Cracks, blisters and holes: which ones matter and which can wait

Start with one question

For every mark on the wall, the question is the same: is water getting in? A crack that lets water in matters. A crack that does not can wait. A blister always means water is already in. A hole is an open door. Everything below follows from that.

Cracks

Hairline cracks

Fine lines you can barely get a fingernail into, often in a random pattern or around corners of openings. On cement stucco they are normal and come from the plaster curing and the house settling. On EIFS they are less normal, since the coatings are flexible, and usually mean a thin base coat or a joint that should have been there. Urgency: low. Seal them when you next have sealant work done, or fill them before a recoat.

Cracks from the corners of windows and doors

Diagonal cracks running from the corners of openings are stress cracks: the opening is where the wall is weakest and movement concentrates there. Common, and repairable in a way that allows for more movement so they do not come back. Urgency: medium. Water will find them.

Wide or spreading cracks

A crack you can put a coin in, or one that is longer than it was last year, is movement in the structure or a base coat that has let go. Have it looked at. Urgency: medium to high, and the cause matters more than the crack.

Stair-step cracks on stucco over brick

Cracks that follow a zigzag pattern are the mortar joints of the brick behind telegraphing through. The brick is moving or the pointing has failed. The stucco is the messenger.

Cracks at the line of a band or moulding

A straight crack where a moulding meets the wall means the piece was not meshed in. Water gets behind the moulding. Fix it with the next sealant round.

Blisters and soft spots

A blister is the finish, and sometimes the base coat, lifting off what is underneath because water is behind it. Press it and it gives. There is no version of a blister that is fine. The water came from somewhere above: a window joint, a failed flashing, a crack, a moulding. The repair is to open the area, dry and repair what is behind, close the entry point and rebuild. Painting over a blister hides it for a season. Urgency: high, and higher the longer it has been there.

A soft or hollow area without a visible blister is the same thing a little earlier. Tap the wall around any stain; the sound changes where the layers have separated.

Stains

Dark streaks running down from the bottom corners of windows are the most useful sign on a stucco house: the window joint or the sill is passing water, and it is running down inside the finish. Rust stains come from a fastener or a flashing corroding behind the wall. Green or black staining is algae or mould on a wall that stays damp, often under a leaking gutter or beside a sprinkler. Urgency: find the water source.

Holes and impact damage

A hitch, a ladder, a lawn mower, a ball or a woodpecker. Any hole through the finish and base coat is an opening for water and should be closed at once. The repair is straightforward: cut back to sound material, replace board if it is damaged, mesh, base coat and finish. Corners and low walls that keep getting hit are rebuilt with extra layers of mesh. Urgency: high because it is open, not because it is hard.

Chalking and fading

A finish that leaves powder on your hand or has faded unevenly is at the end of its surface life. The wall is not failing. It is telling you a recoat is due in the next few years. Urgency: low.

Sealant that has let go

Not damage to the stucco, but the cause of most of it. Caulking that is cracked, shrunk, hard or pulled off the frame has stopped working. Replacing it before the water gets in is the best value work on the house. Urgency: medium, rising every rainy season.

What can wait, and what cannot

• Call this week: blisters, soft spots, holes, water inside the house near a stucco wall.
• Call this season: cracks from window corners, wide or growing cracks, stains under windows, sealant that has failed.
• Plan for it: hairline cracks, chalking, fading, a look you are tired of.

What the repair should include

Whatever the damage, a proper repair finds and fixes the cause, cuts back to sound material, rebuilds the layers with mesh, seals the joints nearby, and matches the finish. If a contractor offers to skim over a blister or caulk over a crack without asking where the water came from, the problem will be back next spring with interest.

Send us a photo of the mark that worries you. We will tell you which category it is in, and if it needs a visit, when.