Water Coming In Around the Windows: A Stucco and Wall Repair
Thermal imaging found it entering above the windows near the roofline, which is not where anybody was looking.
The symptom and the actual location
The client had a persistent leak around the windows on the front of his house, the elevation facing southwest. He called us to analyze it rather than to fix something specific, which was the right call, because the windows were not where the water was getting in.
A thermal survey of the wall showed water entering above the windows, up near the roofline, then travelling down inside the assembly and wetting the interior walls on its way. By the time it appeared as a stain near a window frame it had already been inside the wall for a while and several feet above where it showed itself.
That gap between where water enters and where it appears is the single most expensive misunderstanding in this kind of repair. Every dollar spent sealing around the window in that situation is a dollar spent in the wrong place, and the wall keeps getting wet while everyone congratulates themselves.
“I had a pretty serious problem with leakage around the windows on the front of my house facing southwest. I called Construction by Mirage to give me an analysis and they came to perform a thermal test that indicated there were some problems with water coming in above the windows near the roofline and was seeping down and damaging my walls on the inside. They removed all the drywall, treated the areas, and replaced the damage. They then had to remove the outside stucco that was not sealed properly and replaced it with new wood, membranes wire and stucco. They were clean, fast, timely and efficient.”
Chris P. · Google review, 2021
How a stucco wall is supposed to work
Stucco is not the waterproofing. That surprises most homeowners, and it is the thing worth understanding before you approve any repair to one.
A conventional stucco wall is a drainage plane. Behind the stucco there is a weather-resistant barrier lapped from the bottom up so that every sheet sheds onto the one below it, then metal lath, then the stucco itself in coats. Water that finds its way through the stucco, and some always does, is supposed to run down the face of that barrier and back out at the bottom of the wall.
So the barrier is the thing keeping your house dry, and the barrier is behind the stucco. That single fact decides everything about what a real repair costs, because you cannot correct it from outside without taking the stucco off.
Five things that stack up on a valley elevation
Flashing that was never integrated
The flashing above a window has to tuck under the barrier so water running down the wall passes over the top of it and back out. Lapped the other way, every drop that lands above the window is directed straight into the wall.
Sealant used as the primary defense
Caulk at the head of a window is a backup, not a system. Where it is the only thing standing between the weather and the framing, the wall has a service life measured by the caulk.
Southwest exposure
That elevation takes the full afternoon in a place with brutal UV. Sealants and any exposed membrane age faster on that wall than anywhere else on the house, so it is normal for one elevation to fail while the other three look fine.
Wind-driven rain
Rain here is infrequent and then arrives sideways in a monsoon cell. Water hits a vertical wall with real force for twenty minutes, which finds paths that a gentle drizzle never would.
Movement cracks
The valley’s soils move, and stucco cracks. Most of those cracks are cosmetic on their own, but on a wall whose barrier is already compromised they are one more way in. Our piece on what stucco cracks in Las Vegas actually mean covers how to tell the two apart.
Both sides of the wall, in order
Find it before touching anything
A thermal survey shows where the wall is wet, which is not where the stain is. Diagnosis first is the difference between one repair and three.
Open the inside
The affected drywall came off so the framing and the back of the assembly could be seen and dealt with properly. Closing a wall up over something you have not looked at is how a repair comes back.
Take the stucco off the failed area
The only way to correct a barrier is to remove what is covering it. This is the step homeowners resist and the step that decides whether the job is finished or postponed.
Rebuild the assembly in the right order
New sheathing where it was needed, new membrane lapped so it sheds correctly, new lath, then stucco in coats. Every layer laps over the one below it, which is the whole principle and the thing that was wrong in the first place.
Close up, then repaint
Interior walls put back and finished, exterior stucco cured and painted. He had us repaint the whole exterior while the scaffolding was up, which is the sensible time to do it: a patch on a wall that has faded for fifteen years never matches, and paint is cheap next to access.
Why the cheap version does not work
The tempting repair is to seal the outside of the wall. Caulk the head of the windows, patch the cracks, put a coat of elastomeric over the elevation and see what happens next monsoon.
Sometimes that buys a season. It does not fix a barrier that is lapped wrong or missing, because that barrier is still behind the stucco doing the same thing it was doing before, and now it is doing it under a coating that also slows the wall’s ability to dry. What you have bought is a delay and, occasionally, a wall that stays wet longer than it used to.
We would rather tell you that at the estimate than take the smaller job and be back. If the diagnosis says the assembly is sound and the problem really is a failed sealant joint, that is a genuinely small repair and we will say so.
Wall and stucco leaks in Las Vegas
How do I know it is the wall and not the roof?
Often you do not, from inside. Water travels along framing and shows up somewhere convenient rather than somewhere useful. That is what the thermal survey is for, and it is worth doing before anybody quotes you a repair.
Can you just re-caulk it?
If the diagnosis says the assembly behind the stucco is intact and a joint has failed, yes. If it says water is entering above the window and running inside the wall, caulk changes nothing except the date you deal with it.
Will the new stucco match the rest of the house?
The texture can be matched closely by hand. Color is a different question, because fifteen years of Las Vegas sun changes a wall, so an exact match on an aged elevation is not realistic. That is why repairs of this size usually end with painting the elevation or the house.
Does the whole wall have to come off?
No. It comes off where the assembly failed and far enough past it to reach sound material and lap the new barrier into what is already there. Guessing the boundary too tightly is how the same wall leaks again at the edge of the patch.
Is this something you find in newer houses too?
Yes. Flashing detail at the head of a window is a workmanship item, not an age item, and a wall built quickly during a boom can fail sooner than one built carefully thirty years earlier.
Who pulls the permit for this kind of repair?
We do, where the scope needs one, in our name and with the inspections booked. That is the same on a wall repair as it is on an addition.
Who did this work
A repair on both sides of a wall needs one party responsible for the whole assembly rather than a stucco crew and a drywall crew who never meet. That is why this ran as a general contracting job in Las Vegas: one price, one sequence, and one contractor accountable for whether the wall is actually dry at the end of it.
The same instinct applies to problems that look nothing like this one. An events company whose garage was cooking their equipment also arrived as a purchase decision and turned out to be a building envelope question.
Have the same problem at your place?
Tell us what you are seeing. We will look at it, tell you what is actually going on, and hand you a written price and a finish date for nothing.
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