How to fix roof flashing

Roof flashing is one of the most important components of your roof. It is the thin material, typically galvanized steel, that is used to secure joints in areas that tend to receive a lot of water, such as valleys, dormers, chimneys, and skylights. When flashing becomes loose or broken, these vulnerable areas can succumb to water damage. Flashing essentially protects areas where the roof meets other structures.

Basics of Repairing Roof Flashing

If roof flashing damage is caught early enough, the repair is often minimal and inexpensive. For example, if the flashing on your roof has developed small holes from corrosion, holes up to ¾- in diameter can be patched using roofing cement and a patch of the same material of the flashing.

Repairing Small Holes

To repair small holes in roof flashing, roughen the material around the hole using sandpaper or a wire brush. This will allow the cement to better adhere. Next, clean the flashing to prepare it for repair. The patch should be cut slightly larger than the hole so that it overlaps on all sides. Once the flashing is prepared, the patch can be affixed to the flashing using roofing cement. Use extra roofing cement over top of the patch as an extra waterproofing measure.

Replacing Damaged Or Corroded Flashing

If the flashing has suffered extensive damage or is highly corroded, it will likely need to be replaced instead of repaired. This requires the removal of several rows of shingles to gain access to the base of the flashing. It is easy to damage the shingles while trying to remove them. Therefore, this project is best left up to the professionals.

Removing Old Mortar & Caulk

Replacing old flashing requires removing the old mortar and caulk that line the edges of the flashing. This can be tricky as the seals must carefully be chipped away to prevent damage to surrounding materials. Special masonry caulk can then be used to seal the joints between the new piece of flashing and the structure. The seam between the cap and step flashing must also be sealed using urethane roofing cement or some form of silicone caulking compound. Roofing cement should also be spread approximately six inches from the edge of the shingles and under their edges.

Reseal Drip Edging

How to Maintain Roof Flashing

Roof flashing damage can have many causes, such as when ice dams occur. However, following certain maintenance tips can help keep your flashing in good condition and help prevent leaks.

If you find that there are leaks in areas where the roof meets a structure, such as a chimney, deterioration of the metal roof flashing is usually to blame. Sometimes the metal simply rusts from exposure to the elements, and other times it becomes loose or can deteriorate from old age. Either way, old or damaged roof flashing can wreak havoc on your home.

Regular Roof Inspections

It is important to have your roof regularly inspected to determine the condition of the flashing. During inspection, the edges of the flashing will be closely examined to look for gaps that could allow water infiltration. The roofing cement should also be examined to determine if it is cracked or starting to crumble. In some cases, the flashing can be repaired by simply resealing it which is easier than patching. If you want new or repaired flashing to match the rest of your roof, you may need to paint it so that it looks cohesive.

Avoid Stepping On Flashing

Whenever you are working on your roof, it is important to avoid kneeling or stepping on the flashing. You also want to avoid putting a lot of pressure to any area that is within 12 inches of the flashing. This can put excess weight on the roofing materials which can cause damage to the joints and disturb the flashing.

Replacing Damaged Flashing Areas

Consult a Roof Repair Contractor

Many homeowners make the mistake of taking on their roof repairs themselves. When it comes to critical components of the roof, such as flashing, it is always best to leave this job to the professionals. If roof flashing is not installed properly, water can gradually sink beneath the material and into your home. You may not notice at first, but over time the damage will be evident. This will result in more costly repairs down the road.

Roof repair contractors also have more expensive repairing roofs. A contractor will know the right procedures and materials to use to ensure that the job is done properly and up to code. A roof repair contractor can also provide regular inspections to ensure that your roofing materials are in good condition and that there are no signs of damage that require attention.

Want to learn more about how to repair roof flashing or need assistance with flashing repair? Contact the Northern Virginia roof repair contractors at Beyond Exteriors today and schedule a roof inspection.

Q: Tim, I really need your help. My roof is leaking, and my last attempt to get it repaired was fruitless. It rained again and water still came in. Where do most roof leaks happen? Is it okay to use caulk or black roofing cement to do a roof repair? I just need you to help get me up to speed so I can talk with a roofing contractor. — Geri G., Sea Girt, N.J.

A: Most roof leaks happen in the same place as Geri’s. Based on my 40-plus years of clambering around on roofs, I’d estimate that well over 90 percent of roof leaks happen at flashings.

A roof flashing is a thing that stops water from coming into your home where something pops up through your roof. That something might be a chimney, a plumbing vent pipe, a powered attic fan, a turbine vent or a dormer, or it might be where two roof surfaces intersect.

You’ll also find roof flashings where a lower roof touches up against a taller wall of your home or a neighboring building like the condo next door or the walk-up next to your home.

Roof flashings can be made from thin metal, rubber, and a few other materials. Some flashings are built into products like a bathroom vent roof cap or the standard plumbing vent pipe flashing.

Flashings can be challenging for a rookie roofer. Some flashings are easy to install while others require considerable skill and an understanding of basic physics principles.

I prefer roof flashings made from metal that can be soldered. Copper, galvanized steel, lead and traditional tin-plated steel are examples of these fine materials.

Standard caulk and black roofing cement are not acceptable materials to use with flashings. The sun’s powerful ultraviolet (UV) light breaks down these materials in a few years. It’s okay to use caulk and roofing cement as a last resort to make a temporary leak repair, but don’t allow a roofer to convince you they’ll work for the long term.

I’ve got some nice photos and videos at my website showing you common roof flashings. These will help you select the best roofer to repair your roof. Visit go.askthebuilder.com/roofflashing.

Q: I’ve got a brick chimney, and a contractor told me the crown was crumbling and needs to be repaired. What is a chimney crown and what’s involved in the repair? — Gary N., Saginaw, Mich.

A: Chimneys are expensive to repair so you want to keep yours in excellent shape.

A chimney crown is the roof of a chimney. Just as the roof on your home keeps water from entering the center of your home, a chimney crown prevents water from soaking down into the core of the chimney.

Just about every chimney crown I've ever seen has been installed wrong. The best ones have a flashing membrane under the crown to capture any water that might leak through the crown material.

Crowns are supposed to overhang the chimney and have a drip kerf on the underside of the overhang. The crown material should be made using concrete that has a blend of hydrated lime, Portland cement and small pea-sized gravel.

Many bricklayers just use the regular mortar mix for the crown material and they taper it down to the edge of the last row of brick. This is a big mistake and the Brick Industry Association frowns on this poor practice.

The chimney crown should not touch up against the clay flue liners that are in the center of the chimney. These should be surrounded by a layer of foam so the flue liner can expand and contract without exerting pressure on the crown material. A special high-performance caulk that resists UV degradation fills the top 3/8 of an inch where the crown material is adjacent to the clay flue liners.

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