DO NOT mortar the hearth / cooking surface fire brick together or to the floor!

Do not mortar the hearth firebrick together or to the floor - they need to be placed somewhat loosely together so they have room to expand when they reach 1200°+.

When they reach those high temps - they expand. If they are mortared in… well… somethings got to give. And It can easily be a firebrick.

Here is an example of what not to do - both on the floor… and on the firebrick on the side of the oven. Can you see another mistake the builder made? The answer is below the picture.

The firebrick on the sides and back of the oven should be staggered - NOT straight lines! If you got a hairline crack, it will run along the mortar joint. But if it was staggered, the crack would stop at the next brick it runs into.