Mortar on oven floor

My brother in law is building my oven and he put the bricks in and not the way I would have done it. In addition to orientation, he put mortar between the bricks. Do I need to start over from the base up?

Also, does he need to use mortar over the blanket before finishing the the outside of the oven or can he leave an “air gap” to help insulate?

Hi Jacob and welcome to the BrickWood forum.

Your BIL sounds like he believes he “knows better” than the instructions, am I right?

I’d like you to post a couple of photos showing us the specific area, but I can already deduce that you are talking about the hearth firebrick.

Yes, that does NOT get any mortar, and NO placing the brick in a linear (across or front-to-back orientation rather than in a herringbone pattern) is not okay. Two rookie mistakes in one area.

And “adding a air gap” is only going to weaken the stucco shell, so that would be a third. The mineral fiber insulation is very efficient without your BIL’s help. Or is he proposing to skip the stucco altogether and just brick over the mineral fiber?? Step away, BIL, step away. The stucco shell is the protective component that keeps the mineral fiber dry and forms the very air gap that he’s looking for. Altering that step will end in tears. Like this build (not quite the same thing, but it’s an example of what happens when even licensed contractors go rogue).

Your oven is not ruined, and it does not need to be torn apart to fix this, but it will require remediation. There is a procedure for this, thanks to another builder’s contractor who knew better than to follow instructions.

I’m sorry this happened, and I don’t say this very often, but your BIL screwed up.

Please instruct him, if you even want to let him near this project again, to follow the instructions rather than improvising and “improving.” There is a reason for each and every step, and the way it is laid out. The hearth will crack if it is mortared into place, and you will be frustrated beyond measure each and every time you try to slide a peel into the oven past a heaved brick.

Do send pictures, and let’s keep talking, Jacob!