Stucco cracks - cosmetic or should I worry?

Usually cosmetic

• Fine, random, web-like cracking across a wall — shrinkage as the stucco cured.
• A straight crack sitting over a control joint, which is the joint doing its job.
• Hairline cracking around a patch, where old and new meet.

Worth investigating

• Diagonal cracks running from the corners of windows and doors.
• Stair-step cracks that follow the block joints.
• Horizontal cracks.
• Anything wide enough to take a coin.
• Any crack with staining, efflorescence or bulging around it.

Tap the area. A hollow sound means the stucco has delaminated from the substrate and water is already behind it. On frame construction that can mean rotted sheathing, which is a repair rather than a patch.

The Florida-specific one

Cracking along the band where frame meets block is common on two-storey houses here. That joint moves, because the two materials behave differently, and it needs a proper detail — a joint designed to move — rather than a bead of caulk that fails again next summer.

What I would do about it

1. 1Photograph the pattern, with something for scale, and note which elevation it is on.
2. 2Check inside for matching cracks at the same corners, and check doors for square.
3. 3If it is the cosmetic kind, repair with a flexible sealant designed for stucco and repaint that elevation.
4. 4If it is the other kind, get it looked at before you paint over it, because paint hides the evidence and not the cause.

Matching interior cracks at door corners have their own answer: why they keep coming back. And if you are about to repaint, how often a Florida house needs it.

Repairing it so it does not come back

1. 1Open the crack slightly rather than painting over it, so the repair has something to key into.
2. 2Fill with a material that flexes, not a rigid patch that becomes a new crack beside the old one.
3. 3Re-texture to match, which is the part that separates a good patch from a visible one.
4. 4Prime the repair, then paint the whole elevation rather than spot-painting.

If the same crack returns within a season, the movement behind it was not addressed and the repair is not the problem. That is the point to stop patching and find out what is moving.