Smoke shelf and smoke chamber repair in Lake Mary Jane

Refractory mortar and ASTM C199

ASTM C199 is the test method the code names for refractory mortars, the heat-rated mortars used inside fireboxes and smoke chambers. The code calls for parging made from mortar that conforms to it, and for firebrick linings laid in medium duty refractory mortar.

In practice, that means the product in a bucket on our job has been made and rated for fireplace heat. Ordinary masonry mortar is made for walls and weather. We name the refractory product we plan to use in the written estimate, so there is no question about what goes on your chamber walls.

Working from the flue down

Those directions begin the coat up high, beside the flue liner, and bring it down toward the damper. Beginning at the top keeps fresh material from dropping onto finished areas below.

Access decides how this happens in each fireplace. Some chambers let us reach the top through the damper opening, while others are easier from above. We explain the route your chamber allows before the job, and it is written into the plan.

Grit and mortar on the damper plate

Sand-like grit on the damper plate, or small mortar chips on the firebox floor after the damper is opened, point to joints letting go somewhere above. In the chamber, that often means old mortar or failed parging.

We look up from below to find the source, then reach it to test the area by hand. The repair depends on what we find, from repointing a few joints to a full new coat. Either way, the loose material is removed before anything new goes on.

What a chamber estimate lists

A clear chamber estimate separates the work into parts you can understand and approve one by one. Ours list preparation, masonry repair, the coat itself, the shelf and any damper, cap or firebox work beside it.

Each line has its own price, and the total does not change later without your approval. If cleaning uncovers something new, we stop and talk it through before adding anything.

• Cleaning and glaze removal
• Loose brick, joints and throat repair
• Refractory coat, walls and thickness
• Smoke shelf repair
• Related items on their own lines

What cannot be seen without opening the wall

A chamber inspection shows the inside surface and what can be reached from the damper and flue. It cannot show the full wall thickness, what lies behind an intact coat or the condition of framing inside nearby walls.

We say so in writing. If a finding suggests a hidden problem, we explain what further access would involve and what it would cost, and nothing is opened without your approval.