Inside mortar joints

So… I was trying not to mortar the joint to the foam, but in doing so left large gaps on the inside of the oven. I have read some posts that say do not fill and others that say it is okay to use the rutland fire mortar product to fill the gaps. Any advice!!!

Hi Laurie, and welcome to the BrickWood forums.

There are two stages to consider: before you have fire in the oven, and after.

Before you light any kind of fire in your oven, you could fill the gaps in the front with the Rutland product. It looks like they are all pretty superficial, judging from the good mortar placement visible in the end bricks. I’d not worry about anything further back in the oven than the chimney cutout. The high temp fill will not cure until you start firing the oven, so don’t worry if it looks soft or not the right color.

After you fire the oven, it’s more work. You’d have to remove any soot (and there will be soot) before placing the material. On the other hand, the uneven color and most of the imperfections in the mortar will be thoroughly covered by that soot. (And never try to use the wet high temp mortar for this purpose. It will not adhere and eventually will fall at the worst possible moment into the worst possible place: your food.)

My advice is do the area from the chimney cutout forward. For joints further back, it’s only worth it if you can see daylight through those joints. I actually have one of those on a vertical joint in the first course of my rear wall. Easily fixed.

Hope this helps!