Choosing exterior paint for a Salt Lake home

Most exterior paint failures trace back to one of two decisions: the surface was not prepared, or the wrong product went onto it. The first is covered in the prep sections of our other guides. This one is about the second: which coating suits which material, given high-altitude sun and a winter that cycles across freezing constantly.

The topcoats

100 percent acrylic latex

The workhorse for wood siding, trim, fiber-cement, and previously painted surfaces. Modern acrylics stay flexible through temperature swings, which matters enormously in a climate that expands and contracts materials daily. They also resist UV better than cheaper vinyl-acrylic blends, which is the specification that counts most at 4,300 feet. Premium lines carry more durable resin and higher pigment loading, and the price step from contractor grade is small relative to total project cost.

Elastomeric coating

For stucco and masonry with hairline cracking. Applied at many times the thickness of ordinary paint, it forms a thick flexible film that bridges hairline cracks as the wall moves. The trade-off is vapor permeability: elastomeric holds moisture in, so it belongs on walls that are dry and staying dry, not walls with a moisture source behind them.

Breathable masonry acrylic

The alternative for stucco and masonry that needs to release vapor outward. Less crack-bridging capability, far better moisture management. Choosing between this and elastomeric is a wall-condition judgement made on site, and a bid that names one without looking at the wall is guessing.

Waterborne alkyd enamel

For doors, shutters, and high-touch trim. Handles like latex, cures hard like oil, levels smooth. This is also the cabinet-interior standard. Ordinary wall paint on a front door scuffs and blocks within a season.

Penetrating and semi-transparent stains

For decks, fences, and exposed structural wood. These soak in rather than forming a surface film, so they wear by fading instead of peeling. In a climate where horizontal wood sits under snow, that difference decides whether maintenance is a wash-and-recoat or a full strip. See the deck staining guide.

The primers, and when each is required

• Standard exterior primer: for bare wood in good condition. Seals the surface and gives the topcoat something uniform to bond to.
• Stain-blocking primer: for cedar and redwood, which bleed tannin through ordinary primer and stain the finish coat from behind. Also for rust bleed at fasteners and water-stained wood. Common on mid-century Salt Lake trim.
• Bonding primer: for glossy or difficult surfaces: old oil-based paint, factory finishes, thermofoil, and chalked aluminum siding. Without it the new coat sticks to the old finish rather than the substrate.
• Masonry primer or conditioner: for stucco and previously painted masonry, neutralizing the surface and improving adhesion.

Surface by surface

Wood siding and trim

Premium 100 percent acrylic over spot-primed bare areas, with stain-blocking primer where the wood is cedar or redwood. Two coats. Seal end grain during prep.

Unpainted brick

Nothing. Leave it. This is the local consensus and the preservation guidance in historic districts, because coating porous brick traps moisture that then freezes behind the face and spalls it. Paint the wood and cut clean lines at the masonry. See the brick trim guide.

Previously painted brick

Once brick has been painted, the reversal is impractical, so the maintenance path is a breathable masonry acrylic that lets as much vapor out as possible. Elastomeric on already-painted brick is a moisture gamble.

Stucco

Wash, treat efflorescence, rout and patch cracks with elastomeric patching compound, then either elastomeric or breathable masonry acrylic depending on wall condition. Two coats at the spread rate on the data sheet, since elastomeric performance depends on achieving film thickness.

Fiber-cement

Holds paint better than wood because it does not move with moisture. Factory-finished boards typically want their first repaint around 12 to 15 years in this climate, sooner on high-exposure bench elevations. Standard premium acrylic, with attention to caulk at the butt joints.

Aluminum and steel siding

Common on 1960s and 70s Salt Lake homes. The factory finish chalks heavily over decades, and that chalk must be washed off and the surface treated with a bonding primer, or the new paint adheres to powder and sheets off within a couple of years. Done properly, painted aluminum siding holds up very well.

Metal railings and ironwork

Rust-inhibitive primer over cleaned metal, then a direct-to-metal or enamel topcoat. Skipping the rust treatment means the rust keeps working under the new paint.

Where the money is well spent

In rough order of return per dollar in this climate: preparation first, always. Then film build, two proper coats rather than one thin one. Then premium topcoat over contractor grade. Then the specialty products where the substrate demands them. A premium can of paint over unprepared, chalky siding will still fail; a mid-grade paint over excellent prep will not.

For how those choices interact with sun exposure and color, see the UV guide.