Chimney Flashing

  • Chimney flashing consists of 2 types of flashing
  • Chimney flashing comes in 2 styles and a few different types of material that the flashing is made from.

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Chimney flashing being installed

Chimney flashing keeps water from running down the chimney and penetrating into the house. Flashing leaks can cause expensive damage to the interior of the house, so it is important that the flashing is present, has been installed correctly, and is in good condition.

Usually there are 2 sets of flashing- the chimney flashing and the roof flashing that butts up against the chimney and is covered by the chimney flashing.

Roof flashing up against a chimney

Roof flashing, inserted underneath roofing shingles. Butts up against the chimney.

The roof flashing is bent at a right angle and is inserted underneath the roofing shingles. This flashing will butt up against the chimney as the chimney is built up in height.

The chimney flashing is inserted into the mortar joints of the chimney, and it goes OVER the roof flashing that butts up against the chimney. Chimney flashing can be installed as “step” flashing or “linear” flashing. Flashing material can be made of metal, copper, or lead.

Step flashing

Linear Flashing

Bent chimney flashing can allow rain and driving rain to get in and run down the chimney, into the house. This can lead to stained and water-damaged ceilings and walls. Often times this can be repaired by tightening the flashing with sheet metal screws and the application of a high-quality caulking.

If you see this at your chimney flashing area:

A roofing cement compound (tar) has been tooled over the metal flashing of the chimney. This was an attempt to solve a leak. This is a red flag, and the flashing should be replaced. This is usually something that a homeowner has done, and is a temporary fix at best.

Chimney flashing can be rusted and look pretty bad, yet still be quite functional. At this point, the rust can be sanded and the flashing painted with Krylon metal paint to preserve the metal. We consider this inexpensive preventative maintenance. If the flashing is heavily corroded, then you want to have it replaced asap.

Chimney flashing should be inspected on a regular basis. This photo shows the intersections of flashing properly caulked so that water cannot get in. Often we find flashing that has been improperly caulked or not caulked at all! Cheap caulking can wear away. Something as stupid as this can, and has, caused thousands of dollars of damage.