What is the best roof leak sealer: spray, coating or tape?
Short answer. For a sloped shingle roof, no spray, roll-on or tape sealer is a good long-term leak fix; they are emergency stopgaps, and coating a shingle roof can trap moisture and cause warranty problems. Liquid rubber and elastomeric coatings do their best work on low-slope roofs, metal roofs and some flashings, while leaks on shingle roofs are fixed by replacing the failed boot, flashing or shingles.
The main types of sealer
- Spray-on rubber: aerosol cans that leave a rubbery film. Handy on a small hole in a gutter seam or metal flashing, but on shingles the film peels as granules shed beneath it.
- Liquid rubber and elastomeric coatings: rolled or brushed on. Built for low-slope roofs, metal roofs and some flashings, where they can extend life over a clean, sound surface.
- Silicone roof coatings: excellent UV resistance on low-slope roofs, but very little sticks to silicone later, which complicates future repairs.
- Patch tapes: butyl or rubberized asphalt with a UV-resistant face. Fast in an emergency, but they let go on hot, granular shingle surfaces.
- Fibered roof cement: the classic trowel-grade patch. Cheap and effective for a while on small holes.
Why coatings and shingles do not mix
Asphalt shingles shed water through overlapping courses; they are not meant to be sealed shut. A coating can block the paths water uses to drain, trap moisture under the film, and leave the roof looking patched. Shingle manufacturers generally do not approve field-applied coatings, so read the warranty before trying one.
When a sealer is the right choice
- A temporary patch to stop water until a roofer arrives.
- A low-slope porch or flat section, using a compatible coating system over a sound surface.
- Metal roof seams, fastener heads and gutter joints, using products made for metal.
Then fix it properly
On a shingle roof, a permanent leak repair means new flashing, boots or shingles installed in the right lap order. See common roof leak causes and metal roofing in Georgia.