Astria.us.com
126647-01_E
6
Example 1:
The face of a mantel, bookshelf, etc. is made of combus-
tible material and protrudes 2
3
/
4
" from the wall on which the fireplace
is installed. The combustible material must be a minimum of 4" from
side of fireplace opening.
Example 2:
The face of a mantel, bookshelf, etc. is made of com-
bustible material and protrudes 11/16" from the wall on which the
fireplace is installed. The combustible material can butt up against
side of fireplace (i.e. 1" from fireplace opening).
FIREPLACE INSTALLATION
Continued
HEARTH EXTENSION
A hearth extension projecting a minimum of 20" in front of and a
minimum of 12" beyond each side of fireplace opening is required
to protect combustible floor construction in front of fireplace. Fab-
ricate a hearth extension using a material which meets the following
specifications: a layer of noncombustible, inorganic material having
a thermal conductivity of k = .84 BTU IN/FT
2
HR °F (or less) at 1"
thick. For example, if material selected has a k factor of 0.25, such
as glass fiber, the following formula would apply:
0.25 x 1.0" = 0.30" thickness required
0.84
Thermal conductivity "k" of materials can be obtained from manu-
facturer or supplier of noncombustible material. If hearth extension
is to be covered, use noncombustible material such as tile, slate,
brick, concrete, metal, glass, marble, stone, etc. Provide a means to
prevent hearth extension from shifting and seal gap between fireplace
frame and hearth extension with a non-combustible material such
as sand-cement grout (see Figure 3, page 5).
WARNING: Hearth extension is to be installed
only as shown in Figure 5.
MANTEL CLEARANCES
Woodwork such as wood trims, mantels or any other combustible
material must not be placed at least 9" above opening of fireplace
(see Figure 6, page 6). Combustible materials above 9" and projecting
more than 1 1/2" from the fireplace front face must not be at least
12" above fireplace opening (NFPA 211, Section - Clearance from
Combustible Material).
Mantels or any other combustible material may also come up to the
side edge of the black metal face of the fireplace. Clearances from
side of fireplace to any combustible material and wall should fall
within the limits show in Figure 7.
Figure 5- Hearth Extensions
Figure 6 - Mantel Clearances
Figure 7 - Minimum side clearances
Seal Cap
Do Not Block Louver
Seal Cap
Ember
Protector
Ember Protector
Hearth
Extension
Hearth
Extension
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
11/16
1
3
/
8
2
1
/
16
2
3
/
4
3
7
/
16
4
1
/
8
4
13
/
16
5
1
/
2
6
3
/
16
6
7
/
8
7
9
/
16
8
1
/
4
8
15
/
16
9
5
/
8
No Combustible
Material on Face
of Firebox
Fireplace
Opening
Example 1
Example 2
1" Both
Sides
Minimum 24" from Perpendicular Side Wall
12
1
/
4
"
(312 mm) Ref.
6"
(153 mm) Ref.
12"
(3045 mm)
Min.
9" (229 mm) Min.
1
1
/
2
"
(39 mm)
Max.
3" (77 mm)
Nom.
33°
Combustible
Material
Safe Zone for
Projection of
Combustible
Materials
Fireplace Opening
Upper
Section of
Fireplace