My first attempt for 42" oven / changed to 36"

[George_M]

How many days need to wait until fire again my oven when I finish perlcrete insulation ?
Also need to start again with small fires?
Thanks David..

[david s]

The surface of the blanket tends to be somewhat lumpy, but by covering it with a layer of vermicrete you can get back to a perfect spherical form. In addition the hardened vermicrete gives you a firm surface to render against. Depending on how much cement you use in the mix, but vermicrete is approx. half the insulation value as blanket.

[George_M]

David,
I knew that from the first day that this side will be difficult to add the insulation but i will succeed it.I want to have a round shape oven.

I have a general question: If i didn't put perlcrete and i could put ceramic blanket in 5 or 6 or more layers is it the same?Or the perlcrete has better insulation properties??
Why need to put perlcrete? Ceramic blanklet is easier to put than perlcrete for example.

[david s]

You now probably understand the advice I gave you in this post. The photo is not too clear (zoom in and look at the left hand side), but the oven is integrated to the corner by allowing the vermicrete to sit right against the wall.
#179
That space in the corner is pretty much useless and it is extremely difficult to finish the outer rendered shell when so close to the walls.

[George_M]

I will wait to dry and i will go for the second layer.
This layer is almost 1 1/2 inch.

[George_M]

[George_M]

[George_M]

[George_M]

Update!

[George_M]

Hi David,
I will start like your method but this method keeps the round shape of the dome or will make change in the final shape ?
Also,I will use only perlite-cement,this will stand easy or need a round base around it to keep it until dry ?

[david s]

Any ideas how to put perlcrete layer on my oven?
I will make 3inch width layer of perlcrete.

George,
Because a vermicrete mix has such a high proportion of water, it is important to make sure it is dry before rendering over it. I prefer to do it in layers of around an inch and a half with a week between layers to allow some drying, otherwise you end up trapping a lot of water that is hard to eliminate. I find the best way to apply it is with the hands, starting at the base of the dome and leaving a flat top onto which you can sit more mix once you've got all the way around. Use rubber gloves or the cement will damage your hands leaving you with raw fingertips. You can get a very good final surface by tapping the outside with the flat of your trowel.

[George_M]

Any ideas how to put perlcrete layer on my oven?
I will make 3inch width layer of perlcrete.

[George_M]

Ok david,i will buy clay to use..
Btw, Chimney ready!

[david s]

No, sand or chamotte will make the mix stronger, but will reduce the insulating capacity of the mix. Use powdered clay which will impart some stickiness which helps in the application. For every 10 litres of vermiculite add 1 litre cement and a handful of powdered clay. Mix well together dry then add 3 litres of water.

[George_M]

Can I use chamotte sand in the mix instead of fireclay ?
It is fine sand not grains ..
How much need to add in the perlcrete mix?
10-1-0.5 bucket is it good enough ?
Thanks David!