Most homeowners never give a second thought to the flashing on roofs until water begins to leak into the house.  Some homeowners don't realize the flashing can be the cause of water leaks, many think its the roof itself. Many times that's not the case, the repairs are more simple than a roof tear off and replacement. Gaps and holes in flashing also give dirt, debris and insects an entrance to your home.

What is Roof Flashing

Roof flashing is used on roofs to close gaps between roof vents and the roof, chimneys and the roof and as protection from rain, snow and other weather conditions. Water seeping into a home through the roof can lead to wood rot, mildew and toxic mold growth which is why it is very important to make sure the flashing on your roof is always in good condition. Roof flashing can be made of various metals such as aluminum or copper. When these metals come in contact with a different type of metal either on a roof or touching a vent, a chemical reaction, known as a galvanic reaction, occurs and degrades both metals. Always make sure to use like metals on a roof. Roof flashing can also be made of layered tar paper or a special felt paper. Over time regardless of what your roof flashing is made from it can cracks, break and separate from roof vents and chimneys which will allow water to stream into your home.

Repairing Flashing

Clean around the areas of your roof where roof flashing is in obvious disrepair such as around skylights, roof vents or chimneys. Use a short whisk broom to clear away dirt and debris.

While you are on the roof, look around for any other damaged roof flashing. Even if cracks, gaps or chips are tiny, they need to be repaired because they will continue to get bigger. Even tiny, splits, gaps and damage to roof flashing can cause a water problem in a house.

Buy roofing cement at a roofing supply store, hardware store or home improvement store.

Roof Flashing

Spread a thick layer of roofing cement onto any cracks or chips and press the roofing cement into the cracks, gaps and splits. If you have a caulking gun, fill the cracks and chips with roofing sealer and forcefully press it into the damaged areas with a putty knife or trowel.

For larger gaps, splits, holes or pieces of roofing flashing that are missing, a simple patching job will not work, the roofing flashing will need to be replaced. Using roofing cement may work temporarily, but will not last.

Apply another layer of roofing cement over the entire repaired area.

Spread the roofing cement out past the edge of the roofing flashing with a metal putty knife or trowel. Make the edges of the roofing cement or sealer thinner and thinner, which is called feathering,  until you blend the roofing cement in with the roofing material.

Use a trowel or metal putty knife to smooth out the roofing cement, as you go towards the edges of the roofing flashing expand the area so the roofing cement goes 3 to 4 inches past the flashing.

Press firmly create a strong seal.


Examine the flashing on the roof seasonally.

Address issues as they arise.

Don't wait for the damage to become worse before making repairs.

Replace severely damaged flashing rather tahn trying to repair it.

Don't attempt to repair flashing if it is raining or snowing. You may slip and fall from the roof.