Oak Frame Question

[manmakingoven]

Hi,

I have built a base for my oven using green oak sleepers, but I now want to make the dome a little larger than I had originally intended: an internal diameter of 3 feet.  This will mean that in places the bricks I am using to make the dome over the oak frame.  Is this oak or will the oak get too hot.  Should I cut the oak back so I can insulate it, and if so, with what?

[oblertone]

You've done such a great job on the base, it'd be a real shame to watch it smoulder which it definitely will if you leave the dome bricks in contact. What is the driver for a larger oven ? The speed at which these cook pizza means you are constantly moving just one, so room for two is just inviting trouble.

[downunderdave]

You haven't left yourself enough room for insulation around the dome as it is now. It is also much better if the floor bricks don't extend out past the outside diameter of the dome base, or heat is lost via conduction. The whole oven should be encapsulated in insulation.

[manmakingoven]

Thanks to you both for your thoughts. Oblertone - I decided to make it bigger because it just didn't look like it was going to be big enough when I made a former - there was barely going to be room for the pizzas let alone the fire. Dave, what you say makes perfect sense. I just had the bricks and thought it would be easier to lay the whole thing.

So supposing I remove some bricks (they are sitting on sand and bottles as an insulation layer btw) and cut into the wood and cast a doughnut of insulating concrete, made with vermiculite. I know this is all a bit back to front, but it shouldn't take too long.

I have sort of combined a few ideas from different sites but for the dome I am mostly following the Forno Bravo plans.

[oblertone]

My oven (see build thread below) is 32" internal diameter and works perfectly well for pizza, bread and roasting; when cooking pizza the embers are pushed into the sides and there is plenty of room for any size pizza (remember door width) and as I said above, I only manage one at a time. A larger oven will take more fuel to heat and you'll still be doing one at a time.

In your situation I'd remove the beautiful herringbone floor you've created, cut back the oak to half current width and at least 2" deep then lay a vermicrete insulating layer to the top of your frame. Lay out a soldier course on that leaving enough room for insulation and render, then re-lay your herringbone inside that before building the dome. Your dome insulation should contact the floor insulation for best effect. The important thing is to encapsulate your dome with insulation otherwise you will leach heat out to your combustible frame.

Paul