build dome on or around insulated base and firebrick floor?

[pmac]

A first time WFO builder....
I have base built and am about to start hearth and dome (400mm internal height) so just wanted some views on the following please:

I am considering using either Thermalite blocks or insulation board under the oven floor bricks -  what would be best and, if insulation board, which is best and from where?

Also, is it better to build around insulation and floor or on top? most builds I have looked at are on top but some books suggest around as you can easily replace floor.

Thanks

[awalker]

Around does seem to be stated a lot. So you can the 'easily' replace the floor.

From the wood fired oven says that as well. But he used his oven daily for commercial bread baking, for years. He only noticed slight degradation in fire bricks, only where he lit the fire in the same place every day. If I remember correctly.

So for normal use you will probably never need to replace the floor.

But admit I still laid mine so the main floor could be replaced. But built on top of the side bricks. But that is also a barrel oven so can still get to most of the floor.

[awalker]

Also not sure about thermalite block I used foamglass sheets. Great insulation, waterproof but produce s glass dust when you cut it.

[oblertone]

Regardless of the shape of your WFO it should ideally be encapsulated in insulation for best heat retention. Working to this principle should give you the answers you seek. As to a loose-laid floor, yes this might be a consideration in a commercial oven used daily, but most 'hobby' WFO's won't see anything like wear or cracking on the floor.