How long does a flat roof coating last?

HomeGuide gives silicone 10 to 15 years and acrylic 7 to 20 years. Over an older roof, a FacilitiesNet guide expects about five years from a coating. HomeGuide also says flat roofs in rainy, sunny Southern climates need recoating every three to five years, so plan on recoats rather than one application.

Is coating a flat roof cheaper than replacing it?

Usually, if the roof qualifies. HomeGuide prices coatings at $1 to $4 a square foot against $3 to $11 to replace a flat roof. The saving only holds on a dry roof. FacilitiesNet's guidance is that a roof more than 25% wet should not be coated, because the trapped water stays under the new layer.

Can you coat a flat roof that is leaking?

Not as a fix. The leak has to be found and repaired, and the wet roofing dried out or replaced, before any coating goes on. FacilitiesNet says a wet roof should never be recoated. A moisture survey tells you how much of the roof is wet, and that decides whether coating is still an option.

Flat Roof Coating in Tallahassee, FL

Cost: most roof coatings install for $1 to $4 a square foot; silicone runs $1.50 to $4.50 and acrylic $0.50 to $3.00 (HomeGuide).
Life: HomeGuide gives silicone 10 to 15 years and acrylic 7 to 20; over an aged roof, a FacilitiesNet guide expects about five.
Upkeep: flat roofs in rainy, sunny Southern climates need recoating every three to five years (HomeGuide).
Test first: if a moisture survey finds more than 25% of the roof wet, coating it is wasted money (FacilitiesNet).

Tallahassee Expert Roofing turns your request into a call from a contractor who restores low-slope membrane and built-up roofs. A coating is a liquid layer rolled or sprayed over a roof that is still sound. It seals hairline cracks and reflects sun, but it can't dry out insulation that is already wet.

Flat Roof Coating Types

Florida's building code lists the standard each coating has to meet (FBC Building Table 1509.2). Ask for the product name and its standard in the quote.

Silicone

Silicone coatings meet ASTM D6694. HomeGuide credits them with reflecting up to 90% of UV and resisting leaks where water ponds. Silicone and urethane both hold up to ponding better than acrylic, which matters on dead-flat roofs after a summer storm. The downsides are that silicone picks up dirt and gets slippery when wet. Contractors charge 20% or more extra on sloped sections.

Roller applying a thick white elastomeric acrylic coating over a granulated modified bitumen roof

Acrylic (Elastomeric)

Acrylic coatings meet ASTM D6083 and are the cheapest option in HomeGuide's table. They suit hot, sunny places. HomeGuide also says they need temperatures above 50°F to cure, do poorly where rain is heavy and aren't ideal on flat roofs. On a well-drained modified bitumen roof, acrylic can make sense. On a roof that holds water for a day after rain, ask why the quote isn't silicone. HomeGuide recommends silicone or acrylic-elastomeric coatings for modified bitumen and EPDM.

Polyurethane and SPF Foam

Moisture-cured polyurethane (ASTM D6947) installs for $1.50 to $4.00 a square foot and handles foot traffic and impact well (HomeGuide). Spray polyurethane foam is a full roof system rather than a coating, at $2 to $6 a square foot. It needs a protective top coat within 2 to 72 hours of spraying (FBC Residential R905.14.3). HomeGuide puts foam recoats every five to seven years. Florida code lets a new coating go over an existing foam roof without a tear-off (FBC Building 1511.3).

Coat or Replace: Moisture Surveys and Core Samples

The deciding test is how wet the roof is underneath. FacilitiesNet's guidance is to get a moisture survey before you decide: a wet roof should never be recoated, and one more than 25% wet isn't worth coating. SquareDash adds that a core sample shows whether an existing commercial roof can take a recover at all. If the damage is only on the surface, coating or a membrane recover can work. Wet insulation or soft decking means that part comes out first (HomeGuide).

Roofer seen from behind fitting step flashing where a shingle roof meets a siding wall

Why Tallahassee homeowners call Tallahassee Expert Roofing

Your request reaches one roofer, never a call list
Homeowners pay nothing to use this line
Ask for the shingle wind class and Product Approval number in writing
The roofer's estimate is free and you're not obliged to hire

Flat Roof Coating: Which Roofs Qualify

A coating needs a roof that drains, is dry and is made of something the coating maker approves.

Built-up and modified bitumen
HomeGuide says most bitumen roofs take a silicone or acrylic-elastomeric coating. On a gravel-surfaced built-up roof, ask how the gravel is handled; the code bars reinstalling old aggregate (FBC Building 1511.5).
EPDM, TPO and PVC
EPDM is on HomeGuide's list for silicone or acrylic-elastomeric coatings. For any single-ply sheet, ask for the coating maker's written approval for that membrane.
Asphalt shingles
HomeGuide notes that the National Roofing Contractors Association advises against coating shingles. Florida code only allows it under the shingle maker's instructions (FBC Residential R908.3).
Drainage
New liquid-applied roofing needs a design slope of 1/4 inch per foot (FBC Building 1507.15), and a reroof that drains positively is exempt. Fix ponding with drains or tapered insulation before coating; flat roof repair lists the options.

A coating that is part of a larger repair or recover may need a permit, depending on scope. Roof replacement covers the City and Leon County offices. For whole commercial buildings, see commercial roofing.