Hearth construction question

[davidwilcox123]

Building a 38" pompeii. Base is built. Using one layer of high-duty bricks for insulation layer. It was suggested to me to put a piece of hardibacker down on top of the insulation bricks and then build the oven on top of the hardibacker. Please let me know your thoughts. Thanks in advance!

[Mike D]

Re: Hearth construction question

You might want to read up a little bit more before you start your build. Any type of bricks are not used for insulation (they create more thermal mass). If you don't use an insulation layer under your oven it will take forever to heat up and keep hot. Use the insulating board or make a layer with vermiculite/pearlite.
-I don't think hardibacker board is rated to get that hot (it might fall apart).

Good luck
Mike

[Les]

Re: Hearth construction question

It was suggested to me to put a piece of hardibacker down on top of the insulation bricks and then build the oven on top of the hardibacker.

I'm curious, who is this person? It defies everything we have learned, and built upon, from this site. You can download the plans from the FB store (free). And as Mike has suggested, read up a little more.

[GianniFocaccia]

Re: Hearth construction question

You may be confusing High-Duty Bricks for insulating firebricks. Just know that insulating firebricks (IFB) have the same r-value as vermicrete and while wonderfully uniform in construction and able to withstand compression, need to be at least 4" thick under an oven floor to be effective. IFB works ideally coupled with a layer of ceramic board.

[davidwilcox123]

Re: Hearth construction question

Les: loved your answer. Thanks.....

You're right. Needed some more information and an explanation. Thanks for the input. Simple step, now understood.

Less thermal mass!