Roof Coating

How a roof coating project runs, step by step

Roof coating takes prep before the first gallon goes down. We start with a roof condition survey, since wet insulation or a spongy roof deck will push moisture up and blister the new surface from underneath. Here is the sequence our crews follow.

1. The roof condition survey comes first: we walk every square, probe the decking by hand, and note ponding water, seam splits, and rusted fasteners.
2. Repairs happen before any coating: we cut out blisters, dry the substrate, and patch openings with roof cement and reinforcing fabric.
3. A primer goes down wherever the existing surface has oxidized to chalk, or where old tar and bitumen residue would fight adhesion.
4. Seams and flashing get resealed, and we lay a continuous flashing bead around every pipe boot, scupper, and parapet.
5. The base coat is applied at the manufacturer's published coverage rate, not stretched thin to save a bucket of material.
6. A reflective finish coat goes on by roller or airless spray, and that top film is what delivers the tensile strength and sun resistance you are paying for.
7. Cure time gets respected, so nobody walks a rooftop that has not set and scuffs the surface back to square one.
8. Cleanup closes the job: dumpster loaded, debris swept with a magnet, and gutter and downspout checked before we leave.

Which coating material fits your roof

Material choice comes down to what the roof is made of and how wet it stays. An acrylic coating is the cheapest route to a reflective white surface, but it re-emulsifies where water sits.

A silicone coating handles standing water and stays flexible for years. Polyurethane gives the hardest film. Any roofer can spray white paint; a licensed and insured roofing contractor documents the substrate first.

• Elastomeric coating bridges hairline cracks and moves with a metal panel through a 100-degree afternoon, which is why most building owners land there.
• Acrylic coating resists UV degradation well, but we never spec it over a ponding area because it softens and lifts.
• Silicone coating is the pick over a built-up roof or modified bitumen that holds water, since it cures without a solvent flash and will not peel.
• Polyurethane coating adds abrasion resistance on a rooftop that HVAC crews walk every season.
• Primer systems and mastic tie the new film to a chalky, oxidized substrate so the whole coating does not flake off inside a year.
• Systems from GAF Unisil, Henry, and Tropical Roofing get installed to their published coverage rate and warranty terms, not to whatever looks thick enough.

What we find up there, and what failure looks like

By the time a roofline looks bad from the ground, the membrane is usually further gone than it looks. We photograph what we find, show you which items are urgent, and tell you which ones can wait a season or two.

• Ponding water that still sits 48 hours after a monsoon means the roof has settled or the drains are undersized.
• Blistering reads as bubbles under the membrane, and each one is trapped moisture cooking in the sun.
• Alligatoring and chalking mean the top layer has oxidized far enough that a coating needs primer to bond.
• Seam splits let water wick sideways under a membrane, so the leak shows up far from the actual tear.
• Granule loss on an asphalt shingle roof signals end-of-life wear, and coating will not save a shingle that is already bare.
• Rust and corrosion on a metal panel roof begin at scratched paint and exposed fastener heads.
• Rot and decay in the sheathing feel like a soft spot underfoot or a sag along the roof deck.
• Peeling and flaking on the fascia usually points to water running behind a lifted drip edge.

Roof components we check, and how each one affects the coating

A coating job touches almost every part of the roof system, from the eave to the ridge. Here is what we check and how each piece affects the bond.

• The roof deck, sheathing, plywood, and OSB get probed by hand, because soft decking has to come out before any coating will hold.
• Trusses, rafters, joists, and the ridge beam show trouble as a dip that collects ponding water, so we flag sagging framing for a structural look.
• Decking is also the substrate, and a damp substrate pushes moisture out through a fresh film, so we moisture-test before quoting.
• Attic insulation, ventilation, a soffit vent, and an attic fan all matter, since a roof deck that cannot dry stays wet under the coating.
• A vapor barrier keeps condensation out of the assembly, and coating over a roof that already traps moisture just hides the problem.
• Asphalt shingle, three-tab shingle, and architectural shingle roofs take a coating only while the mat is sound; curled or bare shingles need roof replacement.
• Wood shake and cedar shake need the gaps addressed first, or the film bridges and cracks on the first heat cycle.
• On slate, clay tile, and concrete tile, the work goes to the underlayment and flashing, since the tile itself already sheds water.
• Metal panel, standing-seam panel, and corrugated panel roofs get rusted fasteners sealed before the finish coat, never painted over.
• TPO, EPDM, and PVC membrane roofs get washed and primed, then coated while the sheet is still intact.
• Built-up roof, modified bitumen, tar, pitch, asphalt, and bitumen surfaces are the classic recoat candidates, as long as the felts are dry.
• Felt, roofing felt, and tar paper underlayment crumble once they dry out, and a coating has nothing left to grab.
• Synthetic underlayment goes on during a tear-off, because old felt wrinkles and splits in Phoenix heat.
• Ice-and-water shield and ice dam protection still earn their place in valleys and low-slope sections where wind-driven rain backs up.
• Drip edge, eave, rake, and verge metal keeps runoff off the fascia and soffit, and a missing drip edge is why fascia rots first.
• Ridge, ridge cap, and ridge vent get checked together so the attic still exhausts heat after the coating cures.
• Hip, gable, mansard, and gambrel shapes each change where water pools, so the coating spec changes with the shape.
• Valley, step flashing, counter-flashing, chimney flashing, and apron flashing are where most leaks begin, so each gets its own flashing bead.
• Pipe flashing, pipe boot, vent boot, and boot flashing crack under UV within a decade and are cheap to replace before coating.
• Chimney, skylight, and dormer curbs need a dedicated detail, because smearing coating over a joint never holds.
• Scupper, coping, parapet, and gutter edges get cleared and resealed so water leaves the rooftop instead of sitting on it.
• A clogged downspout backs water up to the eave, where it wicks back under the edge and into the wall.
• Purlin, batten, and counterbatten framing under a metal roof decides where the film has to flex.
• Overhang, canopy, and awning sections stay shaded and damp longer, so we schedule the cure window around them.
• Snow guard and anchor hardware comes off and goes back on so the film stays continuous.
• Sealant, caulk, adhesive, mastic, and roof cement each do a different job, and using the wrong one is why patches fail.
• Nail, fastener, and screw heads that have backed out get reset or replaced, since a proud head tears a coating from below.
• Waterproofing and weatherproofing come from the coating itself, while R-value has to come from insulation somewhere else.

Timelines, cost drivers, and site setup

Coating a typical low-slope roof takes one to three days once the surface is dry, and cure time before foot traffic depends on the product and the temperature. Cost moves with roof size, prep work, and which system you choose.

• Roof size and the roofing square count drive material cost more than anything else, and we measure instead of guessing from the driveway.
• Prep drives labor: replacing wet insulation, resetting fasteners, and rebuilding a parapet detail can cost more than the coating itself.
• Silicone and polyurethane systems cost more per square than acrylic, and they last longer over a roof that ponds.
• We set scaffold, ladder, and safety harness before anyone steps on the roof, because fall protection comes first on a two-story building.
• A pry bar, roofing shovel, and torch come out for detail work on modified bitumen, while a nail gun and air compressor handle repairs around vents.
• Debris and torn-off material leave in a dumpster the same day, and we rake the lot with a magnet before we pull out.
• A roof inspection is the first step of every roof estimate, Maricopa County building code sets the minimum for flashing and ventilation, and both the inspection and the estimate are free.
• Coating a roof that has reached end-of-life wear is money you will not get back, so we say so and quote roof repair instead. Call 602-533-0488 to book the survey.