16
Fireplace Finishes & Combustible Trim
Clearances
Hearth Material & Dimensions – Codes are strict regarding the
use of proper materials for hearth extensions and the proper
dimensional characteristics.
All hearth extensions must be made of code-rated,
noncombustible materials such as tile, brick, concrete or
stone. MASON-LITE Fireplaces usually have an opening of
approximately 8 sq. ft. (eight square feet) that translates to a
hearth extension of about 20” (twenty inches) at the fireplace’s
opening and about 12” (twelve inches) extension at each side.
These relative dimensions are also covered by code.
Figure 35
43"
NON-COMBUSTIBLE
HEARTH EXTENSION
BOTH SIDES
1
1
2
"
24" min
12
20
30"
20"
GRATE SIZED
50% OF HEARTH
AREA MAX.
Note that it is required that metal safety strips must be laid on
the floor of the non-combustible raised platform. These should
be 26 gauge and measure 4” (four inches) wide. They need
to extend half way under the platform and half way under the
hearth extension material (see Figure 19).
Attention:
You will note that there will be a gap between the
fireplace front and the extension of the non-combustible hearth
material. Be certain that you seal this with non-combustible
material.
1/2" THICK
CONCRETE
BOARD
CLASS "A"
CHIMNEY
SEE FIG.
29 AND 30
SEE FIG. 27
2" AIRSPACE
CLEARANCE TO
COMBUSTIBLES
ON REAR AND
SIDES OF UNIT.
ONLY NON-COMBUSTIBLE
MATERIAL WITHIN 18” OF
TOP OF OPENING.
28”
8” METAL
PLATFORM
1/2”
2”
seal gap with
non-combustible
material
Figure 36
Mantle and Mantle Shelf Clearances
As with any radiant heat fireplace, all MASON-LITE Fireplaces
must comply with building code safety clearances, for units
that have openings of 6 sq. ft. (six square feet) or greater.
For Mantel clearances see Figure 9.
Walls that Adjoin – your fireplace cannot be installed closer
than 2 ft. (two feet) to any adjoining walls in the room where
the fireplace is.
Caution in Regards to Combustibles – If any part of the
fireplace or objects in the room (curtains, rugs, paint, cushions,
etc.) start to show warping or discoloration due to heat from
the fireplace, it is time to take immediate action. Do not use
the fireplace until you have figured out how to address the
problem. You are facing a potential fire hazard. MFI cannot be
responsible for the make-up of material on the exterior of the
fireplace you have chosen, nor can MFI be held responsible
for the materials in a room that may be responding negatively
to heat. However, in almost all cases, there is a solution to
the problem, either by making adjustments to airflow or the
modifications to the room itself.
Installing Outside Combustion (make-up) Air
1) The Mason-Lite Fireplace needs enough make-up air to
function properly and some local building codes may require
outside combustion air to be provided. If no make-up air is
provided, improper flue drafting may occur, creating negative
pressure whereby smoke may enter the home, especially in
homes that are very well insulated and tightly sealed. Check
local building codes for specific requirements.
2) Install Combustion Air Kit MFP4-AK into the MASON-LITE
Firebox through the side wall opening provided. The tubing
that goes out of the firebox wall must feed into a flexible metal
conduit as the source for outside combustible air. It can go
straight out through an outside wall or into a ventilated crawl
space. If crawl space is used, check codes for proper
termination.
Figure 37
Internal
Wall
Installation
Island
Installation
Outside Air supply
from side wall or
ventilated crawlspace
Outside Air supply
from crawlspace
