12
Assembly Instructions - (cont.)
3. Earthcore mortar can be troweled over the face of a joint
where it has squeezed out while setting components. It is not
intended that the exposed faces of the Isokern components be
completely covered with the mortar.
Installation:
Step 1: Set the STANDARD base plate in a full bed of Earthcore
Mortar flat on a proper concrete support foundation. (Figure 11).
Do not set the STANDARD base plate so that it is in span. Level
the STANDARD 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. (Figure 9) 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 sup
-
port slab.
If the design preference is for a raised hearth (floor of
the fireplace elevated above the room’s floor), then the
STANDARD base plate can be set on a noncombustible
platform that is built up to the desired raised hearth height
on the concrete support slab. (Figure 10)
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 STANDARD base plate. Be sure to mortar the concrete
block platform 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. (Figure 11)
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 compo
-
nents connect.
FIGURE 9
FIGURE 11
FIGURE 10
