Installation:
Step 1: Set the Standard EPA qualified fireplace base plate in a
full bed of Earthcore Mortar flat on a proper concrete support
foundation. Do not set the base plate so that it is in span. Level
the base plate by floating it in a bed of Earthcore Mortar to full
bearing against the underlying noncombustible support surface.
Notes:
If the design preference is for a “flush hearth” (fireplace
floor flush with the room’s floor), the base plate can be omitted
from the assembly and the firebox walls built directly on the
concrete support slab. The fire brick floor of the firebox is then
set directly to the concrete support slab. This makes the fireplace
finished fire brick floor approximately one and one-half inches
(1-1/2”) above the top of the concrete support slab.
If the design preference is for a raised hearth (floor of
the fireplace elevated above the room’s floor), then the base plate
can be set on a noncombustible platform that is built up to the
desired raised hearth height on the concrete support slab.
When calculating raised hearth height be sure to allow
for the three inch (3”) thick base plate plus the one and one half
inch (1-1/2”) thick fire brick floor in addition to the height of the
platform. Whether a flush hearth is preferred or a raised hearth,
the combustible floor on front of the fireplace must be covered
with a noncombustible hearth extension set tight against the fire
-
place front and extending at least 20 inches out from the finished
fireplace and at least 12 inches beyond the finished sides of the
fireplace opening.
For all “raised hearth” construction where concrete
blocks are used to create the raised platform, it is necessary to
use the base plate. Be sure to mortar the concrete block plat-
form together. CMU used for base plate support should be rated
ASTM 90.
Step 2: Set the first course of the firebox back wall and side
walls into place.
It may be convenient to dry set the first course of side
wall and back wall into place on the Isokern base plate and then
to trace their position on the base plate with a pencil.
After outlining the dry set pieces, remove them and
apply Earthcore Mortar to the areas traced on the base plate
where the side walls and back wall are to sit. By doing this, the
first layer of wall components can be set directly into mortar
already applied to the proper areas on the base plate.
Be sure to put Earthcore Mortar on the contact surfaces
of the vertical joints where the side wall and back wall
components connect.
Assembly Instructions - 36 C
11
Raised hearth
for wood or
concrete installs
Flush Hearth
on Concrete
Foundations Only
Earthcore
Mortar
