HELP! New Anderson windows on older home

mdean1120August 29, 2009

Hi, I am slowly replacing my old wooden windows with anderson 400 double hungs. I have a few questions that I am having a very hard time getting solid answers to. The house has vinyl siding over DOW styrofoam (with plywood corners). Here are my questions.

1) Do I/Should I put house wrap over the area where I am putting the next 2 windows.

2) Can I use asphalt and/or butyl flashing products over the foam board without problems. Can both types be used together?

3) Anderson suggests a dip cap. For single unit DH windows, is this needed?

Any help/suggestions would be great.

Thanks, Michael

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Is there house wrap over the sheathing now?

I would use butyl flashing because the Andersen DH windows have a nailing fin that is not sealed to the frame and there are usealed openings at the upper corners where the nailing fins are cut at the overlap of the fins. Andersen says these joints must be sealed by the installer but no one seems to do it. The easiest way to seal these joints is to allow perimeter self-adhering flashing to roll up onto the frame enough to seal the nail fin joints. This exposes the flashing edge to the sealant between the window trim and the frame. Asphalt-based flashings can be dissolved by the plasticizers in some sealants (like Ceocel 2300) causing an unsightly mess. WR Grace and DuPont make butyl-based flashings (Grace Ultra and StraightFlash respectively).

If you mean a "drip cap", it should be placed over the top of the window trim and the air/weather barrier should overlap it.

    Bookmark   September 3, 2009 at 9:03AM
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