3.1. The form support 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 (Photo 3.2).
3.2. Form supports.
The Bottom Tray
The bottom of the hearth form can be build using either
plywood, which must be removed, or with Hardibacker,
which can be left in place.
To form the tray bottom using Hardibacker, cut the backer
board to rest on top of the concrete block stand, supported
by the form supports. Leave a few inches of space between
the backer board and the outside edge of the stand to allow
concrete to fill into the cores of the stand blocks.The
concrete hearth will be poured on top of the backer board,
and the backer board will stay in place, becoming the roof
of the oven wood storage area.
3.3. Hardibacker inside the side forms.
To form the tray with plywood, cut two sheets of plywood
lengthwise to fit into the opening (3/8" shorter so that it will
easily come out later), and lay it on the frame. Tape the joint
with masking tape. Set your last two 2"x4"legs supporting a
2"x4" on its side directly under the joint, which will support
the weight of the wet hearth while it is curing. Shim to level.
To prevent the concrete from bonding to your forms you can
either get a commercially available release agent (usually a
spray) or use a homegrown method of vegetable oil, which
may render the plywood useless for other projects.
Pompeii Oven Instructions
© Forno Bravo, LLC 2007-2009. All Rights Served.
Ver. 2.0
27
