5.3.6 Hearth and Hearth Extensions
5.3.6.1 Hearth Extension and Fire Chamber Depth
The distance from the back wall of the fire chamber to the front
edge of the hearth extension shall be not less than 28 in. (700 mm),
and the hearth extension shall extend not less than 16 in. (400 mm)
in front of the fireplace opening
.
.
5.3.6.2
Where the hearth floor is elevated at least 6 in. (150 mm) above the hearth
extension, the width of the hearth extension shall be increased by:
(A) 2 in. (50 mm) for an elevation of between 6 in. (150 mm) and
12 in. (300 mm); and
(B) an additional 1 in. ( 25 mm) for every 2 in. (50 mm) in elevation
above 12 in. (300 mm)
5.3.6.3
All hearth extensions shall extend not less than 8 in. (200 mm) beyond
each side of the fire chamber.
5.3.6.4
The hearth and hearth extension shall be supported on not less than a 4 in.
(100 mm) thick reinforced concrete slab. For cantilevered, raised hearth
extensions, this slab may taper to not less than 2 in. (50 mm) at the front
edge and ends except as provided in Clause 5.3.6.5.
5.3.6.5
(A) When a fireplace opening is raised 8 in. (200 mm) or more from a
combustible floor, the hearth extension or pad may be placed on the
combustible floor and shall be not less than 2 in. (50 mm) thick when made
of a single unjointed unit of artificial or natural stone, or of reinforced
concrete.
(B) When thin material less than 1 in. (25 mm) thick (ie, tile or slate) is
used a bedding of steel mesh reinforced grout or concrete shall be
provided. The composite thickness shall be not less than 2 in. (50 mm)
(C) Jointed units of tile, slate or other noncombustible material more than
1 in. (25 mm) thick may be installed in conformance with Item (B) or shall
be placed over a continuous layer of sheet metal with a thickness of not
less than 0.5 mm.
(D) Mastic or grout used to place tile, slate or other thin masonry units
shall be noncombustible.
,
,
.
If the hearth
is elevated
between 6”
and 12” *
* If the hearth is elevated more than
12” see Article 5.3.6.2. B)
8”
16”
18”
8”
Before installing a Don-Bar insert the owner must ensure that its existing
masonry fireplace meets the requirements of CSA A405 (excerpts below). Failing this, the
required modifications must be executed by a licensed contractor.
MINIMUM DIMENSIONS FOR THE
HEARTH EXTENSION
If the hearth
is elevated
protect the
vertical surface
under the hearth
as specified
in theArticle
5.3.6.7
PROTECTION OF THE VERTICAL
SURFACE UNDER THE HEARTH
Note: The CSA A405 Standard governs the
construction of masonry fireplaces and
contains several other articles.
APPENDIX 1 - REQUIREMENTS
FOR EXISTING FIREPLACES
Page 25
REV. 2014-11
