Roof coating: what to know

What the job involves, what changes the price, and what to ask a pro.

What roof coating is

Roof coating puts a liquid layer over a cleaned and repaired low-slope roof. The coating reflects sunlight, seals small cracks and can extend the life of a membrane that is still sound. People look at coating when the roof is aging but not torn, or when they want a cooler roof surface.

Signs you need it

  • A chalky, faded or dull membrane surface that looks worn but is not torn
  • Fine cracks and hairline splits across the field of the roof, not large open seams
  • Fine surface crazing on a membrane that is still firmly bonded and dry underneath
  • Rising attic heat in summer on a flat or low-slope roof with an older membrane
  • A roof that passes a visual check with no active leaks but shows aging across the whole surface

What the pro does

  • Check the roof for leaks, open seams, failed flashing and standing water before any coating is applied
  • Clean the surface to remove dirt, algae, oils and loose coating, since coating will not bond to dirty or wet surfaces
  • Repair cracks, open seams, blisters and flashing, and let the repairs cure before coating over them
  • Apply the coating in the number of coats and the thickness the manufacturer specifies, with a roller or sprayer and attention to weather
  • Check the coating amount or film thickness as the work goes, and document the finished roof with photos

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Roof area and the number of penetrations, drains and details to seal
  • Membrane type and coating type, since each has different surface and bonding needs
  • Repairs needed before coating, including blisters, seams and flashing replacement
  • Surface prep, such as pressure washing, degreasing or primer on a dirty or previously coated roof
  • Number of coats and the coating thickness the product requires
  • Access, roof height, and any staging or lift needed for materials
  • Weather window and the season when the application can be done safely

What a written quote should spell out

  • Coating type, manufacturer, number of coats and the thickness each coat requires
  • Surface prep steps, including the cleaning method and drying time
  • Repairs listed by location, such as seams, cracks, penetrations and flashing
  • Drain and scupper clearing, included or shown as its own line
  • Warranty terms for the coating, including what the manufacturer requires to keep it valid
  • How the coating amount or film thickness is checked and documented

Questions to ask before you hire

  • Is my roof a membrane the coating is designed for, and can you confirm compatibility in writing?
  • How do you clean and prep the surface before coating?
  • How many coats do you apply, and how do you check the coating thickness?
  • Which repairs are needed before coating, and are they in the quote?
  • What weather does the coating need, and what do you do when rain interrupts the work?
  • Can you show me a recent coating job on a membrane like mine?
  • What warranty does the coating carry, and what does it require from me as the owner?

Red flags

  • A coating offered over a roof with active leaks or open seams that have not been repaired
  • No surface prep described, or a claim that the roof can be coated without cleaning
  • A coating the manufacturer does not list for the membrane on the roof
  • A promise that the coating will last with no warranty terms or maintenance plan
  • Application planned in rain or onto a damp surface

What you can do yourself

You can safely clear leaves from gutters and drains you reach from the ground, and watch the ceilings below for leaks before a coating is considered. Coating means climbing onto a roof, handling heavy material and working with solvent-based products, so leave it to a pro. Call a pro once you suspect open seams or active leaks, or the membrane is blistering.

Licenses and permits

Roof coating is commonly done by licensed roofing contractors, and repair or reroofing work can need a permit. Check your state and local licensing and building office requirements before you start.

Roof coating questions

Can any flat roof be coated?

No. The coating must suit the membrane and the surface condition. A pro should confirm compatibility with the manufacturer before the work starts.

Does a coating stop leaks?

A coating can seal small cracks and fine splits, but it does not repair a failed seam or flashing. Repairs come first.

How often does a coating need to be redone?

It depends on the product, the climate and the surface condition. Ask the manufacturer for the recoat interval and have the roof checked during the warranty period.

Will a coating make the roof cooler?

Reflective coatings can reduce heat gain at the roof surface. The effect inside your home depends on the roof, the attic and the climate, so ask the pro what to expect in your attic.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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