Last updated: October 2026. Written by the In-Ex Designs Roofing team.
The short answer: what to use on a leaking asphalt shingle roof
For a small, active leak on asphalt shingles, the right product is an asphalt-based roof cement or roof sealant that meets ASTM D4586, the standard for asphalt roof cement. Several are labeled for wet or dry surfaces, which matters when you are patching right after a monsoon storm. DAP’s Roof Waterproof Asphalt Sealant, for example, is listed for “repairing minor roof leaks” and “spotting shingle tabs,” can go on wet or dry surfaces, and meets ASTM D4586 Type 1. Rust-Oleum’s Advanced Wet or Dry Roof Repair is an asphalt roof cement sold for the same jobs on shingled roofs.
Sealant is a stopgap for small cracks, lifted tabs, exposed nail heads and gaps around vents. It will not fix missing shingles, cracked or rusted flashing, or a worn-out roof, and a leak that shows up as a ceiling stain or other warning sign is usually a symptom of something a tube of sealant can’t reach. If you are not sure where the water is coming in, a professional inspection is cheaper than patching the wrong spot.
Why Phoenix is hard on shingles and on sealant
Valley roofs bake. Phoenix logged 70 days at or above 110°F in 2024, against a long-term average of roughly 21, according to the National Weather Service. That heat dries out the asphalt in shingles, weakens the factory seal strips and makes granules shed faster. Then the monsoon arrives with wind-driven rain that finds every lifted tab. A sealant here has to stay put in summer heat and keep its bond through big swings between afternoon and overnight temperatures, which is why product limits matter. Gardner’s Wet-R-Dri patch, for instance, lists an application range of 50°F to 120°F surface temperature, and a dark shingle roof in July can run well past that by midday. On Valley roofs, sealing work belongs in the early morning or in the cooler months.
Asphalt roof cement, silicone, polyurethane or acrylic?
Asphalt roof cement (ASTM D4586) is the default for shingle repairs because it is made from the same family of material as the shingle. It is what shingle manufacturers point to: Owens Corning’s technical bulletin on hand-sealing shingles calls for ASTM D4586-compliant asphalt roof cement, and GAF’s Matrix 203 plastic roof cement is listed for “sealing shingles” and for leaks around flashings, chimneys, vents and skylights. It comes in caulk tubes for small jobs and trowel-grade pails for flashing work.
Polyurethane and hybrid roof sealants are useful where shingles meet metal, such as vent boots, flashing edges and gutters, because they bond well to several materials and stay flexible. Check the label says it is suited to asphalt roofing before using it on the shingle itself.
Silicone resists UV and water very well and is the basis of many full roof coatings, but most silicones cannot be painted or covered with asphalt products later, and asphalt cement will not stick to cured silicone. If silicone goes on now, every future repair in that spot gets harder. Use it only where the product label says it is made for asphalt shingle roofs.
Acrylic products are mainly roof coatings for low-slope roofs rather than spot sealants for steep shingle roofs. If a shingle roof needs a whole-surface treatment, see our guide to the best roof coating for shingles.
How a proper sealant repair is done
The manufacturer data sheets agree on the basics. The surface has to be clean and sound, with loose granules, dirt and old caulk removed; on a wet surface, wipe off standing water first. GAF’s instructions for Matrix 203 call for working the cement into the crack at roughly 1/8 to 1/4 inch thick and spreading it about 2 to 4 inches beyond the damage. For anything wider than 1/4 inch or longer than 2 inches, they say to embed glass or polyester fabric in the cement and cover it with a second layer. DAP adds that joints should not exceed 3/8 inch wide and deep, and that you should not apply when rain is forecast within 24 hours.
When a lifted shingle is re-sealed, less is more. Owens Corning specifies four 1-inch dabs of roof cement under a laminated shingle, or two dabs under each tab of a three-tab shingle, about an inch from the edge, and warns that too much cement can blister the shingle. GAF’s bulletin says the same, suggesting quarter-sized dabs. Smearing a thick layer over the whole shingle traps heat and moisture and looks worse than the original problem.
When sealant is the wrong fix
Sealant makes sense for a handful of small defects on a roof that is otherwise in good shape. It is the wrong answer when shingles are missing or creased from wind, when the leak comes from flashing that has pulled away or rusted through, when granule loss has exposed the black mat across large areas, or when the roof is near the end of its life. In those cases the patch hides the problem until the next storm. Our roof warning signs guide for Phoenix homeowners covers what to look for on shingle, tile and flat roofs, and our leak guide covers what to do the moment water comes through.
Have In-Ex check it before you climb up
Walking a hot shingle roof is risky for you and for the shingles. In-Ex Designs Roofing serves Phoenix, the East and West Valley, Maricopa and the White Mountains. Call 602-938-7575 and we will find where the water is actually getting in and tell you whether a sealant repair will hold or whether something bigger is going on.
FAQs about roof sealant for asphalt shingles
What is the best roof sealant for a leak on asphalt shingles?
An asphalt-based roof cement or sealant that meets ASTM D4586, ideally one labeled for wet or dry surfaces if you are patching right after rain. It bonds to asphalt shingles, and it is the material shingle manufacturers specify for hand-sealing.
Can I use silicone caulk on asphalt shingles?
Only a silicone that is labeled for asphalt roofing. General silicone caulk is a poor choice because most silicones can’t be painted or covered with asphalt products later, which makes future repairs in that spot harder.
Can roof sealant be applied when the roof is wet?
Some products can. DAP’s asphalt sealant and Rust-Oleum’s Wet or Dry Roof Repair are both made for wet or dry surfaces. Wipe off standing water first, and read the label, because many sealants need a dry surface.
How hot is too hot to apply roof sealant in Phoenix?
Check the product’s surface-temperature range. One common roof patch lists 50°F to 120°F surface temperature, and dark shingles in a Phoenix summer can exceed that by late morning, so work early in the day or in cooler months.
How much sealant should I use under a lifted shingle?
Very little. Owens Corning calls for four 1-inch dabs under a laminated shingle or two under each three-tab tab, and warns that excess cement can blister shingles.
Is sealant a permanent fix for a roof leak?
No. It is a repair for small cracks, nail heads and lifted tabs. Leaks from damaged flashing, missing shingles or an aging roof need a proper repair, which an inspection will identify.
Sources
DAP Roof Waterproof Asphalt Sealant technical data sheet (images.dap.com); Rust-Oleum Advanced Wet or Dry Roof Repair product page (rustoleum.com); GAF Matrix 203 Plastic Roof Cement data sheet (documents.gaf.com); GAF Technical Bulletin TAB-R-115, High Nailing Shingles (documents.gaf.com); Owens Corning Cold Weather Shingle Installation Technical Bulletin; Gardner Wet-R-Dri All-Season Roof Patch technical data sheet (gardnercoatings.com); National Weather Service Phoenix, 2024 summer climate summary.
