Stucco Repair and Coating

The Plaster Comes First, the Color Comes Last

Nearly every stucco call we take starts with a description of how the paint looks. Blistering above a window. A dark patch on the north side that never dries out. White powder washing down from a crack. Chalky finish that comes off on your hand.

None of those are paint problems. They are wall problems wearing a paint costume, and the useful work is on the plaster and on the details around it. Once that is right, the coating is straightforward. Put the coating on first and you have spent real money on a countdown.

Reading the Cracks

Cement plaster cracks. It cures by shrinking, it moves with temperature, and a hundred year old wall has been through a lot of both. What matters is which kind of crack you are looking at.

Fine crazing spread across a whole field, like a road map, is shrinkage. It is usually shallow, it usually is not going anywhere, and it takes a flexible patching material worked into the crack and floated back to texture. On a badly crazed elevation that takes wind driven rain, a thicker bridging coat can be the correct answer, with the important caveat that the wall has to be able to dry somewhere else.

A single crack running diagonally from the corner of a window or a door is different. That is stress concentrating at an opening, and it is often moving with the seasons. Filling it with a rigid material means it reopens on the same line, usually within a year. We cut it out, address what is behind it where we can get at it, rebuild in coats, and use a material with enough flex to survive the next cycle.

Horizontal cracking that follows a floor line on an apartment building is usually structural movement between levels. That is a conversation about expansion joints, not a patching job, and we will tell you when we think you need somebody else to look at it.

Patching So the Repair Disappears

A stucco patch is only as good as its texture match. The finish coats on the older houses here were floated by hand with a sponge or a rubber float, and they have an irregularity to them that no spray hopper reproduces on its own. A perfectly flat, smooth patch in the middle of a sand float wall is visible from the sidewalk in raking afternoon light, even after it is painted.

So we mix a sample, float a test area somewhere inconspicuous, let it cure properly and then look at it in the same light as the wall it has to match. Cement changes color as it cures, which is why a patch that looked right when wet reads as a pale rectangle a week later.

Where a cutout is involved, from a plumbing repair or a window replacement, we rebuild the full thickness. Lath lapped and tied into the surrounding lath, scratch coat, brown coat, finish coat, each one given its time. Filling a cutout with one thick pass of patching compound is faster and it always telegraphs.

Choosing a Coating for a Coastal Wall

Once the plaster is sound, the coating decision comes down to permeability, which is simply how easily water vapor passes through the dried film.

Mineral silicate finishes sit at the open end of the range. They react chemically with cement plaster rather than sitting on top of it as a film, they hold color well under strong sun, and they let a wall keep breathing. They need a compatible substrate, so they are not a universal answer, and they are not the right choice over an existing sealed film unless that film is coming off.

High permeability acrylic systems are the middle ground and cover most of what we do. Good ones shed liquid water while staying reasonably open to vapor, and they tolerate a wider range of existing surfaces than a mineral system does.

Elastomerics sit at the closed end. They are thick, flexible and genuinely useful over crazing on an exposed elevation, and they are also the single most common cause of the blistering we get called out to. If a wall is wetting from behind, from a leak, from irrigation, from a planter bed built up over the weep screed, a heavy elastomeric turns a slow problem into a fast one.

Salt, Rust and Efflorescence

Close to the water, two more things show up. Metal corner bead and exposed lath rust, and rust occupies more space than the steel it came from, so it pushes the plaster off in a line. That has to be cut back, treated and rebuilt, not skimmed over.

Efflorescence, the white bloom, is dissolved salt left behind when water evaporates at the surface. Washing it off is cosmetic. It returns as long as water keeps traveling through the wall, so we treat it as a diagnostic rather than a stain and go looking for the entry point.

What the Job Looks Like

We wash the wall, let it dry properly, then open and repair what needs it. Repairs cure. We prime where the substrate calls for it, then apply the finish system in the coats the manufacturer specifies rather than the coats that fit the schedule. Dew point and surface temperature get checked before each coating day, which on a foggy week means we sometimes lose a morning.

Call (424) 432-0305 and tell us what the wall is doing. That is usually enough for us to know what we are walking into.