Oven floor insulation

[LGM]

Shout out to everyone on the forum! Much praise to all of you builder ?veterans? willing to take the time to share your experience/expertise. It is appreciated by us ?new guys.?

So, I?ve built my foundation and base, now I?m ready to move forward with building the dome. Having some difficulty deciding on the dome floor insulation. Looking for some opinions!
Originally, I was going to build a 40? oven. However, after some calculation, I realize that the oven would be 49? wide (outside diameter). Since the ceramic board comes in 24?x48? sizes, I have decided to pare down to 39?, making the outside dimension 48?. According to my calculations, this would mean I need approximately 3 pieces of 2? thick, 24? x 48? Ceramic board (FB).
However, this stuff is pretty expensive!
I have read some threads and noticed that some wished they had more insulation under the floor.
Thinking about putting a layer of vermiculite mix under 2? of ceramic board.
This is the part where I would appreciate your opinions.
Is ceramic the best to use?
How do the mineral boards, such as Insblock 19 perform? (seems to be much less expensive!)
Or other alternatives like calcium silicate boards, such as Superisol board?
Would 3.5 ? of vermiculite mix and the 2? of ceramic be a recommended approach or swap the ceramic for 3? or 4? of Insblock 19?
Thanks,
Larry
Gratzi mili tuti

[Gulf]

Re: Oven floor insulation

If you are leaning toward pairing insulations, you might want to think about Calcium Silicate (CalSil) and vermicrete. Heck, if you did some searches locally for CalSil, you might find that it is cheaper to go that route. Search locally for industrial or commercial insulation suppliers in your local area.
EDIT: I should have read thru your post again. I see that calcium silicate was one of your options. Based on my research, recomendations from this site, and my local pricing: 2" Calcil and 4" of 5-to-1 vermicrete gets my vote.
I think that your 3 and 1/2" vermicrete would be sufficient.

[Aegis]

Re: Oven floor insulation

I used 4" of foamglas and it has performed great! I was tempted to use another 2" piece but was stopped by the additional height it would have added. Would have made the hearth height a bit too high for our use. Keep the hearth height in mind when you add insulation.
Good Luck
John

[GianniFocaccia]

Re: Oven floor insulation

I went with 3 1/2" of Vermicrete and 2" of Insblock 19 on my 39" Pompeii. I don't think you can go wrong with this config.

[PizzaIdiot]

Re: Oven floor insulation

When I was planning my oven I decided to go with 5" of perlcrete (perlite + portland cement) for my 42". It's a lot cheaper than the Insblock.
I can't say how well it's worked because the domes not done yet, but the feedback here said to use at least 4".
My advice is to go with 5" and skip the CalSil.
Jeff

[LGM]

Re: Oven floor insulation

Not only am I a new guy to oven building, I am a new guy to "Forums" as well. Not sure if I am responding in the correct place, hope so!!
Thanks for the quick response, and recommendations. Gulf, I did some research and found a very good price (I think!) on some CALSIL TR-20. Whatever that is! Anybody ever used it? Heck, anybody ever heard of it? I tried to do a ?Google? search, but did not find much. There is a CALSIL-TR20 Block, but not the 24? x 2.5? x 36? board, that I can get my hands on.
If this stuff is good to use, I may forgo the vermiculite layer, and do two layers of the 2.5? thick CALSIL. The additional cost for the second layer would only be slightly greater than the cost of the vermiculite layer. Plus, no labor involved! (No issues on the height, as I wanted to get the oven up a few extra inches anyway!)
I have another question, Is there a big difference in the medium duty to the low duty firebricks?
Also, I forgot to give some details on the oven that I am building, (if anyone cares!)
I am doing a 39? highbred, Pompeii/Tuscan. Not sure yet if it will be an ?igloo? or enclosed. The aesthetic engineer (aka? the wife) has not told me yet. (I?m just the cheap labor!)
I live in the southern part of Atlanta, where I should be able to use the oven, a good 10 months a year. I built the pool last year, the oven is this year, and the outdoor kitchen is next year (if everything goes as planned!)

Larry

[azatty]

Re: Oven floor insulation

I have Insblok 19 and 4 inches of 5:1 vermicrete under my hearth. You can source the Insblok locally through a ceramic supply company. Two inch Insblok 19 comes in 1 x 3 foot sheets, so you can lay whole sheets without cutting as much.

[Gulf]

Re: Oven floor insulation

Not only am I a new guy to oven building, I am a new guy to "Forums" as well. Not sure if I am responding in the correct place, hope so!!
Thanks for the quick response, and recommendations. Gulf, I did some research and found a very good price (I think!) on some CALSIL TR-20. Whatever that is! Anybody ever used it? Heck, anybody ever heard of it? I tried to do a “Google” search, but did not find much. There is a CALSIL-TR20 Block, but not the 24” x 2.5” x 36” board, that I can get my hands on.
If this stuff is good to use, I may forgo the vermiculite layer, and do two layers of the 2.5” thick CALSIL.

Larry

Larry,
I did a quick search and was not able to come up with exactly what you described. Is the "block" possibly an insulated firebrick size? Most commercial and industrial applications use (as azatty described: 2 inch X 1 foot X 3 foot) size. Mine happened to be made by Johns Mansville Corp. (Themo-12 Gold)
You might want to refine your search a little and just look for commercial and industrial insulation suppliers in your area and phone the businessesfor a description and price. Like azatty was saying, the less cuts the better

[Gulf]

Re: Oven floor insulation

I'm not sure how far the South Carolina locations are from you but Distribution International has some decent prices in my area. If they are not close enough for you to drive and pick up, maybe they can refer you to a local distributor.
Hope this helps.

[LGM]

Re: Oven floor insulation

I decided to go with the 2.5? thick CalSil insulation blocks. Went to Larkin Refractory Solutions in the greater Atlanta area, an amazing supply of refractory products. I had no idea that fire bricks where produced in so many different sizes and shapes. Jim, the owner, was extremely friendly and helpful. A great source for anyone building an oven in the Atlanta area.
So, I am one step closer to getting this thing going. Now all I have to do is start cutting all the bricks.
Thanks again for response and input.
Larry

[slschoming]

Gulf You used Termo-12 Gold as your floor insulation? I downloaded a spec sheet and see that it has little grooves cut in the flat blocks, does that sound right?

I am currently looking for a floor insulation in my area and shipping is pretty expensive. However, we have a Johns Manville plant in my hometown where they manufacture different types of insulation. I might have to try to contact them and see if they produce the Thermo-12 Gold there and, if so, see if I can get some before it ships out of town.

[Gulf]

The scored insulation is for wrapping large diameter pipe. You should be able to get it without the notching.

[UtahBeehiver]

Gulf is right on the slotted Thermo Gold 12. Any CaSi or AiSi board with similar specs to Thermo Gold 12 will work. Check refractory supply houses.

[slschoming]

Thanks guys, I checked with a friend who works out there and was informed they don't manufacture the Thermo-12 Gold here so I am still looking. I have found a boiler supply company 60 miles away that I am in communication with but just waiting on some specs for the board that they have in stock.

[CoastalPizza]

Check with Specialty Products & Insulation in El Dorado, KS - it looks like they have everything you need; they list calcium silicate, cellular glass, and ceramic fiber.