Bricks-ceramic blanket-vermicrete-ceramic blanket-stucco?

[Puy de Dome]

I'm not very happy about the insulation on my oven. I have the following:

Fire bricks in the dome, followed by a one inch ceramic blanket and then varying degrees of vermicrete.

It varies from the sides to the top because I found it quite hard to get the stuff to stick on the sides.

Now, I could just apply another layer of vermicrete - again thickening the top third and only just bringing the sides up to the proper spec, and then stucco (render in the UK).

Or...

Apply one more one inch blanket over the bottom two thirds of the oven with chicken wire and then stucco this and the rest of the oven. The idea being that the blanket is easier to put in place than vermicrete.

Am I mad or suggesting the best I can do?

PdD

[nissanneill]

Yes, getting your vermiculite cement insulation to stick is pretty tricky, especially down the vertical sides.
I ended up putting a small percentage of fireclay in the mix which made it much stickier and used a brickies trowel to hold the mix and a steel cement trowel to push the mix onto and ALWAYS UP THE DOME to get it to stick. I eventually started at the top and worked my way down and around the dome.
I have a full explanation with picks and tips in my 40" Pompeii build at:

http://www.fornobravo.com/forum/f8/n...-1-a-2005.html

just follow the threads. You will find it and get it solved without frustration as I have done that for you.

Neill

[Puy de Dome]

Thanks Neil

IS there any mileage in applying a one inch layer of blanket around the bottom two thirds of the oven?

[Ken524]

Throwing more blankets on will certainly improve insulation (and is a LOT easier to apply than vermiculite).

[nissanneill]

I personally would not put an extra layer of blanket around the bottom purely for the reason that you will then have to layer chicken wire and then the problem of vermiculite over that. If you already have a layer of vermiculite cement over your bottom courses, mix a batch (with a small percentage say .5 of one part fireclay) and apply it at around 1" thickness. A couple of hours later, repeat that and come further up the dome. It will stick well and much easier than putting it onto the blanket.

To finish your waterproofing coat, mix a stucco or 'plaster layer' that is 3 parts plaster sand to 1 part portland cement. This is the easiest to apply around 1/2" thick which will then provide the waterproofing layer. You can then tile over this, paint it or even put another textures layer on top but it will not increase you insulative capability of your dome.

Good luck.

Neill