Video · Leaks & repairs
Stopping a Roof Leak with Henry Wet Patch
- Mod bit
- Built-up
- Rolled
- Metal
What this video shows
Henry's own walkthrough of its Wet Patch line, the rubberized asphalt cements you can push into a leak even when the roof is wet. Start here if water is coming in right now and you need a stopgap that holds until the roof can be fixed properly.
Key points
- Wet Patch is made to bond to damp or wet asphalt surfaces, which is why it's the go-to for a leak in the middle of a rainy stretch.
- Clear loose granules, debris and standing water off the spot first. It sticks to a wet roof, not to mud and gravel.
- Spread it about 1/8 in. thick and well past the damage with feathered edges. Henry's data sheet calls for fabric on any hole wider than 1/4 in. or longer than 2 in.
- It's for asphalt-type roofs (mod bit, built-up, rolled) and metal, not EPDM rubber or PVC.
- Treat it as a patch, not a roof: mark the spot and plan a permanent repair or recoat.
Products in this video
The products used or shown, or the closest match we could verify. Typical price ranges, not live prices.
Wet-or-dry roof cement · $20–$40
HenryHenry 208R Rubberized Wet Patch Roof Cement (HE208R042)
- Chemistry
- Asphalt
- Size
- 0.90 gal (1-gal can)
- Coverage
- About 12.5 sq ft per gallon at 1/8 in. thick
- Mod bit
- Built-up
- Rolled
- Metal
The emergency patch to keep in the garage: a rubberized asphalt cement that bonds to wet surfaces, even in the rain. Trowel it on thick and wide, and bed polyester fabric in it over anything bigger than a nail hole.
Read the fine print: Asphalt-based. Henry says to wait 30 days before coating over it, and it can bleed through white acrylic or silicone, so prime it with a bleed blocker or cut it out before a recoat. Not for EPDM rubber or PVC sheet roofs. Henry wants fabric on any hole wider than 1/4 in. or longer than 2 in.
Best for: Stopping an active leak on a mod-bit, built-up, rolled or metal roof
Check price on Amazon for Henry 208R Rubberized Wet Patch Roof Cement (HE208R042) (opens in new tab)Affiliate link — we may earn a commission at no extra cost to you. Coverage and specs are the manufacturer's stated figures. Disclosure
Wet-or-dry roof cement (caulk tube) · $7–$15
HenryHenry 208R Wet Patch Roof Cement, 11 oz cartridge
- Chemistry
- Asphalt
- Size
- 11 oz cartridge
- Mod bit
- Built-up
- Rolled
- Metal
The same wet-patch cement in a caulk tube, for nail holes, small splits and flashing edges where a trowel is overkill.
Read the fine print: Same asphalt limits as the can: let it cure before any coating, and don't use it on EPDM or PVC. A bead over a split is a stopgap, not a seam repair.
Best for: Pinholes, fastener heads and flashing edges
Check price on Amazon for Henry 208R Wet Patch Roof Cement, 11 oz cartridge (opens in new tab)Affiliate link — we may earn a commission at no extra cost to you. Coverage and specs are the manufacturer's stated figures. Disclosure
Polyester reinforcing fabric · $15–$35
HenryHenry 296 Polyester Repair Fabric, 4 in. x 150 ft
- Chemistry
- Other
- Size
- 4 in. x 150 ft
- Mod bit
- Built-up
- Rolled
- Metal
- Spray foam
- Acrylic-coated
- Silicone-coated
Thin, stretchy polyester you bed into roof cement or coating to bridge cracks, seams and flashing joints. It's the difference between a patch that splits in a month and one that lasts.
Read the fine print: Fabric goes into a wet base layer and must be fully covered by a top layer. Exposed fabric wicks water and breaks down in the sun.
Best for: Reinforcing patches, seams and flashing transitions
Check price on Amazon for Henry 296 Polyester Repair Fabric, 4 in. x 150 ft (opens in new tab)Affiliate link — we may earn a commission at no extra cost to you. Coverage and specs are the manufacturer's stated figures. Disclosure
Margin trowel · $10–$20
MarshalltownMarshalltown Margin Trowel, 5 x 2 in.
- Mod bit
- Built-up
- Rolled
- Metal
Small enough to scoop roof cement out of the can and work it into tight spots around flashing, and stiff enough to spread it 1/8 inch thick.
Read the fine print: Asphalt cement doesn't wash off with water. Keep mineral spirits and rags on hand for cleanup.
Best for: Applying roof cement and wet patch
Check price on Amazon for Marshalltown Margin Trowel, 5 x 2 in. (opens in new tab)Affiliate link — we may earn a commission at no extra cost to you. Coverage and specs are the manufacturer's stated figures. Disclosure
Putty knife / scraper · $7–$14
HydeHyde Stiff Putty Knife, 3 in. (01440)
- Mod bit
- Built-up
- Rolled
- TPO
- PVC
- EPDM
- Spray foam
- Metal
- Silicone-coated
- Acrylic-coated
A stiff stainless blade for scraping off failed caulk, lifting loose coating and feathering patch edges.
Read the fine print: Don't pry at sound membrane laps, or you'll open the seam you're trying to protect.
Best for: Scraping failed sealant and feathering patch edges
Check price on Amazon for Hyde Stiff Putty Knife, 3 in. (01440) (opens in new tab)Affiliate link — we may earn a commission at no extra cost to you. Coverage and specs are the manufacturer's stated figures. Disclosure
Read the full guide
Leaks & repairs How to patch a flat roof leak On an asphalt-based flat roof (modified bitumen, built-up or roll roofing), a rubberized wet-patch cement such as Henry 208R can be troweled on even in the rain to stop a leak today. The lasting repair is a fabric-reinforced three-course patch, or on EPDM, TPO and PVC a patch of matching membrane, because asphalt cement damages rubber and PVC and ruins TPO for future welding. If you plan to coat later, Henry says to wait 30 days over its wet patch, and white coatings may need a bleed-blocking primer.Video by Henry Company, embedded from YouTube. The summary, key points and cautions on this page are our own; Henry Company doesn't endorse TheFlatRoofPro.com or the products listed. Roofing work for hire generally requires a licensed roofing contractor.