How do I keep my chimney from leaking?

Keep a chimney from leaking by keeping its four water barriers sound: the flashing at the roofline, the crown on top, the mortar joints and brick, and a cap over the flue. The practical routine is a yearly professional inspection plus a look after major storms, with small defects repaired before they let water in. The work happens on the roof and the stack, so it belongs to a licensed pro, but you can do the watching from the ground.

Inspect every year

EPA says fire officials recommend getting your wood-burning appliance, chimney, and vent professionally inspected each year, and that this includes looking for any chimney cracks.^[1] Ask the inspector to report on the whole outside of the stack, not only the flue: flashing, crown, joints, brick faces and cap, with photos.

The USDA Forest Service advises that flashings should be checked twice a year when the roof is inspected and the gutters are cleaned.^[2] It also warns that many apparent roof leaks are really flashing leaks,^[2] so a chimney check that skips the flashing misses the likeliest failure.

What a sound chimney has

Woodstock Soapstone, a stove maker, lists what a masonry chimney should have. Two items matter most for water:

• Crown: a crown of concrete or non-water soluble refractory cement sloping away from the chimney and sealed with a flexible material.^[3] The slope is there to shed rain.
• Cap: a cap to keep out moisture, birds, or other pests.^[3] Caps also keep rain from running down the flue. See what a chimney cap does.

Add to that tight flashing, solid mortar joints and brick faces that are not flaking. If any of these is missing or worn, that is where the next leak will start.

What to watch for from the ground

You do not need to climb to catch most early warnings:

• Cracks or a flat, crumbling edge in the crown, which binoculars can show.
• White powder, flaking brick or dark damp patches on the stack.
• Gaps or lifted metal where the chimney meets the roof.
• Rust on the damper, water in the firebox or a damp smell in the fireplace.
• New brown stains on ceilings or walls next to the chimney.

Look after heavy rain, ice and wind storms. Photograph anything odd and book an inspection rather than waiting for the next downpour.

Keep gutters and nearby roof in order

The Forest Service pairs the flashing check with cleaning the gutters,^[2] so schedule both together and let the roofer or gutter contractor do the roof-level part.

If a leak has already started

EPA says that if wet or damp materials or areas are dried 24-48 hours after a leak or spill happens, in most cases mold will not grow.^[4] Dry the inside quickly, then see why water leaks around a chimney to work out where it is coming from.

When to call a licensed pro

For every repair. Re-pointing mortar, rebuilding or recoating a crown, replacing flashing and fitting a cap all mean roof access and work on the stack, and a repair in the wrong place can hide the real entry point. Roofing and masonry are separate licensed trades in Virginia. "Masonry contracting" means the service that includes the installation of brick, concrete block, stone, marble, slate, or other units and products common to the masonry industry, including mortarless type masonry products."^[5] The rule adds that this includes tuck pointing, mortar washing and parging.^[5]

DPOR says that if the work is valued at $1,000 or more, a valid Virginia Contractor's License is required for the license category in which the contractor is to work.^[6] Check the licence, and compare at least three written quotes. Our guide to who to hire for a chimney leak explains roofers versus masons, and what a liner is helps if the flue itself is cracked. Browse chimney answers or chimney and fireplace services.

Describe your chimney and licensed local businesses quote the inspection or repair.