, 2013, 09:03 PM
Short answer: It's better with a house wrap but can be done without it.

If you can, you could add some house wrap (or some felt) around the winbdows and underneath the first foot or two of vinyl siding around the window area. Otherwise, install the window and seal as well as possible. At the very minimum, you should be able to tape over the window flanges to sheathing with Pella type rubberized foil tape.

Jul 15, 2013, 12:19 PM
Jaybee, would he tape under the bottom flange?
Jul 15, 2013, 08:01 PM
I would tape all flanges on all four sides. Sure, the most important is the top, then the sides and then the bottom but you should seal all of them. The seal is the last line of defense - the siding and trim should be keeping all the water out.

I know that the thought is that if you leave the bottom open then any water that may get in could leak out. The reality is that there is a better chance of water getting past the trim and under an untaped window (via blowing wind or pressure washing) then there is of water from elsewhere getting trapped on the bottom edge.