Mold and staining · Phoenix, AZ
Stucco Mold & Dark Stain Treatment
Black and green growth on north walls, shaded corners, and anywhere a sprinkler hits daily. We treat the wall and cut off what is feeding it.
The problem
Mold on a Phoenix wall surprises people. This is the desert. But shade plus a daily water source is all it takes, and irrigation gives it one every morning.
Left alone it spreads and darkens, and the growth holds moisture against the finish coat. That keeps the surface damp long after the rest of the house has dried, which softens the coat and invites more growth.
Cleaning alone buys you a season. We clean it, then deal with the water: the sprinkler aimed at the wall, the downspout dumping at the base, the shrub pressed against it.
- Where it shows
- North walls, shaded corners, behind dense shrubs
- What feeds it
- Sprinkler spray, downspouts, and blocked drainage
- Treatment
- Clean, treat, dry, then coat
- Also flags
- Moisture trapped inside the wall assembly
Our fix
How we treat a mold stained wall
- 01
Find the water source
Growth needs steady moisture. We look for the sprinkler head, the downspout, or the grade problem keeping that wall wet, because nothing else matters until it stops.
- 02
Clean at controlled pressure
A pressure washer on full will strip the finish coat and drive water into the wall. We use enough pressure to clean the surface and no more.
- 03
Treat the surface
A treatment kills what's left in the pores of the stucco. Skipping this is why a pressure wash alone looks clean for one season and comes back the next.
- 04
Check what's behind it
Heavy growth on one spot often means moisture is coming from inside the wall. We sound and check the area rather than assume it is only surface staining.
- 05
Coat the wall
An elastomeric coating over clean, dry stucco gives growth a tighter face to grab. It also evens out the color where the stain bleached the finish.
Sprinklers cause more of this than weather does
We can usually spot the irrigation line from the stain pattern. A fan of dark growth two to three feet up a wall, in a repeating arc, is a spray head pointed the wrong way.
That wall gets soaked every single morning, year round. Even in a Phoenix summer it never gets a chance to fully dry, and it takes mineral deposits along with the growth.
Turning one spray head is free. Doing it before we coat the wall is the difference between a repair that holds for years and one that stains again by next spring.
Other repairs
Seeing more than one of these?
- Water Damage RepairMonsoon and leak damage traced to its source, then rebuilt from the weather barrier out.
- Elastomeric CoatingA thick, flexible coat that bridges hairlines, sheds monsoon rain, and resets your color.
- Stucco InspectionA walk of every elevation before you buy, sell, or spend on repairs you may not need.
Questions
What homeowners ask us
Send us a photo of the wall and we'll tell you what we're looking at before anyone drives out.
Growth on an outside wall is a stucco and water problem, not an indoor air problem. If we find water getting inside the wall, we will tell you. Indoor testing is a job for a licensed remediation company.
Full services
The bigger jobs behind this repair
Ready when you are
Let's finish your exterior right.
New custom build, a full re-stucco, or a repair that needs to disappear into the wall? Send your plans or your address and get a straight, no-pressure bid.
Family-owned · Licensed & insured · Arizona ROC #356836 · Serving all of Arizona