Why Is My Stucco Cracking in Las Vegas?
Which cracks are cosmetic, which let water in, and why painting over them fails.
Stucco is the default exterior across the Las Vegas valley, and stucco cracks. A house with no cracking at all is either very new or has been recently coated. The useful question is not whether you have cracks but which kind, because one type is cosmetic and another is a path for water into your wall.
Three things drive it here. The surface bakes, and a west-facing wall in July moves through a daily temperature swing that would be unusual almost anywhere else in the country. The ground underneath moves, for the soil reasons covered in our post on cracked interior walls. And a great deal of the valley was built in a hurry with a thin single coat over foam rather than a traditional three-coat system over lath, which cracks far more readily.
Cosmetic, structural, and the ones that let water in
Map or spider cracking
A fine web across a wall face, usually from the coat drying too fast in heat. This is the most common and the least concerning. It is a coating problem rather than a building problem.
Hairline vertical cracks
Often follow a joint in the substrate behind. Cosmetic on their own, though they do let a small amount of water through and are worth sealing before a monsoon season.
Diagonal from window and door corners
The classic settling signature. Openings concentrate stress and the corner is where it releases. One or two are normal here. A consistent pattern across the house is worth a professional opinion.
Horizontal cracks and separation
Take these seriously, especially where a wall meets the foundation or where the crack has a lip you can feel with a fingernail. Water that gets behind stucco has no easy way out and will do its damage invisibly.
Cracks at control joints
Not a defect. Control joints are deliberately placed to give the wall somewhere to move. If a crack is following one, the wall is doing what it was designed to do.
Bulging or hollow areas
Tap the wall. A hollow sound over an area means the stucco has debonded from what is behind it. That section has to come off rather than be patched, because there is nothing left holding it.
Why painting over stucco cracks fails
The most common thing homeowners do, understandably, is have the house repainted and assume the cracks are handled. Standard exterior paint bridges a hairline crack for a season or two and then splits along exactly the same line, because paint has almost no ability to stretch across a moving joint.
What actually holds depends on the crack. Fine map cracking can be covered by an elastomeric coating, which is a thick flexible film built to move with the wall. Anything wider than a hairline needs to be opened up, filled with a proper patching compound, textured to match the surrounding finish, then coated. Texture matching is the part that decides whether the repair is invisible or obvious, and it is a skill rather than a product.
Debonded or bulging sections are a different job. That stucco has to come off back to sound material, the lath and paper checked, and the wall rebuilt in coats. Patching over a hollow area just buries the problem.
The monsoon problem
Las Vegas gets very little rain, and then it gets a great deal of it in a short window. That pattern is harder on a wall than steady drizzle, because water is driven into open cracks under pressure and then the surface bakes dry within hours while the moisture behind it does not.
Water behind stucco damages the paper and lath, rusts fasteners, and can reach framing. None of that is visible from outside, which is why the sensible time to deal with cracking is before summer rather than after you notice a stain inside.
If you are having exterior work done anyway, or an addition where new stucco has to be blended into old, that is the natural moment to sort the existing cracking out at the same time.
Stucco cracking in Las Vegas
Is stucco cracking normal on a Las Vegas house?
Yes. Some degree of it is close to universal here given the temperature swings and the soil. The question is always which type, not whether.
How do I know if water is getting in?
Look for staining or efflorescence, which is a chalky white deposit, around the crack. Inside, look for bubbling paint or a soft spot on the drywall on the other side of that wall. A crack you can catch a fingernail in is wide enough to take water.
Can I seal the cracks myself?
For fine hairline cracking, a good exterior sealant and a careful hand will buy you time. The difficulty is not sealing it, it is matching the texture afterwards so the repair does not read as a scar across the wall.
Does elastomeric coating fix everything?
No. It is excellent over fine map cracking and useless over a structural crack or a debonded area, where it simply hides the problem under a flexible skin.
Should I repaint or recoat?
If the cracking is cosmetic and widespread, an elastomeric recoat usually makes more sense than conventional paint. If it is localized, patch and texture those areas properly and paint normally.
Will new stucco on an addition match my existing walls?
Close, rarely perfect. Twenty-year-old stucco has weathered and the color has shifted. Blending is a craft and we are honest about what to expect before you commit.
Want someone to look at it?
Describe what you are seeing, or send a photograph. We will tell you whether it is cosmetic or structural, and we will say so plainly when the answer is that you need a different trade.
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