Fire cement – its uses and limitations

Fire Cement is a ready-to-use putty which is heat resistant up to 1250oc. There are a number of manufacturers and brands and it’s available in different sizes in both black and cream. The cement can be used to seal joints in wood stoves, especially around the area where the flue rises out of the top of the stove. It can also be used to repair firebricks. Fire cement when dry is a non-flexible solid sealant (unfortunately “high temperature” flexible silicone sealants degrade above 300 degree Centigrade which is above the normal operating temperature of your stove). The expansion and contraction of your metal stove as it heats up and cools down will inevitably crack any fire cement around joints on the flue and stove pipe.

Cracks in fire cement, or even where it has fallen out, are only a critical issue if smoke is coming through. Assuming your flue and stove are correctly installed and properly maintained, the negative pressure within the flue will draw smoke and fumes up your chimney, preventing any problems and any smoke coming out. But do remember to have your Carbon Monoxide alarm properly located and test it regularly; it provides an immediate warning of any problems.

It’s a routine and simple job to redo the joints with inexpensive fire cement (typically £2.50 for a small tub). First ensure the area is clean, free from dust and rust. To use, wear a latex glove and apply a liberal amount of cement on one finger. Then work the cement well into the cracked or damaged area. As soon as possible, gently heat dry the repaired surfaces, gradually raising the heat to full operating temperature over 3-4 hours. Apply further cement to any fire cracks that may appear.

Use straight from the tub! We always have stock of fire cement in our showroom.