Elastomeric Roof Coating & Recoats

What an elastomeric coating actually is

Elastomeric coating goes on as a thick liquid and cures into a single continuous rubber-like membrane over the whole roof. Because it is applied wet, it flows into every seam, lap, and detail and cures with no joints in it. There is nothing to come apart, because there are no separate pieces.

The "elastomeric" part matters in Arizona specifically. The membrane stays flexible and stretches with the roof as it expands in the afternoon heat and contracts overnight, every single day. A rigid coating on a desert roof cracks along that movement within a couple of seasons. A flexible one moves with it.

Where a recoat is the right answer

Coatings belong on flat and low-slope roofs — polyurethane foam, modified bitumen, built-up, and existing coated roofs that have weathered. They are a renewal of the weathering surface, not a repair for a failed roof.

The distinction is the whole thing. Coating over a roof that is dry, sound, and simply aging is excellent value: you renew the surface for a fraction of a replacement and reset the clock. Coating over a roof that is already wet underneath just seals the water in, and you pay twice. We check which one you have before we quote it, and we will tell you honestly if the answer is the second one.

Preparation is most of the job

A coating is only ever as good as what it is stuck to. The work that determines whether a recoat lasts happens before any coating comes out of the bucket.

• Clean. The roof is washed down. Coating will not bond through dust, chalk, or old failed material — and this is Arizona, so there is dust.
• Repair. Blisters, splits, open laps, and soft areas are cut out and patched before anything is coated over them.
• Detail the trouble spots. Penetrations, drains, scuppers, parapet walls, and seams get reinforcing fabric embedded in the coating.
• Prime where it's needed. Depending on the existing surface, so the coating actually adheres.
• Coat to thickness. Applied at the specified mil thickness, usually in more than one pass. Spread too thin to save material and the roof simply fails early.

The reflectivity is not a small thing here

A dark low-slope roof in Phoenix can run 160 to 180 degrees on a July afternoon. A bright white reflective coating on the same roof runs dramatically cooler because it reflects most of the sunlight instead of absorbing it.

That does two things. It cuts the heat driven down into the building, which your air conditioning was otherwise paying to remove. And it slows the thermal cycling that ages the roof in the first place, so the roof under the coating lasts longer as well.