DIY Projects

How to Repair Leaking Chimney Roof Flashing

By: Danny Lipford

Roof flashing around chimneys can separate from the brick, allowing rainwater to leak inside the house. To repair loose roof chimney flashing:

  1. Clean any leaves or other debris out of the gap between the flashing and chimney.
  2. Use a chisel to remove any hardened roofing cement.
  3. Apply a generous amount of roofing cement behind the flashing.
  4. Use masonry nails or screws to reattach the flashing tight against the chimney.
  5. Cover any exposed nail or screw heads with roofing cement.
  6. Apply roofing cement to the joint between the flashing and brick.
  7. Smooth the roofing cement out with a paint stirrer or putty knife.

Watch this video to find out more.

Further Information

Video Transcript

The ā€œLā€ shaped flashing that protects the joint between a roof and a chimney can sometimes pull away from the chimney, especially if it’s only held in place by roofing cement. Begin correcting the problem by removing any leaves or debris from the void, and then scraping or chiseling the dried roofing cement off of the bricks so the flashing will lay flat against them.

Now, apply a generous amount of new roofing cement to the bricks behind the flashing an inch or so below the top of the flashing. Use masonry screws or nails to hold the flashing tight against the bricks before you apply more roofing cement along the top edge of the flashing.

Finally, smooth out the cement with a putty knife, and apply cement to the heads of all the fasteners.


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3 Comments on “How to Repair Leaking Chimney Roof Flashing”

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  • Walter Berry Says:
    September 5th, 2018 at 6:44 pm

    I spent all day patching the top of the chimney wel a little rain it came back in the inside wall where the shingles meet the chimney , the water is setting there and under the shingles, I think this is where the water is coming in, I am not a roofer but a little common sense go’s a long way’s, I am 66 years old and this is not my first time on the horse.

  • Heba ElGawish Says:
    June 29th, 2017 at 8:50 am

    How do I get up on the roof in a safe way??

  • Dave Reingold Says:
    April 18th, 2017 at 5:22 pm

    Gus and Grandpa:

    In much of California cement tile roofs abut a wood framework around the chimney, which is in reality, is a flu pipe in a wood box. I would assume that the process is much the same when the flashing pulls away from a brick chimney.

    I can see that at least one piece of roof tile has slipped about six inches and a dam has been created where debris and dirt has built up. There has been well over 20 inches of rain this rainy season, and water has collected here and made its way over the flashing, or through a fastener hole and has damaged about eight panels of plasterboard. I can also see where mold or mildew has begun to show as well.

    Can you offer suggestions as to how to go about inspecting a tile roof and how to choose to replace or repair broken tiles, especially those along the ridge line?

    Since we are renters, we’ll leave it to the property manager to have the actual repairs made. But knowing that he may ask his totally incompetent handyman to make the repairs, I want to be able to insist upon a roofer doing things correctly the first time.

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How to Repair Leaking Chimney Roof Flashing