How thick should the joints be when applying Heat Stop refractory mortar products?
A joint thickness of 1/16” to 1/8” is recommended for all Heat Stop refractory mortar products. If a thicker joint is required, we recommend the use of a dry mix - Heat Stop II or Heat Stop 50. For all of the refractory mortar products (Heat Stop Premix, Heat Stop II, Domestic Fireplace Mortar or Heat Stop 50), you will need approximately 50 lbs. of product to lay up 100 firebrick.