Insulation

[Hatt000674]

Hi I have 2 x 50mm ceramic boards and only need one for the layout of my oven. Can I double them up so I have 100mm of insulation on the base. Also what's the best thing to use to bind them to the concrete base and to each other. thanks for the help

[Gulf]

Hi Hatt,

Welcome to the forum. Yes, you can stack one board on top of another. The weight of the brick will hold the insulation in place. No need for bonding, Just stagger the joints between the layers. The dimensions of your ceramic fiber boards must be very large for just one to cover the entire footprint of an oven?

[Hatt000674]

Hi gulf
yeah they are 1000mmx1200mm. Was going to make it 1000mm in diameter

[UtahBeehiver]

Is 1000mm the ID of the oven? If so, the dome walls will not be insulated. It is very important that all parts of the oven, ie dome wall, floor, etc, do not touch the concrete hearth. If the dome wall extend down to the hearth, the hearth acts a heat sink robbing precious BTUs from the oven and affecting the oven's ability to maintain and store heat. I suggest you download, read, and study the free/cheap e-plans from Forno Bravo website to help you with the design. Although dated, it is a good baseline for builders. Plus one on Gulf's comments.

[Hatt000674]

The 1000mm is the external of the dome so the base fire bricks will be sat on top of this then the dome on tope of these. Will be full oven bricks chopped in half to make the dome so it will roughly have an 800mm internal diameter of the dome. I'm just trying to find out if putting 2 of the 50mm insulation boards on top of each other will have any adverse effect. I'm thinking if anything it should surely be a positive.
I'm planning on having 100mm ceramic board then 64mm oven brick as the pizza oven floor. Then the external dome to have a 25mm-50mm insulation blanket then possibly a perlite render to follow and normal render after that.
Thanks Dan

[UtahBeehiver]

Okay, two layers of CaSi is great floor insulation, but 25mm (min. 50mm is recommended) of ceramic blanket is on the light side but if you pcrete it with 10-1 then you are good. Do you have compression specs on the floor insulation. Recommended 75 PSI at 5% compression. There are some softer CaSi out there. Also CaSi will absorb water readily, need to raise of hearth with ceramic tiles and install weep holes. Again, get the cheap or free eplans.

[Hatt000674]

These are the ceramic boards. I've ordered 25mm fire blanket but suspect I might have enough to do 2 layers.