Henry #1 Choice of Professionals: Repairing and Preventing Roof Leaks

Inspect for cracks, splits, tears, or any visible problems. Any you see will most likely leak.
Inspect all roof penetrations (skylights, chimneys, roof vents, etc.), to see if cement still adheres. Run a key or pen down a vertical surface. See if cement comes away from the surface. Any separation indicates a roof leak. Remember 8 out of 10 roof leaks occur at a vertical penetration of the roof.
Check all places where dissimilar materials come together—where metal meets brick, shingles meet metal, etc. These surfaces expand and contract at different rates, and therefore tend to pull away from each other. Check for tight seals. A loose seal might indicate your leak.
If all else fails, try locating the leak from the inside. Take a strong flashlight into the attic, and try following the leak uphill. Odds are, it will originate at some roof penetration. This will indicate your leak area.

Choosing the Best Product to Stop Your Leak

For metal roofs, or for the longest lasting patch:

In dry conditions, Henry 209 Elastomastic® (super rubberized) is the most durable, and the only choice for metal roofs, motor homes, mobile homes, modified roll roofing, and areas where dissimilar roof materials come together.

For cold and wet conditions that need immediate attention:

Choose Henry 208® Wet Patch®. Use Henry 208r® (rubberized) if you live in an area where the temperature fluctuates more than 50° through the year, or you have days over 100°F.

For dry weather conditions:

Choose Henry 204® Plastic Roof Cement . Use Henry 505 FlashMaster™ if you live in an area where the temperature fluctuates more than 50° through the year, or you have days over 100°F.

Patching fabrics:

Henry 181 Asphalt Saturated Glass Fabric or Henry 183 Yellow Resin Coated Glass Fabric

Repairing Your Roof Leak

Surface preparation:

Use a brush to clean away all dirt, dust, gravel, and any other loose particles. Wire brush metal to remove rust and scale. Cut away old roof cement if it prevents a smooth patch.

To repair metal flashing leaks:

Apply a layer of roof cement between adjoining materials.
Trowel a second layer of cement across the top of the flashing and work to a feathered edge to allow for drainage.

To repair asphalt or fiberglass shingle leaks:

Apply a small dab of roof cement under the shingle tabs.
If nails are missing, replace and trowel cement over flush nail heads.

To repair a hairline split or separation on a flat or low slope roof:

Trowel a 1/4" layer of roof cement into and around repair area, running 2" up and 2" out of any vertical leak, or 2" past either end of a leak on a flat surface.
Reinforce patch with a minimum of one ply of patching fabric completely embedded in the roof cement.
Apply another 1/4" application of cement over the top. Feather the edges so they are smooth, and water can run off the patch.

To repair blisters on a flat or low slope roof:

Cut raised area in an “X.” If moisture is found, let dry before proceeding.
Trowel roof cement into open area and reattach the cut sections.
Apply another coating of roof cement over the area and extending 6" beyond the “X” cut on all sides.
Embed patching fabric over the area into the roof cement. Apply another coating of roof cement, extending 2" over the patch in all directions, and embed a second ply of patching fabric. Apply final coating of roof cement, extending 2" on all sides.

Recommended tools: