Why exterior paint fails early in Northwest Georgia

Read the wall before you buy paint

Paint fails in recognizable ways, and each one points somewhere different.

It fails in an order too, and where a wall sits in it decides the job. Gloss dulls first, with the film still whole. Then color fades and the surface chalks, still protecting the wood but now a bonding problem. Then fine checking a fingernail finds before an eye does, then cracks at a joint or a nail line, then flakes lifting and bare wood showing. Once the wood has grayed and the grain has raised, sanding comes before paint.

• Peeling in sheets to bare wood: bond failure. The coat went over chalk, dirt or gloss it never gripped.
• Peeling back to an older layer still stuck fast: the coats are not compatible, or moisture moved between them.
• Blisters with a damp patch underneath, worst after rain: moisture pushing out from behind the film.
• Powder on your palm, color gone flat: chalking, a bonding problem for whatever goes on next.
• Black speckling, heaviest on shaded walls and under the gutter line: mildew on the paint, not paint failing.
• Rust dots at nail heads, brown streaks below knots: fasteners or the wood bleeding through the film.

Chalk, and the walls that chalk first

Sunlight breaks the binder down and leaves loose pigment on the film. That is chalking, and your palm finds it: dusty, the color of the house.

Chalk is not a failure by itself. An old wall can chalk and still be sound. It becomes a failure the moment somebody paints over it, because the new coat is not bonded to the wall. It is bonded to powder that is bonded to nothing. Washing is the fix: detergent, dwell time and a rinse rather than pressure alone. Where it will not fully wash out, a bonding primer made for chalky surfaces beats another topcoat.

Elevations do not age together. South and west walls take the most direct sun and the hottest part of the day, so they chalk and fade first. Repainting only those walls is legitimate, as long as the work runs to a corner rather than blending mid-wall. Paint them in the morning: a wall hot from afternoon sun skins over before the coat can flow out and bond.

Wet wood pushes paint off from behind

Paint film holds water out. It does not hold water in. Wood wet behind the film turns that moisture to vapor as soon as sun hits it, and vapor leaving wood lifts paint off the surface it is stuck to. That is the blister with the damp patch under it, and it is why a careful repaint can still fail.

A wall that felt dry at eight in the morning has taken moisture back on by evening. Shade is what stretches that out. A wall with no direct sun dries long after the one across the house, so the same rain sits on it far longer. Damp ground under a house is a crawlspace problem rather than a paint one, and it still reaches the lowest boards.

Handle the water before the paint. A gutter running over puts roof water down the wall behind it every storm. Then check the wood rather than trusting it: a pin type moisture meter is a small hardware store purchase.

Mildew is growth, not damage

The black speckling on a shaded wall is mildew, a fungus growing on the outside of a film that is usually sound. It feeds on the dirt, pollen and binder on the surface, and needs what any growth needs: food, damp and shade. That is why it collects on north walls, under the gutter line and behind shrubs grown against the siding.

Telling it from dirt takes a minute. Dab a spot with a household bleach solution and wait. Mildew lightens or disappears. Dirt does not move.

The mistake it causes is repainting. Mildew is alive, so a fresh coat buries a living colony and it grows back through in the same pattern, because new paint feeds it better than the weathered coat did. Kill it, wash it off, and on a sound film that is the whole repair: no scraping, no primer, no gallon of anything. Exterior paint carries a mildewcide that slows regrowth. It does not sterilize a wall it was rolled onto. What settles it for good is light and air: shrubs cut back off the siding, and whatever holds that wall wet dealt with.

Two surfaces that change the prep

New pressure treated lumber arrives soaked with the treatment solution, and it is nowhere near ready for paint or solid stain. The calendar is not the test. Water is: sprinkle some on the board. If it beads and sits, the wood is still full. If it soaks in, the surface is ready.

Old paint is the other one. Lead was in house paint until 1978, so anything built before then may have it, and Rome has plenty of housing older than that. Test kits are sold at hardware stores. It changes the prep, not whether you can paint. Power sanding, open flame and washing loose paint into the yard turn a stable surface into dust where people and pets live. Contractors disturbing paint in pre-1978 housing work to federal lead safe rules, so it is fair to ask. Gentler prep instead: wet scraping over a drop cloth, hand tools rather than power ones, and a bonding primer over a sound old surface.

Most of this is a homeowner job

Exterior painting is genuinely doable, and the parts that decide whether it lasts are the ones anybody can do: wash the wall, let it dry, scrape what is loose, feather the edges of sound paint, spot prime every bare patch.

The most useful thing on a smaller repair is patience with drying. Wash one weekend, paint the next. Killing and washing mildew off a sound wall is a bucket, a brush and an afternoon, and on a whole film that is the entire repair.

Where it stops being a good homeowner job, and where we usually come in: upper story walls off ladders on sloping ground. Rotten fascia, soffit or siding, which has to come out before anything is painted. And pre-1978 surfaces needing heavy scraping, though a homeowner on their own house is not bound by those rules, which does not make the dust any different.

So does it need doing now

If bare wood is showing, do it now, or at least prime the bare patches and paint when the weather suits. Exposed siding and trim take water on, and water in the boards is what turns a paint job into a carpentry job.

If it is blistering, do not repaint yet. Find the water first: a gutter, a downspout, a sprinkler head. Repainting over a live moisture source repeats the failure on your schedule instead of the weather's.

If the film is intact and what you have is chalk, fade or mildew, it can wait, and the mildew may not need paint at all. What decides it is whether the film is still covering the wood. While it is, you have a cleaning job and a color decision. Once it is not, the clock is on the wood.

Questions that come with this one