Hello from Billericay Essex

[enkindle]

Hi All,



Firstly, thanks for the brilliant forum with so many inspiring builds and great advice on offer. I’ve been reading and researching my WFO build for over a year and finally found time to make a start. I’m going for a Pompeii build with a 28” diameter cooking floor which should be large enough for 2 pizzas or a large roasting dish. Ideally I would like to go a bit bigger but my available space pretty much restricts me to this size.



So, to the first of what’s likely to be many questions. A friend donated 70 insulating fire bricks which I’m planning to use to give a 115 mm thick insulation layer between the supporting slab and the oven floor Firebricks. I think they will have a lower thermal conductivity then a vermicrete base of the same thickness and won’t need so much drying time but I’m wondering if this will be sufficient under floor insulation or should I also be adding a layer of Calcium Silicate board? If an additional board is recommended should I install this between the slab and the insulating bricks or between the insulating bricks and the floor firebricks?



Thanks in advance for any help and ideas,

Paul.

[simonh]

on my build I had the slab, then the board, then then firebricks. That has served me pretty well. How thick a board are you planning to use? from memory mines was 50mm.

Simon

[downunderdave]

115 mm of IFB is plenty IMO and more would be overkill. Remember that it is subject to the law of diminishing returns. 100 mm of 5:1 vermicrete is considered the standard and your IFB’s would beat that in both thickness and insulating value. Most builders don’t use them because of cost, but free is the best price.

[enkindle]

Thanks for the replies. I was considering adding 25 mm of Calcium Silicate board but it did feel a bit of an overkill so I’ll stick with the 115 mm of Insulating Firebricks. I have my base and slab built and just waiting for it to fully harden before starting on the floor and then the fun stuff with the dome build.