3. The Insulating Hearth
Overview
Your oven sits on a two-piece hearth, comprised of an
insulating layer that rests on top of a structural layer. We
recommend using FB Board for under oven insulation, as
it is easy to install and very efficient at holding heat inside
your Casa oven. If you are using FB Board, pour a rebar
reinforced 3
½
” pad using a 2”x4” form, and place the FB
Board on top of the pad.
If you are using vermiculite concrete for insulation, you
pour the hearth in two parts: a 3 1/2" layer of structural,
rebar reinforced standard concrete, followed by a 4" layer
of insulating concrete, using a 2”x8” form.
Instructions
The hearth form is built in two parts: a bottom tray and the
frame sides, which will hold the hearth as it is poured.
After the hearth has cured, the form is removed (and
usually becomes part of the first fires that will cure your
oven).
Bottom Form Support
First, using 2"x4" lumber build the frame for the bottom of
the form. The frame should be roughly 3/8" smaller than
the opening of your block stand, so that it can be easily
removed after the hearth has cured.
Next, cut (12) lengths of 2"x4" that will serve as the legs
that hold the bottom frame in place inside the stand
opening. You will use 1/4" shims to accurately set the top
of the frame. The top of the 2”x4” frame should be about
1" below the top of the stand (to allow for the 3/4" plywood
and shims). Measure and cut your 2”x4” legs accordingly
-- stand height, minus 2 1/2" (1 1/2" for the 2”x4” and 1" for
the plywood and shim).
3.1. The form ready for the tray.
Set two 2”x4" legs at each corner and one in the middle of
the span, then lay the frame on top. Place shims between
the legs and frame, and then tap the shims to raise the
frame up until its top is 11/16" (the true thickness of 3/4"
plywood) from the top of the stand. After the bottom tray is
built, you will add more 2“x4” legs to support the center of
the tray.
Artigiano Installation and Operating Manual
© Forno Bravo, LLC 2008/9. All Rights Served.
Ver. 2.2
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