Chimney flue tile repair for Cypress Springs homeowners

The flue, the liner and why the words get mixed up

The flue is the passage smoke and combustion gases travel through on their way out of the house. The liner is the material that forms the walls of that passage, most often clay tile in a masonry chimney, sometimes a metal or cast-in-place lining added later.

People use the two words for the same thing, and repair offers blur them further. When we write up a flue repair, we name the passage, the lining material and the exact section that is damaged, so you know whether you are paying to fix part of the existing lining or to put in a new one.

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

Factory-built chimneys are a different system

Factory-built fireplaces use metal chimney sections rather than a masonry flue. The Florida residential code, in Section R1005.1, says factory-built chimneys shall be listed and labeled and installed and terminated according to the maker's instructions.

Repairs to those chimneys use parts from the same listed system. We identify the system from its labels where they can be read and explain what can and cannot be repaired within its listing. Mixing parts from different makers, or using generic pipe in a listed system, can put it outside its listing. When the right parts are no longer available, replacing the chimney system may be the only compliant choice, and we explain that plainly.

Mortar crumbs in the firebox

Small crumbs of mortar on the smoke shelf or in the firebox usually come from joints somewhere above. They can come from the flue joints, the smoke chamber or the firebox itself.

We find where the crumbs are coming from before recommending a repair. Joint repair in the flue and repairs lower down are different jobs, priced separately. Joint erosion in the flue shows up as open gaps between tiles when seen from above or below. Crumbling in the firebox shows up at the brick joints you can touch. The findings name which one you have.