Three things age an exterior finish here faster than almost anywhere in the country, and they compound. Ultraviolet exposure breaks down the binder holding the film together. Airborne salt deposits on the surface, holds moisture against it and works into anything porous. And wind driven rain arrives horizontally, which finds openings that vertical rain never would.
That combination is why a coating specification that is perfectly adequate in Orlando underperforms in Fort Lauderdale, and why the honest answer to "what paint do you use" is a question about the wall rather than a brand name.
What the wall is made of changes the answer
Most South Florida houses are concrete block with a stucco finish coat, which is a cement based render and therefore porous and alkaline. Some are poured concrete. A smaller number are frame with stucco over lath. All three behave differently under a coating, and the mistake that causes the most trouble is treating stucco as if it were a sealed surface.
Stucco breathes. Moisture moves through it in both directions, and that is not a defect, it is how the assembly stays healthy. Trap that moisture behind an impermeable film and it finds a way out by pushing the film off, usually in blisters that appear after a heavy rain and look like a paint failure when they are actually a moisture failure.
Acrylic against elastomeric
These are the two families that matter for coastal masonry, and the choice between them is genuinely situational.
100 percent acrylic
A quality 100 percent acrylic exterior coating is breathable, holds colour well against UV, and is far more forgiving on a wall that carries any moisture. It is the default for most stucco here. It does not bridge cracks, so surface preparation has to deal with those separately.
Elastomeric
Elastomeric is a high build, highly flexible coating that goes on many times thicker than conventional paint and stretches rather than cracking. On a wall with a pattern of hairline cracking, typically up to around a sixteenth of an inch, it bridges what acrylic would telegraph straight through, and it sheds wind driven rain very well.
The trade is permeability. Elastomeric is much less breathable, so on a wall that is taking on water from somewhere else, a leaking window head, a failed roof to wall joint, rising damp at the base, it seals that moisture in. The failure when it comes is dramatic, because a high build film that lets go takes a large sheet with it. It also needs the specified film thickness to perform, which means it is genuinely more expensive in material and in labour, and thinning it to stretch a bucket removes the only reason to have chosen it.
Primer is not optional on masonry
Bare or repaired stucco wants a masonry primer or conditioner. It does three things at once: it evens out a wildly variable absorption rate so the topcoat does not flash patchy, it binds any remaining chalk or friable surface, and it gives the finish something consistent to grip.
On new stucco the alkalinity question comes first. Fresh render stays strongly alkaline for roughly 28 days, and coating it early risks saponification, where the alkali attacks the paint binder and the film goes soft, sticky or discoloured. High pH tolerant primers exist for compressed schedules, but waiting is better.
Efflorescence, the white crystalline bloom that appears on block and stucco, is salt carried to the surface by moisture moving through the wall. Brushing it off and painting over it addresses the symptom. It will come back until the moisture path is dealt with.
The details that actually fail first
Large flat elevations are rarely where a coastal exterior gives up. The failures start at the transitions:
- Caulk joints at window and door perimeters, where movement is constant and a cheap sealant goes brittle in a couple of seasons.
- The roof to wall junction and any flashing, where wind driven rain is pushed upward rather than falling.
- Horizontal surfaces such as sills, band courses and parapet caps, which hold water rather than shedding it.
- The base of the wall, where splash back and irrigation keep the bottom courses wet far more often than the rest.
- Dissimilar metals and fixings, which corrode in salt air and bleed rust through a finish from underneath.
A specification that upgrades the sealant at those joints and leaves the field coat the same will outlast one that does the opposite.
Colour and sheen behave differently here too
Deep and highly saturated colours fade faster under this much UV, because the organic pigments that produce them are less lightfast than the inorganic ones in lighter shades. That is not an argument against a strong colour, but it is worth knowing that a deep charcoal or a saturated blue on a south or west elevation will shift sooner than a mid tone will.
On sheen, flat hides surface imperfection and is traditional on stucco, while a low sheen or satin is easier to wash down and sheds dirt better. In a salt environment the washability argument is stronger than it would be inland, because rinsing the salt off periodically genuinely extends the life of the finish.
North and east elevations green up first because they dry slowest, so a mildewcide additive earns its place on those walls even when the rest of the house does not obviously need it.
What this means for a quote
A coastal exterior estimate worth reading names the product line and sheen, states the number of coats, and says what the preparation actually consists of rather than the single word "prep". If it does not distinguish between an acrylic and an elastomeric specification, nobody has looked at the wall closely enough to decide. Our note on how to read a painting estimate goes through the rest.
See exterior painting for how we work, or request an estimate and we will come and look at the wall rather than guess from a photo.
Common questions
- Is elastomeric paint better for Florida?
- Not automatically. It bridges hairline cracking and sheds wind driven rain very well, but it is much less breathable, so on a wall taking on water from a leak or rising damp it seals the moisture in and fails dramatically. It suits a sound wall with hairline cracking and good drainage.
- How often does a coastal exterior need repainting?
- Sooner than an inland one. UV, salt and wind driven rain compound, and deep colours on south and west elevations shift first. Rinsing salt off periodically and keeping caulk joints sound extends the interval more than the choice of topcoat does.
- What is the white powder on my stucco?
- Efflorescence, which is salt carried to the surface by moisture moving through the wall. Removing it and painting over it treats the symptom. It returns until the moisture path is addressed.
- Do I need a primer on stucco?
- On bare or repaired stucco, yes. It evens out an uneven absorption rate so the topcoat does not flash patchy, binds chalk and friable material, and gives the finish a consistent surface to grip.
