Smoke shelf and smoke chamber repair in Apopka

What the smoke chamber does above the damper

A masonry fireplace has a wide firebox and a much narrower flue. The smoke chamber is the tapered space between them, rising from the throat and damper to the bottom of the flue. Smoke gathers there and is funneled upward.

Because it sits out of sight, the chamber is easy to forget until something falls onto the damper. Our pros treat it as its own part of the fireplace, with its own findings and its own line on the estimate.

• Collects smoke above the damper
• Narrows the passage toward the flue
• Carries the first flue tile at its top

Damper replacement as its own line

Chamber repair and damper replacement are often done on the same visit, but they are different jobs. A replacement throat damper, or a sealing damper mounted on the chimney top, gets its own description and price.

Keeping them apart lets you see what each part costs and decide in your own order. If the damper must come out to give access to the chamber, the estimate says so and explains how it will be reinstalled or replaced.

Masking the fireplace face and hearth

Cured coating is hard to remove. The data sheet we work from warns that once the material cures, it will damage any non-target surfaces, and it calls for inadvertent spray or spills to be cleaned at once with warm water and mild detergent.

That is why we mask the fireplace face, the surround and the hearth before mixing begins. Stone, tile and painted brick near the opening get extra care. Any splash is cleaned right away, before it has a chance to set.

Listed chamber coatings

The chamber coating data sheet we work from states that the product is listed to UL Subject 2505 and meets ASTM C199 as a medium duty refractory mortar. It also describes the product as meeting the IRC and NFPA 211 requirements for parging and smoothing corbelled smoke chamber walls.

A listed product comes with directions that were part of that listing, which is why we follow them closely. We name the product we plan to use in the estimate, so you can read its data sheet yourself if you like.

Refractory mortar and ordinary mortar

Masonry mortar for exterior walls and chimney joints is made to handle weather, and it is the right product there. Inside a smoke chamber, the exposure is heat, and the code calls for refractory mortar instead.

Mixing the two up leads to failures, such as ordinary mortar used to patch a chamber that crumbles after a season of fires. We use each where it belongs and name both in the estimate when a job involves inside and outside masonry.