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Home Improvement--General/Window leak / Stucco installation


top bay window reading
top bay window reading  
QUESTION: Hello Mr Buford,
We had an active leak above the bay window several years ago. We did ask a few window persons to check. I don’t know if  the project was too small to make any profit or it was hard to find out the problem, none of them had any follow-up. Then we hired a handyman for some other work, who told us it might be due to the stucco cracks. He applied some caulk and it did stop the leak. We applied the caulk every one or two years in the fall. However, the leak became worse after  hurricane  Sandy two years ago (we live in PA).
We were not able to contact the handyman, so we called a general contractor company who did our roof leak repair to see if it can be permanently fixed. They told us that the stucco crack is big and the window flashing is loose. The solution is to replace the stucco. I must admit that we did not do much homework on this. Because they fixed our roof leak, we had faith on them. So we had them replace the stucco last fall. However, we still saw some leak this spring. Then we contacted the contractor company for a fix. They told us since it only occurred during the heavy rain season and by sealing the screen hole and the stucco joint should fix the problem. At the same time, considering we already spent $$$ on the stucco replacement,  I did some homework for the stucco and hired a certified inspector to check the stucco. The report says “High moisture content readings were observed beneath almost all of the windows in the front bay area (the place we had the stucco replaced). High readings are typically an indication that the window sill flashing in this area are damaged or improperly installed.” We forwarded the report to the contractor company. They told us that the builder did not install moisture barrier for all of the house in our community. Because the weather was dry during the inspection time, all of the other places had good reading. However, for the replaced stucco area, they placed a vapor barrier and the water cannot get out easily, so the reading is high. He also pointed out that the plywood was not completely dry when they install the vapor barrier, or they did not think that moisture should make the plywood rotten. Their proposal was to install the sill flashing and seal the weeping hole area. I asked them if that would make the moisture reading better. They said they cannot guarantee the reading to be as low as the other areas, however, they can guarantee that we would not see any leak. There was a heavy rain after they made the correction and we did not see any active leak.
I am still a little concerned about the high moisture reading. The contractor company said the moisture will not make the plywood rotten. After some homework I do know that the contractor only did window details similar to the builder. They did not do weep screed, no ezbead, no expansion bead, although they added the draining flashing per our request based on the inspection report.  The stucco inspector suggested hiring a stucco remediation company to take out the stucco for further examination. However, I would like to avoid  further invasive check as possible as I can. I was wondering if I can take out the drywall and insulation from inside of the house and monitoring any possible water flow for a year or so as we are doing some dry wall work now. But the remodeler thinks I am crazy. What do you think? Thanks a lot!  Qin


If you are taking the inside drywall off anyway then it makes since to not cover the area and do water testing and long term observations. Unfortunately you will be looking at the back side of the outside sheathing and only see water if it gets through the seams or the sheathing rots. If you have not had water inside it may not be worth while - but you are picking a good time to try.

How old is the house? The photos make me think it is not "stucco" but and out-sulation product.
With stucco or out-sulation installation of proper flashing is critical to keeping the water out.
If there are reports of this being the case in the housing development start talking to neighbors to see if someone else has learned something. I have found that once an installer starts making a mistake he will continue making it so other houses of similar design should have the same problem.

Moisture will rot wood when it is persistent and/or high. Covering wet plywood with a vapor barrier may not have been the best of ideas since it will not allow the moisture to go anywhere but into the wood.

Unfortunately you seem to be getting run around by the people you are hiring. You need to find someone that is not going to do the repair but diagnose it (including destructive investigation) and specify out and approve the repair done by someone else.

You can consider removing and replacing the "stucco" with another siding material. This will expose everything and allow corrections to flashing. A new material will hopefully take you away from the people that have been not succeeding so far.

---------- FOLLOW-UP ----------

QUESTION: Mr. Buford, Thank you very much for your professional opinion.
Our house is 16 years old. It is a townhouse and therefore we cannot alter the outside appearance. I did hear 2 or 3 neighbors talking about window leak.
I also attach a picture taken from basement beneath the bay window area. My recollection is that the water stain (on the subfloor) was there before they replaced the stucco. The inspector took out the insulation and we saw the stain on the sheath from inside. It is not easy to monitor the basement sheath, therefore, I came out the idea to monitor the first floor.
As you know we had bad luck finding somebody to do the work. Can you please suggest what kind of profession I should search for from the yellow book?
Thanks again


The water stain in the basement looks bad.

Finding the right person will be one of the big challenges.
You will want a forensic report on the defects. The report should have photos documenting each phase of the deconstruction.

You could look for a stucco contractor with the intent you will not be making a decision on who does what until after the report is finalized.
You could look for an architect that will get his/her hands dirty doing destructive investigation.
You could look for a home inspector.
Search the internet for "structural forensic engineer, water damage, pennsylvania" and see where that leads you.

Whoever you get have them provide you a sample report on a leak investigation so you have some idea they can prepare such a report. Also get some client references from 5 years back to see how the forensics were used and if the engineer was on target.

Good luck.

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Thomas Buford


Licensed Architect in Virginia since 1984.
New Homes, Additions, Alterations, Outbuildings, Failure Forensics;
Small Construction Projects; Remediation and Repair


Architectural design, planning, construction and repair.
• Schematic Design
– objectives statement
– space planning
– feasibility study
– structural, mechanical, plumbing
and electrical system integration
• Permit Drawings
• Construction Drawings
• Contract Documents
• Construction Administration
– construction management
– pre-qualification of bidders
– bidding
– general and/or sub contracting
– construction progress and
construction contract review and interpretation
– pay request certification
• Construction failure diagnostics
– water intrusion
– structural failures, ...

Due to life safety concerns regarding some aspects of construction I may not be able to help with all questions.
I do not answer structural specification questions without a site visit.

Arlington Journal

5 year Bachelor of Architecture from
Virginia Polytechnic Institute and State University (VPI-SU)

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