Stucco Crack Repair in Tucson: Hairline vs Structural Cracks

Not every stucco crack is a problem

Stucco is a hard, cement-based skin, and almost every stucco home in Tucson has some cracks. The real question is which cracks are cosmetic and which are telling you that water is getting in or the house is moving. A cosmetic crack needs a careful patch and paint. A crack with a cause behind it needs the cause fixed first, or it will be back after the next summer.

Hairline cracks

Hairline cracks are thin, often look like a spider web across a wall, and tend to show up at the corners of windows and doors. They're usually from shrinkage as the stucco cured, or from years of heating and cooling in the desert sun. They're mostly cosmetic, but they still let water in during monsoon storms, so they're worth sealing.

For small cracks, Arizona home expert Rosie on the House notes that elastomeric paint can fill cracks of about 1/16 inch or smaller, while elastomeric caulk is the better fix for wider cracks because it stretches as the crack moves. The same source warns that coating an entire wall in elastomeric paint can trap water behind it (source). That's why we don't treat a thick coat of paint as a crack repair.

Cracks that need a closer look

Call someone to look properly if you see any of these:

A crack that is getting wider over the months, or keeps reopening after it was patched.
One side of the crack sitting proud of the other.
Diagonal cracks running from the corners of doors and windows, especially if those doors or windows have started to stick.
Stair-step cracks following the joints on a block wall.
Rust or water staining below the crack, or soft, crumbling stucco at the base of the wall.
Areas that sound hollow when tapped, or bulge out from the wall.

The Arizona Geological Survey lists cracked walls and foundations and jammed doors and windows among the signs of problem soils, so those symptoms together are worth taking seriously.

Full stucco re-side completed by AZ Atlas Builder Group in Tucson

What causes stucco cracks in Tucson

Heat cycles

Walls bake in the afternoon sun and cool overnight, day after day. Stucco expands and contracts with every cycle, and over the years that movement opens fine cracks, especially on south and west walls.

Settling and soil movement

Some Tucson-area soils contain clays that swell when wet and shrink as they dry. According to the Arizona Geological Survey, that alternate wetting and drying is what drives expansive-soil damage, and they recommend reducing watering around a home's foundation. Caliche, the hard cemented layer under much of Tucson, can also slow how water drains away. When the ground under a house moves, the stucco is the first place it shows.

Water

Water is behind a lot of the cracks we see: sprinklers spraying the same wall every morning, planters and soil piled against the stucco, scuppers or downspouts dumping onto a wall, and roof leaks running down inside it. Wet framing and lath swell, rust and push the stucco off.

How it was built

Missing control joints, coats applied too thin, or lath that wasn't fastened well all lead to cracking that a patch alone won't stop.

How we repair stucco cracks

Find the cause. We look at drainage, irrigation, the roof edge and any signs of movement before touching the crack.
Fix the source. That might mean redirecting a scupper, a roof leak repair, or structural repair by our own crew where framing or support has moved.
Open and fill. Cracks are cleaned out and filled with a flexible patch suited to the crack size, or cut back and rebuilt with new stucco where the material is loose.
Match the texture. We blend the finish by hand to match the wall around it.
Finish the wall. Paint or color coat the whole wall so the repair doesn't stand out.

When a crack means re-stucco

If the stucco around the crack has come loose from the wall, or water has damaged the lath and framing over a wide area, patching won't hold. In that case we'll explain the options for a partial or full re-stucco. For a sense of how each level of repair is priced, see our stucco repair cost guide.

Stucco is one of the trades our own crew does in house. We walk the walls, explain what we see, and give you a written estimate. AZ Atlas Builder Group is a licensed general contractor, AZ ROC #344537. See our main stucco contractor page for everything we do.

Common questions.

Yes. Fine cracks are common in stucco, especially in a climate with big daily temperature swings. They're usually cosmetic but should still be sealed, because they let water in during monsoon storms.

When it keeps getting wider, reopens after patching, has one side sticking out, runs diagonally from a door or window that has started sticking, or has staining or crumbling stucco around it. Those can point to water or movement.

Small hairline cracks can be sealed with the right flexible product, though matching texture and color is harder than it looks. Anything wide, growing or near water damage should be looked at by a contractor first.

It can bridge very fine cracks, around 1/16 inch or less according to Rosie on the House. Wider cracks need a proper patch or elastomeric caulk, and coating a whole wall can trap moisture, so it's not a cure-all.

Usually because the cause wasn't fixed: soil movement, water from sprinklers or the roof, or loose stucco around the crack. We find and fix the source before repairing the wall.

Yes. Our own crew does structural repair and framing, so if the crack is a symptom of movement or rotted framing, we can fix that as part of the same job.

Tell us about your project.

Takes about a minute. Photos help, especially for repairs.