Repairing Cracks in a Masonry Heater Facing -

Cheryl B <cherylb@gmail.com>

Good morning,
We had a masonry heater installed about eight years ago and when heating it for the first time we warmed it just a bit too quickly. Nothing catastrophic happened but now we are wanting to repoint the cracks. I can’t seem to find the paperwork that indicated the proper morter mix for the stone facing. I know it had more sand than just straight from the bag. Could you perhaps either send me the info or tell me where to find it?

Thank you,

Cheryl B

Forestport, NY

Hi Cheryl:

The mortar mix could be over a wide range, there is no standard mix. Regular Type N mortar would probably be the closest to the average. It is available at building supply stores as a dry premix in a 50 lb bag, labelled “mortar mix”, or “mortar mix, type N”. Type S would be too strong.

Here is an alternative procedure: Heat the heater up hot, so that the cracks open up to their widest. Wedge them in the open position with metal wedges, for example cut nails or horseshoe nails etc.

When the heater is cool, very carefully caulk the cracks with G.E. Type 1 Clear Silicone (available at Home Depot, smells like vinegar). Immediately, before the silicone skins over, dust the surface with dry mortar mix powder. The powder will embed in the surface of the silicone, giving the appearance of a regular mortar joint, but providing a permanently flexible joint.

Best …………. Norbert Senf