Floor inside dome installation

[GianniFocaccia]

Re: Floor inside dome installation

Thanks for the reply. Would you suggest one 2" layer of insulation board or two?

As much as you can afford. I went with 2" of board on top of 3.5" of vermiculite. Another inch of board wouldn't have hurt.

[TropicalCoasting]

Re: Floor inside dome installation

I too cut my floor to fit inside the oven.
My logic was anything extending under the dome bricks and outside them was just more thermal mass, and would therefore have to be heated and insulated while serving no real purpose.
Why burn the extra wood and spend the additional time firing?

Wouldn't the floor under the dome just be part of the dome height?
I think of the whole thing as a floating igloo insulated top and bottom and a gap between dome and entrance.
The only advantage I can see in cutting out the floor and leaving it separate is for future repairs.
Has anyone had to do this?

[NCMan]

Re: Floor inside dome installation

In my opinion, it's all the same. As long as the floor bricks don't extend too far away from the dome and the insulation goes around them, it's all the same. And except for the tiny bit that a few would extend out, that is not more mass to heat. It's the same either way.

[SevenAcre]

Re: Floor inside dome installation

True, I guess it all just depends on how far out past the dome your floor bricks would extend, and how you've designed your build. I was going to write a whole long post showing the math for the added additional mass, then realized that really only applied to my particular build. I ran a 3/4 soldier course outside the floor. Had I placed them on top, everything would have changed. Let's just say it would have really messed me up, and my head already hurts just thinking about it.
-j

[NCMan]

Re: Floor inside dome installation

I agree, to some extent. There are applications where, depending on your build method, you may be adding extra mass. But on a traditional one, I feel it's just not worth all that effort to cut the bricks to fit inside. There are no real advantages. My 2? only.

[david s]

Re: Floor inside dome installation

Replacing floor bricks (if ever) is far easier if they don't have a dome sitting on top of them.

[tonybaker]

Re: Floor inside dome installation

at the end of the day, a fast heat up is what is most important?
If you have a massive construction it's going to take forever to get hot, and ok it will stay hot for longer, but who wants to cook for hours after the show is over?

For the dome go for perlite bricks if you can find them, They are soft and easy to cut and reflect heat down onto ordinary fire bricks set in the base.

I run my oven with a small fire off to one side, with a bed of cinders glowing nicely, I can cook for as long as I want just by throwing in a few sticks.

My main observation of the posts on this forum is that things get over complicated, keep it simple! If you want something smart to impress the neighbours, you can easily pretty up the outside of the dome with whatever you want.

By the way, I can place my hand on the outside of my dome regardless of inside temperature. Insulation is 4 ins. Perlite/cement render with another 1 inch ordinary masons render to make it waterproof.

[david s]

Re: Floor inside dome installation

at the end of the day, a fast heat up is what is most important?
If you have a massive construction it's going to take forever to get hot, and ok it will stay hot for longer, but who wants to cook for hours after the show is over?

For the dome go for perlite bricks if you can find them, They are soft and easy to cut and reflect heat down onto ordinary fire bricks set in the base.

I run my oven with a small fire off to one side, with a bed of cinders glowing nicely, I can cook for as long as I want just by throwing in a few sticks.

My main observation of the posts on this forum is that things get over complicated, keep it simple! If you want something smart to impress the neighbours, you can easily pretty up the outside of the dome with whatever you want.

By the way, I can place my hand on the outside of my dome regardless of inside temperature. Insulation is 4 ins. Perlite/cement render with another 1 inch ordinary masons render to make it waterproof.

The general consensus from most members is that you need thermal mass if you want to do any retained heat cooking (roasts and baking). Most oven builders find that they want their ovens to do more than just pizza.Generally there is insufficient thermal mass in the floor alone for this so the extra thermal mass required is in the dome. If using insulating fire bricks in the dome, although easier to cut they are also way weaker and will be subject to abrasion damage, particularly at the base of the dome and at the entry.Also an insulating brick will take longer for the heat to penetrate it and saturate it with the heat applied.

Ultimately your oven design is like boat design. It needs to fulfill how you want to use it and that often means a series of compromises.

[NCMan]

Re: Floor inside dome installation

Replacing floor bricks (if ever) is far easier if they don't have a dome sitting on top of them.

This is true. For those WFO builders contemplating the possibility of having to replace floor bricks that sit under their walls, they may want to go another route.

[rand18m]

Re: Floor inside dome installation

From what I can see the only advantage is if you needed to replace floor or portions of. I'm not sure what would bring that about, especially if building with new high quality bricks. I'm not against floor inside dome and may decide to go that route, I just haven't seen where ultimately it matters all that much and noticed most of the pics in the instruction pdf were not inside floors. Anyway I appreciate all responses, I will be starting my first oven soon. ;-)

[GianniFocaccia]

Re: Floor inside dome installation

and noticed most of the pics in the instruction pdf were not inside floors.

This may be true, but the FB oven plans provide a basic blueprint aimed at beginners. There are many examples of ovens here where adventurous builders implemented improvements that take the oven to the next level.