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Community and Q&A

Leaking 100 year old Stucco

234John | Posted in GBA Pro Help on

Good afternoon,

I am fully renovating a 100 year old home outside of Philadelphia.  The second and third floors of the home are old stucco which sit on a stone first floor.  The home has been gutted to the studs.  To this point I have revised internal framing, electrical, HVAC, and plumbing completed.  The windows have been replaced as well as the main roof, and the front and rear flat roofs.

When replacing the rear roof, the roofer was not able to counter flash, etc.  He has a lip over the stucco and caulker on top of it.  Now when it rains, the rain comes down the rear second floor of the house – straight down into the kitchen. I was able to reproduce this with a garden hose – water goes through all the 100 year old cracks – down into the below kitchen at the rear of the house.

The interior of the stucco walls remain dry, the windows were caulked and there is no water penetration. The roofer has told me to have a painter use elastomeric paint on the whole house to water-proof it.  It is stucco on wood lath, felt paper (what is left of it), and 1 inch wood plank boards.  There is no window flashing, I am caulking around the windows.

Will elastomeric painting all the stucco and sealing cracks solve my water issues?  I have noticed other spots in the house with water penetration into the first floor into the stone walls (18 inch – 24 inch Wissahickon shist.)

Should I consider tearing down the stucco and replacing with Vinyl, or cement board.?  

Please help!!  I am already over budget.

Thank you!

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  1. Expert Member


    Elastomeric paint a temporary fix, like patching old shingles with tar. There in no guarantee it will work, but it may buy you some time. You should plan on removing the stucco now, or down the road.

  2. Expert Member
    Peter Engle | | #2

    I grew up near Philly, and am familiar with these houses. FWIW, the local stone is "schist." Some of the stone around the park is little tiny garnets in it - kinda cool.
    Anyhow, these houses were sort of transitional architecture, from the old fieldstone and stucco colonial architecture to the wood-framed city/townhouse architecture of the early 1900's. When you put stucco over 2' of stone, the whole wall acts sort of like a reservoir. It stores moisture when it rains, and slowly releases it when things dry out. Over wood frame, it's entirely different, and leaks through the stucco end up inside.
    Your house is a little of each. The first floor is stone, and the few leaks you've got there are going to be related to specific holes and gaps in the various flashings and seals. You should be able to find these and fix them. the stucco is going to be tougher. Your roofer was a hack and shouldn't have taken a job he couldn't do properly.
    The only way to properly flash the transition between a roof and wall is to get the roof flashing up behind the wall cladding. With stucco, there's no alternative except to cut back the stucco 6" or so above the roof, gently pull the paper forward, and install the flashings behind the paper. With 100 year old paper, that's a real challenge, but it can be done if you find a restoration mason who works with these houses. There are probably a few nearby since there are so many houses like yours around.
    Aside from that, and in the long term, Malcolm is right - eventually you are going to have to replace the stucco. it has reached the end of its useful life. Doing it at the time of a major gut/rehab would be appropriate. You can get temporary relief with an elastomeric paint, but it is very much a crap shoot. Sometimes the paint hold water in batter than keeping it out. Sometimes, it forms giant water-filled blisters that look like warts. Sometimes it works like a dream for a year or three and then starts leaking in just a few places and you play whack-a-mole trying to find the leaks for a few years before you decide to replace the stucco.
    Modern stucco, installed over a very good water barrier, and incorporating a real drainage layer, will last another 100 years, bringing your old house forward into the next century. budgets are always the issue, but the last thing you want is for leaks to ruin all of the good things you're doing inside.
    Finally, I'll point out that it is very hard to properly seal around new windows in old stucco. Replacing the stucco will give you the opportunity to get this important detail right, too.

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