Oven base options

[apjenkins]

I have built the structure to support the oven and the concrete slab is now set and ready for the next stage. I have done some reading around and I've seen a lot of different options for the actual base of the oven.

I am trying to find firebricks, but I am also looking to make this build as cheap as possible. I wondered if I could use solid engineering clay bricks as the base? I have found a supplier of new bricks which are uniform, with nice tight edges, so I think they will make a good base for the pizzas. However, I am not sure how well they will perform? Will they hold heat, last a long time etc.

I know that firebricks are the better option, and may have to go with them despite the cost, but if I could use these bricks it would be great.


They are standard brick size, red clay, completely solid and classed as engineering bricks.


Any advice would be great.

[oblertone]

Im sure the engineering bricks will make a fine cooking surface but unless you've built insulation into the base slab, or are intent on putting some under the floor then you could be making a fundamental mistake. Whatever floor you use must be insulated otherwise you'll be trying to heat the slab as well as the bricks, which could take a while. There are a number of ways of doing this, the simplest is to use a board product such as vermiculite board, or Cal-Sil; the advantage being that you have a firm level surface on which to lay your floor. You can also use vermicrete which is a mixture of vermiculite and cement, but this will need time to dry out before you cover it.

Storage heater blocks are another alternative floor, and they can be a LOT cheaper than engineering bricks.

[downunderdave]

Jun 11, 2017 15:59:49 GMT oblertone said:

"Im sure the engineering bricks will make a fine cooking surface..."


i'm not so sure they would be suitable. I've seen plenty of old fireplaces with badly spalled hearth bricks. Engineering bricks are fired to a higher temperature but that does not necessarily make them more refractory. It is the composition of the clay used that determines their suitability and you will probably not be able to find out that information. There is a reason fire bricks are made and that is to withstand the thermal shock and high temperature they'll be subjected to. They may we'll be ok and after a year show no sign of deterioration, but it could be a different story 20 years down the track. If you do use them, lay them loose inside the dome so replacement later is an option.

[apjenkins]

Thanks for the info. I will use the engineering bricks and keep them loose. I am happy to replace in a few years.
I was looking at insulation board, to stop the concrete slab sucking all the heat, but wondered about bedding the bricks on ceramic blankets? Or would that not give a smooth enough base to work with?
Also, the internal size of the oven is 700mm, and I have guestimated an oven door that is 200mm tall, 350mm wide and 250mm deep, as I am quite tight for space. Do those measurements sound like a good combination? I can't really extend the internal oven size, bit could alter the door.
Cheers
A

[oblertone]

The door opening is about right in relation to the internal width (approx half) but the door height has a functional relationship to the inner dome height of roughly 63%. If you inner dome height is 350mm then your door could go up to 220mm; this 'magic' ratio allows good heat transfer from the products of combustion into the dome mass.

If you place bricks on ceramic blanket, you'll just end up with a thin compressed layer that won't do much insulating; use board.