web analytics
Concrete hearth--Vermiculite on top or bottom?? - Forno Bravo Forum: The Wood-Fired Oven Community

Announcement

Collapse

I'm Peter Reinhart! Ask Me Anything! Monday, February 15, 2016 7:00-8:00 pm EST

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.

Ask Me Anything New Forum Feature

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.

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

Concrete hearth--Vermiculite on top or bottom??

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

  • Concrete hearth--Vermiculite on top or bottom??

    I am in the process of building my WFO and have found this fourm the other day and saw on here that some put the Vermiculite base on top of the hearth. I was planning on putting mine at the bottom in a Vermiculite / Portland Cement mix of 2" them pour the other 4 1/2 part of the slab in conrete and then putting my firebrick on the side for the bottom of the oven. Not sure the differnece? Wondering if anyone had any advice on this
    Toby

    Columbus, NE

  • #2
    Re: Concrete hearth--Vermiculite on top or bottom??

    If you do it like you plan, you will be using the slab as a heat sink. You will have to get that mass to temperature and that could take a long time. Done as shown on the FB plans, the floor mass is just the firebrick, and that alone is hard to get hot enough.

    Comment


    • #3
      Re: Concrete hearth--Vermiculite on top or bottom??

      Was just wondering the difference. Would that be better if I am also planning on baking bread in the oven. My guess is more mass, less cool down time?
      Toby

      Columbus, NE

      Comment


      • #4
        Re: Concrete hearth--Vermiculite on top or bottom??

        Toby,
        My oven is constructed using the FB plans. My oven is 550 degrees the next morning after cooking pizza ( that is without a proper insulated door, just covering the opening with fire bricks cut to size). If you are planning on baking large quantities of bread, ie multiple oven loads then the 4" concrete slab will hold heat longer, but it will also take a long time ( and a lot of wood) to get up to temp. Most people on this site use the perlite/portland insulating layer with the firebrick set on top of that so the cooking floor is 2.5" thick. If you want more thermal mass you could set your floor with the bricks 4.5" thick.
        Eric

        Comment


        • #5
          Re: Concrete hearth--Vermiculite on top or bottom??

          Yes, the support slab is a HUGE heat sink if you don't insulate between the slab and the floor. The only reason to build an oven with massive extra thermal mass is if you are planning to bake commercial quantities of bread. For home use, there is no reason to make the oven any thicker than the thickness of a firebrick on the floor, or the width of one on top.

          Many who have built the oven according to plan note that it takes far too long to cool the oven off from pizza temperatures to bread baking temperatures to do both in the same evening. Insulation is the key.

          On that topic, two inches of vermiculite concrete isn't nearly enough. We recommend four. If your design limits you to two inches for insulation, use a refractory insulation board.

          Good luck with your project.
          My geodesic oven project: part 1, part 2

          Comment

          Working...
          X