I used High-Temp mortar for the exterior shell instead of stucco. Now, the mortar shell won't harden

I’m preparing to mount the stone veneer - but I’m concerned.

In Step 41 you mention that the “stucco is rock hard”…mine is not. Looking back to Step 40, you mention that we could use “stucco (or mortar mix)”. Since you sent many bags of “mortar mix” (see pics) and they had not been used up to that point…I assumed I was to use them for the “stucco shell”. I opened a bag, mixed in the water until it was a good consistency, and applied it to the wire mesh.

The shell that I made out of High-Temp mortar has not hardened.


You had High-Temperature mortar left over? Usually, customer get just enough…

High-Temperature mortar is a unique type of mortar that only hardens once it reaches a certain temperature. It’s different than standard Home Depot / Lowes type mortar.

But – since the mortar will harden once it reaches a certain temp – you need to start firing your oven to get the oven up to higher temps. Get it hot slowly – and over several days.

DO NOT RUSH the hardening / curing of the shell by firing the oven quickly… that will only break the oven.

I would definitely apply a layer of Stucco over the mortar shell (once you clean off any soot that gets on the oven from those curing fires).