How Chimney Flashing Protects Your Home

The flashing that wraps the base of your chimney is probably one of the most inconspicuous components of your chimney system. Yet when flashing is damaged or missing altogether, it can quickly become a very visible and critical issue.

Roofs and chimneys are separate structures with a gap between them. While this gap usually isn’t wide, it’s more than sufficient to allow water to run down through it. Preventing this intrusion is the job of chimney flashing.

Chimney Flashing Repair In Milford, NHWhat is chimney flashing?

Flashing is usually custom-made from sheet metal to properly fit around the base of your chimney. There are two layers: step flashing and counterflashing. Step flashing is L-shaped and installed to seal the roof/chimney gap by weaving it into the shingle courses. Counterflashing is then installed by embedding it into the chimney mortar joints and pulling it down to cover the top gap of the step flashing.

When installed correctly by an experienced chimney technician, flashing will effectively keep water from rain and melting snow out of your home.

Water damage from missing or defective flashing

Although you can’t see what’s below the roof/chimney gap, you can imagine what water will contact when it spills through. Intruding water can affect the roof, ceiling, wallboards, insulation, and the exterior of the chimney down inside the home.

Standing water against these materials will cause decomposition. Wood can start to rot and harbor mold growth; metal can rust and decompose; chimney bricks can begin decaying and lead to a dangerous structural compromise that could collapse the chimney or pave the way for a chimney fire.

Chimney flashing quickly becomes a critical component of your chimney system when you consider that early damage caused by a flashing problem is damage you can’t see – because it’s all happening within “invisible” areas of the home. By the time the problem becomes obvious, you can be looking at huge repair, restoration, and mold remediation bills.

Chimney damaged in Nashua, NHSolving the flashing issue

Fortunately, while flashing is a critical component, it’s also one of the easiest parts of a chimney system to fix and install. As a homeowner, you can perform annual or semiannual visual inspections of your chimney flashing, checking that it’s secure against the chimney and the roof and watching for signs of rusting and warping. Professional chimney inspectors also will take a close look at flashing each time they do an inspection.

(Flashing and all other chimney components including the masonry should be inspected by a CSIA-certified technician once a year). At one point, you’ll probably need to have your chimney flashing resealed or replaced. This is a fairly quick and inexpensive job that will be over before you know it and will possibly save you thousands on repair costs because of water damage. If your chimney flashing is in need of repair or you need new flashing, the experts at Black Moose Chimney & Stove of Antrim, NH, are ready to help.


We provide chimney repairs, component replacement, brickwork, chimney inspections, and chimney sweep services. Contact Southern New Hampshire’s chimney leaders at (603) 525-7905.

First Thing

John RantaJohn Ranta
17:01 22 Mar 24
They arrived on time, worked quickly and showed me the results. Prfessional throughout. jr
william greenwilliam green
23:21 14 Mar 24
Really helped me out can't say enough good things highly recommend!!!! The young man that came to my home was very knowledgeable and friendly great attitude all around answered all my questions and left me stress free best of all left no mess.🤙🏻🤙🏻
Michael Dell'OrtoMichael Dell'Orto
18:39 14 Mar 24
Jaime ConleyJaime Conley
17:13 14 Mar 24
Sarah GilliattSarah Gilliatt
01:46 13 Mar 24
A very thorough and careful job done! Thank you.
Larry CookLarry Cook
15:11 07 Mar 24
I wanted to give 5 stars but they are very busy which meant I had a good wait for both the inspection/cleaning, then for a quote on repairs and then for the repairs. Their prices seemed a little high to me but I have nothing to compare with as they were highly recommended by someone I trust and other companies had plenty of negatives reviews which kept me from getting additional quotes. I am happy with the work and they promptly returned to fix a mistake that had been made. Chris the inspector, Jennifer in the office, and Alex and his repair crew were all pleasant and took the time to answer all of my questions. Alex and his crew even took their shoes off (it was winter) before entering my house without even being asked! So if you are not in a rush and want to ensure you chimney is as safe as possible then I think you'll be happy with Black Moose.
Rebecca DeFuscoRebecca DeFusco
22:35 21 Feb 24
After a recent sweep of our chimney, it was discovered that our flue tiles were cracked. Black Moose techs were hard working, detail oriented and professional! Nice jobs guys! See you next year for my cleaning!
Karen CKaren C
14:52 14 Feb 24
Excellent I highly recommend Black Moose Chimney and Stove; Kelly and Liam are awesome, they did a great job. Extremely professional, arrived early, went through everything with a fine tooth comb ensuring pellet stove was thoroughly cleaned. They also were respectful of my home, conscientious and cleaned up after themselves. Made sure stove worked prior to leaving and told me to call promptly if anything came up afterward. Will definitely use them again.
Denise ClarkDenise Clark
16:32 31 Jan 24
We've had Black Moose clean our chimney for a number of years.But recently, we had an emergency situation at our home involving our chimney & oil furnace flue, which was caked full of soot from a malfunctioning furnace. They came & cleaned out both flues in no time, even going up on the roof with snow on it! They cleaned up after their work in the interior rooms where the oil furnace and the woodstove are located. Great work. Reasonable prices. Very nice people. You can't go wrong with Black Moose.
Joe GJoe G
18:30 24 Jan 24
Goods: The technicians know their business, very efficient in cleaning/inspection along with cleaning up after the 'dirty work'.Others: Communications could be more effective. Despite early coordination about scope of work (multiple flues within same chimney) the estimate provided did not reflect this and the final invoice was significantly more than the estimate provided.Quote for follow-on chimney relining was significantly more than that offered by other companies in the area (and far more than neighbors experienced for similar work accomplished by other companies)