Laying first course confusion

[tazzmacd]

I have been reading for a while now and have a question. It seems that in some builds the first course of soldier tiles are being put on the insulated Fiber board or the insulated slab next to the cooking floor. Other builds have the first course of 1/2 bricks are put directly on the cooking floor. In a couple of threads I have read that the idea is to keep a small space in the floor tiles so they can expand next to the first course of tiles and do not cement those to the cooking floor. Other threads are cementing them to the cooking floor.

Can I get some help to clear up the different approaches and why the difference? Pros and Cons of each approach?

Thanks

Pat

[david s]

Dome on top of floor: pros, faster because you don't need to make the perimeter cuts of the floor bricks too accurate, you can keep them really rough because they'll be covered. Cons, the mortar joint (if you have one) between the floor and the base of the dome is subject to abrasion from metal peels and other oven tools. Almost impossible to remove a floor brick that sits under the dome.

Floor bricks inside the dome : pros, Easier to replace perimeter floor bricks. You can have an expansion gap between floor and dome. Metal peel will hit dome soldier brick not joint at floor level. Cons, you need to make really precise cuts of floor bricks at their perimeter which takes ages, as does creating expansion gap.