Chimney flue repair for South Lake Conway Villa homes

The kinds of lining the code accepts

For ordinary residential appliances, Section R1003.11.1 of the Florida residential code lists four acceptable flue lining systems. Any repair or replacement we propose has to leave your flue inside one of them.

When a proposed fix does not clearly land in one of these categories, we say so and explain what that means for using the fireplace.

• Clay flue lining complying with ASTM C315
• Listed and labeled chimney lining systems complying with UL 1777
• Factory-built chimneys, or chimney units, carrying a listing for use inside a masonry chimney
• Other approved materials that hold up against flue gases and condensate to 1,800 degrees F without corroding, eroding, softening or cracking

The mortar that belongs between flue tiles

Ordinary masonry mortar is not what the code asks for inside a flue. Section R1003.12 calls for clay flue liners to be laid in medium-duty, water-insoluble refractory mortar conforming to ASTM C199, a material made to handle heat and moisture inside the passage.

Older chimneys were not always built that way, so we check what the joints actually contain and how it has held up. Where we repair joints, the mortar or listed repair product is named in your estimate, together with the sections it goes into.

Where a stove pipe enters the chimney

Florida's residential code, in Section R1003.16, has connectors enter a masonry chimney through its side, inside a thimble of fireclay, rigid refractory or metal that holds the connector so it can neither pull loose nor stick past the liner wall.

Damage around the inlet is part of a flue assessment when an appliance connects there. A cracked thimble or a connector pushed into the flue affects both the draft and the lining. We check both and include any thimble repair in writing.

Big fires in a cold flue

A large, hot fire lit in a cold flue heats the tile quickly and unevenly. Sound tile usually copes. Tile that is already cracked or weakened may not.

After a repair, start with small fires and build up gradually, following any curing guidance for the repair product. We tell you what that looks like for your flue before we leave. Even a sound flue does better with a gradual start. A small fire warms the tile, the smoke chamber and the air in the flue together, which also helps the chimney begin drawing before the fire grows.