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Existing 1989 Andersen Windows - no drip caps....retrofit?

Existing 1989 Andersen Windows - no drip caps....retrofit?


Old 05-10-13, 05:37 AM
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Join Date: May 2013
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Existing 1989 Andersen Windows - no drip caps....retrofit?

Hi Everyone,

I recently purchased a 1960 built colonial. All of the windows are Andersen double hung, from 1989 (according to the engraving). The house is sided with the original striated cedar, with undercourse.

I noticed that none of the windows have any drip cap over them. The window protrudes a bit from the siding, and there is caulk run along the top of the window where the shingles come down to meet it. I peaked behind one, and verified that as expected the windows have a nailing flange. But the nailing flange lays over the black tar paper, and then the undercourse and shingles lap over the nailing flange. This does not seem correct to me. The house I grew up in, built by my grandpa in 1984, has the same shingles and Andersen windows, and above every window is a metal drip cap.

Can I easily retrofit a drip cap? I'm good with removing/reinstalling shingles. But, if the drip cap sits on top of the tar paper, I don't see how it would be any better than the existing nailing flange. Would I install the drip cap over the window, and then tape the top of it to the tar paper with some kind of sealing membrane tape?

I also have noticed that the sheetrock is kind of sloppy below some windows, like repairs had been done. But, it's hard to say if this was from old windows leaking (likely storms) or work that was done during the install of these Andersens in 1989.

Thanks for any advice you can give, and pics or links to the proper flashing/drip cap to get for this kind of retrofit would be great!

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Old 05-10-13, 06:37 PM
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If you don't have any water leaks, I would leave it alone.
Old 05-10-13, 07:11 PM
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if the drip cap sits on top of the tar paper, I don't see how it would be any better than the existing nailing flange.
I think you hit the nail on the head. There is no difference, and you don't necessarily need a drip cap in addition to the nailing fin. If you had brickmould trim surrounding the windows, then you would want a drip cap (z-flashing) over the top piece of brickmould.

So, I agree with Pulpo. If it ain't broke (doesn't leak) why fix it?

If those windows were installed today using current methods, a flexible flashing could be used to form a pan flashing in the bottom of the rough opening, then the window would be installed, the nailing fins would be taped to the housewrap on the sides, while the housewrap would be slit on top and folded up so that the top nailing flange could be taped directly to the sheathing. Then the housewrap would be folded back down over that top piece of flashing tape, so as to shed water. There are variations on that... bottom line is to follow the mfg's installation instructions.

As your windows are currently installed, if any water DOES get behind the siding (and you'd probably know it if it was, because it would be leaking in around the windows) water would be able to run behind the top nailing fin, leaking in at either the top or bottom of the window, or both.

None of the window flashing tapes that I know of will stick to tar paper. The solvents in the tar paper will repel the flashing tape within 24 hrs/once the tar paper gets hot. So I wouldn't suggest you try that.

A properly installed drip cap is indeed tucked behind the weather resistant barrier (WRB), and when siding is installed around it, you leave a gap between the siding and the drip cap so that any water behind the siding can escape. But most guys can't stand to leave it uncaulked... or a homeowner that doesn't know any better will caulk it shut, thinking he is keeping cold air out or something.
Old 05-11-13, 04:14 AM
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I also have noticed that the sheetrock is kind of sloppy below some windows, like repairs had been done.
Pics would help us understand the damage and what needs to be done to fix it - http://www.doityourself.com/forum/el...-pictures.html

btw - welcome to the forums!
Old 05-12-13, 07:37 PM
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Join Date: May 2013
Posts: 7
Thanks for all of the advice guys.

I guess the "if it ain't broke" adage makes sense here. The windows were installed in 1989, so if there were any water intrusion issues, there would be noticeable damage. The whole interior of the home was repainted before I bought it, so stuff could have been fixed. I will get some photos up soon of thr spackle/drywall repair work that seems to be evident below some of the windows. Hard to say if it was past water damage, or just touch up work that was done back in 1989 when removing the old windows and installing the new.

I have had the opportunity to see inside the wall below 2 random windows in the home.

1 is in the garage, which is not sheetrocked. 1 wall that has a window is just lined with pegboard. I noticed the very bottom of the pegboard has some moldy looking spots where it meets the bottom sillplate, right above the cement footing. I removed the pegboard to inspect since I figured it would give me an easy way to view an example of how the window flashing or lack thereof was performing. All the wood/framing in there looked fine...no rot. So, no signs of significant water damage over the 60 year age of the house and 23 years of these particular windows. The mold could have been from the window being open, or some leaks from the old windows maybe? (I'll get a pic of this soon as well).

I also had to replace some sheathing in 1 spot, happened to be below a window. I went to remove/replace some bucked shingles and found that it was actually the plywood sheathing that had buckled. Removed and replaced the section (was all warped, and pretty much splintered/disintegrated as we removed it). I figured this was a sign of water damage, but again, the studs and box looked perfectly fine. There is 1 more spot on the house with apparent sheathing bowing, but it is NOT below or near a window. It is only 3/8" sheathing, so perhaps it is easy for it to buckle.

Anyway, I'll get some pics up of the windows/sheetrock below them/and that pegboard mold pic from the garage. I know I typed a lot! :P Thanks again!!

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