web analytics
hearth slab - Forno Bravo Forum: The Wood-Fired Oven Community

Announcement

Collapse

New Forno Bravo Forum Feature

Forno Bravo Forum Community,

You will notice a new forum at the top of the main page called, "Ask Me Anything". This forum will be used for live one hour "Ask Me Anything" (AMA) sessions hosted by people who are knowledgeable in different areas pertaining to wood fired ovens. How it works:
- Each AMA will have a "sticky" thread where the community can post questions they would like answered during the live session. This will allow everyone to participate even if you can't be online for the live session. These questions will not be answered by the host until the live AMA; if you need an answer quickly, you should post it in the appropriate Forum area for the community to respond.
- Another thread will be posted for the live AMA. Registered users who are logged in during the live session can interact with the host by asking questions and receiving responses.
- The live thread will remain in the AMA forum to view after the session.

To kick off our AMA feature, we have invited author, chef and master bread maker and host of Pizza Quest, Peter Reinhart, to be our first host! Peter will be in the Forum on Monday, February 15th, from 7:00 - 8:00 pm EST. If you are unable to be online during the live session, you can post your questions in the sticky post. Peter will answer those questions during the live session on February 15th. You can view Peter's answers to your questions as well as what happened during the live session in the session thread.

We hope you enjoy this new feature! Please let us know if there is a topic that you'd like to have as an AMA and we'll look for a host!

Forno Bravo
See more
See less

hearth slab

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • hearth slab

    Hopefully someone can answer this, I'm building a bread baking oven that will be in daily use(Sunday excepted), a cross-section of the hearth will be as follows: 4" firebrick.4" thermal concrete reinforced 8" vermiculite mortar. Is this enough insulation and secondly should the vermiculite mortar layer given its thickness also be reinforced with a rebar matrix.

    David

  • #2
    Re: hearth slab

    Hi David,

    I can answer this question! Yes I think it is enough insulation under the hearth.

    My build is a bit of a hybrid, but my hearth is similar:
    115 mm of firebrick (about 4 1/2")
    100mm (4") reinforced concrete (as a "floating" slab, so separated from the surrounding base structure)
    150mm (6") Vermicrete insulation underneath.

    A link to my build: http://www.fornobravo.com/forum/f21/...ula-20323.html

    Admittedly I have only cooked in my oven twice, but on both occasions I had the internal temp up around 500C at the dome and under the Vermicrete it was mildly warm at best (OK to leave my hand there as long as I liked). My dome has no extra thermal mass but is well insulated, and the next day after firing the internal temp is still around 250C.

    I didn't put any reinforcing through the Vermicrete layer, and it didn't need it. I put a few large screws between the vermicrete and concrete layers, and I also put a few short pieces of rebar (3-4") from the sides of the Vermicrete into the blocks of the stand before I core filled them. I was a bit worried about the weight of the Vermicrete layer being held by those crews only. I'm still not sure if this was overkill but it didn't hurt. I think to put rebar all the way through the Vermicrete might detract from its insulating properties?

    Having said all that, I think there are probably better ways to insulate under the hearth slab. On my next build () I think I will investigate polystyrene blocks (eg Foamex) for under the concrete hearth slab. Surely these would be easier to fit and better insulators?

    Hope that helps.

    Andrew

    Comment

    Working...
    X