Insulation and heat break

[DBinnema]

I left a small gap between my dome and entry arch as a heat break.
Would filling this heat break gap with vermicrete make sense / be Ok in regards to thermal expansion? I'll just leave the heat break gap on the bottom to be filled with ash, but If I leave the gap around the sides / top open, then the insulating blanket I plan to cover the dome with would be exposed to the inside of the oven along the gap. This doesn't seem like a good idea.

I was also wondering if covering the entry arch in vermicrete, and keeping the insulating blanket I have for the dome, makes sense in terms of maximizing the insulating benefits of the blanket. I would cover the arch, and fill the heat break gap with vermicrete, then cover the dome in insulating blanket with vermicrete on top - and then stucco it all.

[NCMan]

Re: Insulation and heat break

I left a similar heat break on my oven. While building, I placed ceramic fiber tape in between each surface, to slow down heat loss. After all was built, I sealed around the gap, inside and outside w/high temp sealant. I have seen the outside insulated w/vermicrete before and I would imagine it works quite well. My 2?.

[david s]

Re: Insulation and heat break

I left a small gap between my dome and entry arch as a heat break.
Would filling this heat break gap with vermicrete make sense / be Ok in regards to thermal expansion? I'll just leave the heat break gap on the bottom to be filled with ash, but If I leave the gap around the sides / top open, then the insulating blanket I plan to cover the dome with would be exposed to the inside of the oven along the gap. This doesn't seem like a good idea.

I was also wondering if covering the entry arch in vermicrete, and keeping the insulating blanket I have for the dome, makes sense in terms of maximizing the insulating benefits of the blanket. I would cover the arch, and fill the heat break gap with vermicrete, then cover the dome in insulating blanket with vermicrete on top - and then stucco it all.

Yes, that's what I do although the heat break for my ovens is between the decorative arch and the entry. Vermicrete works pretty well to fill the gap. I jamb some alfoil or tissues in the bottom of the gap at the top to prevent the vermicrete falling through. Remove it when the vermicrete has set.

[DBinnema]

Re: Insulation and heat break

In looking around the forum I read someone else (david s) suggest filling the heat stop gap with vermicrete - but suggested substituting lime for cement. I suppose that makes sense...
Can it be just vemiculite 10:1 lime with no cement??

[david s]

Re: Insulation and heat break

I use 8:1 vermiculite and cement with a little clay added to make a more workable mix, but my thermal break/expansion joint is in a slightly cooler spot(between the decorative arch and the flue gallery) so normal cement stands up ok there. If it is between the flue gallery and the dome it will get much hotter and replacing it with lime might be a good idea.