A roof coating typically costs $1–$4 per sq ft nationally, against $4–$10 for a new TPO membrane, and a typical coating job runs $500–$2,000, according to HomeGuide. Spray foam roofing costs $3.50–$7.00 per sq ft and lasts 40–50 years. The first decision is whether the existing roof is sound enough to coat.
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What does a roof coating do, and what doesn’t it do?
A coating is a liquid-applied membrane rolled or sprayed over an existing low-slope or metal roof. It restores a roof that is ageing but still sound; it does not fix one that has failed.
- It can: seal small cracks and seams, add a new waterproof surface, reflect sun on white or light colors, and extend the roof’s life.
- It can’t: dry out wet insulation, repair a rotten deck, or stop leaks from flashing that hasn’t been fixed first.
If a roof has widespread wet insulation or deck damage, coating it only seals the water in. In that case, see TPO and flat roofing for replacement options.
Acrylic, silicone or polyurethane coating?
The chemistry decides where a coating works. CertainTeed, a coatings manufacturer, sums up the two most common types this way:
| Acrylic | Silicone | |
|---|---|---|
| Ponding water | Can break down faster under standing water | Holds up better where water stands |
| Best suited to | Sloped metal roofs with good drainage | Flat and low-slope roofs |
| Sun and surface | Slowly erodes at the surface over time, which keeps it cleaner but thins the film | Very UV-stable; tends to collect surface dirt |
| Cost | Usually cheaper to buy; may need more coats | Often fewer passes to reach the same thickness |
Polyurethane coatings are also used, often as a tough base coat. Whatever is quoted, ask for the product name and its manufacturer’s data sheet, which states the required thickness.
Can metal roofs be coated?
Yes, if the panels are still structurally sound. Coating a metal roof usually means treating rust, tightening or replacing fasteners, and sealing seams and laps before the coating goes on. It’s often used on older commercial and agricultural metal roofs. New metal roofing is covered on metal roofing.
What is spray polyurethane foam (SPF) roofing?
Spray foam roofing is sprayed on as a liquid that expands into a seamless, insulating layer, then covered with a protective coating. HomeGuide puts it at $3.50–$7.00 per sq ft installed with a 40–50 year lifespan.
- How it’s applied: the old roof is cleaned and prepared, foam is sprayed to the specified thickness, and a coating is applied on top.
- Why it always needs a coating: the foam isn’t made to sit in sunlight uncovered, so the top coat protects it and must be maintained.
- Recoating: the top coat is renewed over the roof’s life; ask for the manufacturer’s recoat schedule in writing.
- Where it fits: irregular low-slope roofs with many penetrations, and buildings that benefit from added insulation.
Spray foam is a specialist system that not every roofer installs. Ask to see foam roofs the crew has done and how they’ve aged.
Why is a moisture survey needed before coating?
Because coating over wet insulation traps the water. A moisture survey (infrared scan, capacitance meter or core cuts) maps wet areas, which are cut out and replaced before coating. Skip this step and the coating can fail early.
What should you ask about coating warranties?
- Is the warranty from the manufacturer, the contractor, or both?
- What thickness must be applied for the warranty to apply?
- Does it require recoats or inspections, and how often?
- What does it exclude: ponding areas, foot traffic, existing defects?
For commercial buildings and maintenance plans, see commercial roofing.
How it works with us
- Tell us about the roof. Fill in the short form once: the job, your ZIP code and how to reach you.
- A local roofer contacts you. Your request goes to a licensed and insured, local roofer in our network, who contacts you within 24 hours to set up a free inspection.
- You get a quote and decide. The inspection and quote are free, with no obligation. Check any roofer against our 5 checks before you sign.
Roofers Greenville is a free referral service. Roofing work is performed by independent contractors in our network. How our referral service works.
Areas we serve
- Greenville County core (within about 20 miles of Greenville): Greenville, Greer, Taylors, Mauldin, Simpsonville, Five Forks, Fountain Inn, Travelers Rest, Easley and Piedmont.
- Rest of the Upstate (about 25–40 miles): Anderson, Belton, Clemson, Seneca, Pickens, Spartanburg, Boiling Springs, Lyman, Moore, Campobello and Woodruff.
Every town, ZIP code and county we cover is on the service areas page.
Frequently asked questions
How long does a roof coating last?
HomeGuide doesn’t state a lifespan for coatings in general; it depends on the product and the thickness applied. The manufacturer’s warranty term for your exact product and thickness is the best guide.
Which coating is best for a roof with ponding water?
Silicone. CertainTeed rates it as more resistant to standing water than acrylic, which can deteriorate faster where water ponds. Fixing the drainage is still the better long-term answer.
Can a coating stop my flat roof from leaking?
Only if the leak sources are repaired first and the roof underneath is dry and sound. A coating over failed flashing or wet insulation won’t hold.
Is spray foam roofing worth it?
It can be on irregular low-slope roofs or buildings that need insulation, with a 40–50 year life according to HomeGuide, as long as the top coating is maintained. Get quotes for a single-ply membrane too, so you can compare.
Thinking about a coating? Request a free roof coating assessment.
Sources
- HomeGuide: Flat roof replacement cost (Nov 2025; coatings and spray foam)
- CertainTeed: Acrylics vs silicone
Last reviewed: October 2026. Roofers Greenville is a free referral service; roofing work is performed by independent contractors in our network.