What the advisory covers
The Asphalt Roofing Manufacturers Association (ARMA) has published guidance advising against the field application of any coating or rejuvenator over installed asphalt shingles, a position echoed by many individual shingle manufacturers.
Coatings and rejuvenators are used on other roof types to boost solar reflectivity, resist biological growth, improve impact resistance, or extend service life. Asphalt shingles are a manufactured product, and field treatments can alter fire classification, algae resistance, and impact resistance.
Why manufacturers say no
Many asphalt shingle manufacturers specifically do not recommend field treatments on their products. State or local building codes may also prohibit the practice, since a field-applied coating or rejuvenator can alter performance characteristics of the roof assembly, including fire classification, algae resistance, and impact resistance.
Before any treatment is considered, the shingle manufacturer should be consulted. Local building and zoning authorities, and the homeowners association where applicable, should also be checked to confirm the application is allowed.
Reported problems after field treatment
ARMA documents several failure modes that have shown up on asphalt shingle roofs after a coating or rejuvenator was applied:
- Shrinkage of the coating material, which can cause unsightly curling or cupping of the shingles.
- Loosening of the granule surfacing on the asphalt shingles.
- Vapor retention when a non-permeable coating seals the voids around and between the shingles, potentially trapping moisture inside the roofing system.
ARMA notes that a non-permeable coating that seals those voids may contribute to moisture accumulation within the roofing system.
The claimed benefits, and the evidence gap
ARMA notes that few studies document how widely these coatings are used on asphalt shingles or how well they work.
Rejuvenators are a separate product category
Liquid-applied products marketed as rejuvenators are typically sprayed or rolled onto an asphalt shingle roof that has been in service for several years and may be showing normal signs of aging. They are treated the same way as other coatings for purposes of this advisory: most asphalt shingle manufacturers specifically recommend against applying a rejuvenator to their shingles.
What to do before any treatment
- Contact the asphalt shingle manufacturer to confirm whether a specific field treatment is acceptable for the shingles on the roof.
- Check with the local building and zoning department, and the homeowners association if one applies, to confirm the application is permitted.
Both checks matter because a field-applied treatment can change the performance characteristics of the roof, including its fire classification, algae resistance and impact resistance.
Aging shingles on the Grand Strand
If your asphalt shingle roof is showing its age, ARMA’s advice is to check with the shingle manufacturer and your local building department before any coating or rejuvenator goes on. Waccamaw Roofing provides roof inspections, roof repair and roof replacement across the Grand Strand, including Myrtle Beach, Conway, North Myrtle Beach, Murrells Inlet and Pawleys Island. Call (843) 488-4181.
FAQ
Can you put a coating on asphalt shingles after they are installed?
ARMA advises against it, and many asphalt shingle manufacturers specifically do not recommend field-applied coatings on their products. Local building codes may also prohibit the practice.
What happens if a coating is applied to asphalt shingles?
Reported problems include coating shrinkage that curls or cups the shingles, loosening of the granule surfacing, and moisture buildup if a non-permeable coating seals the voids around and between shingles.
Do rejuvenators actually extend the life of an asphalt shingle roof?
ARMA notes there is limited documentation showing that rejuvenators extend roof life, save energy, or repair leaks on asphalt shingles, while the risks of coating these shingles remain real.
This article summarizes reporting from asphaltroofing.org.