window install -- best practice for tying into existing drainage plane on stucco wall

[cdmllr]

My crew is working on a kitchen + bath remodel in a craftsman-style bungalow in Oakland, CA. The house is listed as being built in 1915. We are installing two windows in the West wall of the kitchen. This wall has already been remodeled -- a door was taken out and stucco'd over. The original construction is studs, tar paper, wooden stucco lath, and stucco. The newer construction is studs, tar paper, 1/2" plywood sheathing, more tarpaper, wire lath, stucco.

I have already broken the stucco back away from the window openings and cut the original wooden lath down. Now that I am down to the original tar paper, I am trying to decide how best to preserve the drainage plane of the wall. Another crew member suggested tucking 1/2" plywood under the original tar paper and essentially creating a waterproof bump-out.

The wooden stucco lath used in this house is a type I haven't seen before -- it appears to be 1x6 redwood boards milled with a shark's fin profile to grab the stucco. We used a multi-tool to carefully cut this lath away without puncturing the tarpaper.

This is my first post, please suggest any other information I should provide.

Thanks,
Casey

PANO_20140818_134134.jpg2014-08-18 13.40.01.jpg

[Allan Edwards]

Re: window install -- best practice for tying into existing drainage plane on stucco

I am trying to decide how best to preserve the drainage plane of the wall.

Thanks,
Casey

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I would remove all the stucco on that wall, the cost of applying stucco to the portion removed vs. the entire wall is negligible. In fact, taking into consideration the tie in it might be cheaper, and this would allow you to do proper waterproofing.

[Dick Seibert]

Re: window install -- best practice for tying into existing drainage plane on stucco

The wooden stucco lath used in this house is a type I haven't seen before -- it appears to be 1x6 redwood boards milled with a shark's fin profile to grab the stucco. We used a multi-tool to carefully cut this lath away without puncturing the tarpaper.

Kerfed redwood without a WRB was the common stucco installation around here until about 1910 when they started putting 15# felt over 1x8 sheathing, it worked well because walls could dry out but you never want to put insulation in a wall like that, it will become saturated and rot the walls out. Kevin ran into that above Piedmont Avenue a couple of years ago and posted this excellent picture. kfc.jpg I ran into it when I was remodeling in the 50s, but I didn't have to install insulation then. I don't know what I'd do if confronted now, even if you tear the stucco off the entire elevation you could still have a problem at the corners, the only safe thing to do is tear the stucco off the entire home and lath and stucco the home.

[kfc510]

Re: window install -- best practice for tying into existing drainage plane on stucco

Thanks for the photo credit, Dick.

I think I like Allan's suggestion; strip the entire wall.

Dick has good logic for his concerns, but you'll never get any remodel jobs on stucco houses if you take his concerns to their logical conclusions. When you graduate to $20m new construction and can dictate to the engineer the wall assemblies, then study his methods. But for us schlubs doing remodels in the dog-eat-dog market, the best you can do is the best you can do.

Detail the drainage plane carefully, which you should be able to do if you do what Allan says. Pay attention to your weeps, etc. In our climate if you do a good job, you won't get sued. At least, I haven't. (Yet.)

[larryh]

Re: window install -- best practice for tying into existing drainage plane on stucco

..What Allen said.

[kfc510]

Re: window install -- best practice for tying into existing drainage plane on stucco

..What Allen said.

One thing, I might take a small bit of Dick's advice and leave the corners intact- strip the wall to within 8-12" of the corner on the right, and perhaps stop short of the bracket on the left.

No matter what I'd get my stucco guy's feedback sooner rather than later too.

[Dick Seibert]

Re: window install -- best practice for tying into existing drainage plane on stucco

Kevin:

This case is interesting in that it's apparently a transitional installation, Casey says the home was built in 1915, I had dated the transition from kerfed redwood sheathing to 1910, note in your picture there is no tar paper, in Casey's there is, I thought they went directly from no paper and kerfed redwood to tar paper over 1x8 (I have seen 1x10 in a couple of cases) fir. I would speculate that the builder here tried to get the best of both worlds, install paper and kerfed redwood sheathing rather than chicken wire. I would have thought that he would have trapped water and even the old growth redwood would have rotted, but it appears that it has worked for the last 100 years, a far cry from our current 30 year service life homes.