Chimney Caps for Snow, Rain and Squirrels

A surprising number of older chimneys in Minneapolis and St. Paul have no cap at all. The flue tile sticks out of the crown, open to the sky. Rain falls straight down it, snow fills the top and melts into the smoke shelf, and squirrels and birds treat it as a hollow tree. Water in the flue mixes with soot and creosote and is one of the most common reasons a fireplace smells in damp weather.

A cap is a metal hood with mesh sides that bolts or clamps to the top of the flue. It blocks most falling water and keeps animals out, while letting smoke out freely. The current Minnesota Residential Code says a rain cap or spark arrestor must leave a net free area at least four times the flue outlet's (IRC R1003.9.2–.3), so it cannot choke the draft.

Signs you need this

• You can see open flue tile from the yard
• Scratching or chirping in the chimney in spring
• Water or rust in the firebox after rain
• A musty or sooty smell on humid days
• Leaves, twigs or nest material on the smoke shelf

How we do it

1. Check the top, freeWe look at the flue, the crown and any existing cap and measure the flue for a correct fit.
2. Clear the flue firstIf animals or a nest are inside, they come out before the cap goes on, priced at the inspection.
3. Fit the right capSingle-flue caps clamp to the tile; caps for liners attach to the liner's top plate; multi-flue chimneys can take one cap over the whole crown.
4. Secure it for windFasteners are tightened and checked so a cap can't lift off in a storm.

Cap or crown: what's the difference

The words get mixed up because the code calls the concrete top of a masonry chimney a cap. In trade language, that slab is the crown, and IRC R1003.9.1 says it has to be concrete, metal or stone, sloped to shed water, with a drip edge and a caulked bond break around the flue liner. The metal hood over the flue is the chimney cap or rain cap. Both keep water out, and a cracked crown under a new cap still leaks, so we check both.

Which cap fits which chimney

Most single clay flues take a stainless or galvanized clamp-on cap. A chimney with a new metal liner gets a cap made to attach to that liner. A chimney with two or three flues side by side, common in old houses where the fireplace, furnace and water heater each had their own, can take one larger cap that covers the whole crown. In a historic district, copper or a low-profile design may suit the house better, and we help you prepare photos and a scope if city preservation staff want to see it.

• Cap installed: typically $200 to $850 (national 2026 guides)
• Stainless single-flue cap: typically $475 to $600
• Animal or nest removal before capping: priced at the inspection

Snow and caps in a Minnesota winter

MSP averages 51.2 inches of snow a year on NOAA's 1991–2020 normals, and wet spring snow can pack the mesh of a fine-screened cap. We size the mesh and the cap height so it sheds snow and keeps clear airflow. If a gas appliance vents through the flue, a blocked cap is a safety problem, and the cap has to suit the appliance it serves.