Chimney repair in Cottage Grove, MN
Most chimney repairs come down to one thing: keeping water out. We fix crowns, caps, flashing, mortar joints, dampers and flue liners, and we tell you which repairs can wait and which cannot.
Common chimney repairs, from the top down
Chimney cap
A metal cap with a screen keeps rain, snow, leaves and animals out of the flue. Missing or rusted caps are one of the cheapest problems to fix and one of the most common causes of water inside the chimney.
Crown
The concrete slab on top of a brick chimney sheds water away from the brick. Small cracks can be sealed. A crown that is crumbling or was built flat with mortar usually needs to be rebuilt.
Flashing
Metal flashing seals the gap between the chimney and the roof. When it lifts or the sealant fails, water shows up as a stain on the ceiling or wall next to the chimney.
Mortar joints and brick
Water that soaks into brick freezes and pushes the face off (spalling) and washes out mortar. Tuckpointing replaces the worn mortar before bricks loosen.
Damper
A damper that is stuck, warped or rusted shut lets heat escape all winter or keeps smoke in the room. Top-sealing dampers are an option for older fireplaces.
Flue liner
Cracked clay tiles or a liner that does not fit a new appliance can be relined, usually with a stainless steel liner sized to the stove, insert or water heater.
Why Cottage Grove chimneys need these repairs
Cottage Grove's first neighborhoods went up in the late 1950s, and the city grew from about 800 people in 1950 to more than 13,000 by 1970. A brick chimney from that era has been through more than 60 Minnesota winters. Every freeze and thaw works water a little deeper into the crown and the top courses of brick, which is why the top of the chimney usually fails first.
The second common story is a change of appliance. When an older home gets a high-efficiency furnace with its own plastic vent, the water heater may be left venting alone into a clay flue sized for both. A flue that is too large drafts poorly and lets exhaust cool and condense on the way up, which wears the tiles and mortar from the inside. Relining with a properly sized liner is the usual fix.
Repair or rebuild?
We start with the smallest repair that solves the problem. A cap or a sealed crown crack costs far less than a rebuild, and it is often enough. When brick is loose near the top, or the flue tiles are cracked through, we explain why a bigger repair is needed and what happens if you wait.
Signs your chimney needs repair
- Water stains on the ceiling or wall next to the chimney
- Brick pieces or crumbled mortar on the roof or the ground
- White staining (efflorescence) on the brick
- Rust on the damper or firebox
- A cap that is missing, bent or rusted through
Chimney repair questions
Why is my chimney leaking only when it rains hard?
Heavy, wind-driven rain finds gaps that light rain does not: lifted flashing, a cracked crown or a missing cap. A leak that shows up after snow melts often points to the crown or the flashing on the uphill side of the chimney.
Can a cracked chimney crown be repaired, or does it need replacing?
Hairline cracks in a sound crown can be sealed with a crown coating. A crown that is crumbling, loose, or was built flat with mortar instead of a sloped concrete cap usually needs to be rebuilt.
What does tuckpointing involve?
Tuckpointing means grinding out worn mortar to a set depth and packing in new mortar that matches the old one in strength and color. It keeps water from getting behind the brick, which is what loosens bricks over time.
Do I need a new liner for a wood stove insert?
An insert vented into a large masonry flue usually needs a liner sized to the insert's outlet so it drafts properly and can be swept. Check the insert's installation manual for the manufacturer's venting requirements.
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Related: chimney inspection and chimney sweeping.