Skip to content

Thermocrete Q & A

Thermocrete® is a premium, durable ceramic liner for use in the repair, restoration and energy conversion of chimneys and chimney flues. Thermocrete seals holes and cracks, increases efficiency, and strengthens the chimney. Thermocrete makes it easy to retrofit chimneys for conversion to natural gas.

1. Can any chimney professional use Thermocrete Ceramic Flue Liner?

Thermocrete Ceramic Flue Liner can only be installed by a factory-trained technician. All installers are required to attend a comprehensive Thermocrete training program. After successfully completing the training, they receive official certification, assuring you that they are an authorized Thermocrete installer. Paramount/Rite-Way Masonry is the only authorized installer of Thermocrete in the state of Oregon.

2. Can Thermocrete repair a chimney-fire damaged tile liner? What are the limitations?

Yes, Thermocrete does repair heat-damaged clay tile. It fills cracks, binds tile together, closes eroded tile joints, and provides a heat-diffusing barrier that renders the total liner better than it was when it was first installed. Tests show that a Thermocrete-repaired broken tile liner is gas-tight, remains intact during normal (sub-1200F) use, and is 99% less likely to re-crack during elevated chimney-fire temperatures of 1200-2100F.

3. Has Thermocrete passed any official tests or certifications? What about U.L.? 

Yes. Thermocrete has undergone extensive testing by Ceram Research and Warnock Hersey / Intertek Testing Services. It was originally listed to the applicable sections of UL 1777 by Warnock Hersey in 1999 (#J99001572-231) then reevaluated, listed and labeled by Guardian Fire Testing Laboratories in 2011 to UL 1777 and ULC S 635 as a liner for Gas and Oil(GL90811/FI19311).

4. How will Thermocrete stand up to brushing during chimney cleaning, especially with flat-wire brushes?

Thermocrete stands up very well to normal chimney cleaning. No special care is needed during cleaning.

5. How does installation of Thermocrete work in cold weather?

The problems you may encounter in cold weather are primarily related to the application process, not the finished product. Whenever you are dealing with water in below-freezing conditions, there are precautionary measures that need to be taken, however, if done properly, Thermocrete can be sprayed in weather as cold as 20 F.

One of the benefits of Thermocrete is that a few minutes after the end of spraying, many heating appliances can be fired to complete the cure, with no worries about plummeting nighttime temperatures.

6. What about creosote wicking through tile liner cracks and remaining a hazard on the backside of existing tile?

Actually, the quantity of creosote that works its way through small tile cracks is inconsequential. We have never seen a dangerous quantity of creosote on the backside of minimally cracked tile. With a liberal coating of Thermocrete in place, hot gases cannot penetrate the repaired tile to reach any creosote film. Thermocrete provides a heat-diffusing barrier to minimize temperature rise on the back side.

7. How about eroded and spalled tile liners serving oil and gas appliances?

Thermocrete is excellent in this situation. Since Thermocrete is only as good as the substrate it is applied to, you should brush and peel away all loose liner materials first. The liner should generally remain, at minimum; 3/8″ thick at most spots. Any holes should be backed closely by masonry walls or filled with refractory materials. The Thermocrete coating will then strengthen and bind together the old surface with a new acid-resistant and moisture-resistant seal.