Roof Coatings: When They Work

A coating is appropriate when

• The existing membrane is intact, adhered and not at end of life
• The insulation underneath is dry, verified by survey or core cut
• Drainage works — no areas of continuous ponding
• Details are sound, or are being properly reinforced with fabric as part of the work
• The goal is to extend service life and reduce heat gain, not to stop an active leak

A coating is the wrong answer when

• Insulation is wet — sealing water in destroys the R-value permanently and rots or rusts the deck
• Seams are failing across the field rather than at isolated points
• The roof ponds, since most coating warranties exclude ponded areas
• It is being sold as a cheaper alternative to a replacement the roof actually needs

Silicone or acrylic

Silicone handles ponding and weathering better and holds up in intense UV, which suits Sacramento summers. Acrylic costs less, recoats easily and breathes, but it is less tolerant of standing water.

Either way the roof must be cleaned properly and the details reinforced. Most coating failures are preparation failures, not product failures.

Common questions