Can we use leftover high temp mortar for our outer stucco shell?

We have quite a bit of the firebrick mortar mix left. Is it okay to use this for the outside portion of the oven that goes over the fire blanket, or is it important to use regular mortar instead?


Yes, it is important to use regular (“Type S” or a mortar designed for stucco or an actual stucco mix) mortar on the outside. The cool part about the high temp mortar is that it does not fully cure until you fire it to high temperatures. That’s a problem for the shell, which has at least 2 layers of high performance mineral fiber between the outside and the firebrick. So it won’t cure and it won’t protect your oven.

The really good news is that regular stucco is very cheap in comparison to high temp mortar.

If you have one or more bags, you’ll find you can sell it on a service like Craig’s List for the same price you purchased it.

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