Osburn OB02401 - Manual (Page 8)

8
2.2 Installation instructions
Inspect the masonry fireplace according to the safety information and fireplace requirements and
have it cleaned and/or upgraded as necessary.
2.3 Compliance of the masonry fireplace
Where the masonry fireplace opening is 6 ft
2
(0.56 m
2
) or larger, the hearth extension shall extend
at least 20'' (508 mm) in front of the facing material and at least 12'' (305 mm) beyond each side of
the fireplace opening. Where the masonry fireplace opening is less than 6 ft
2
(0.56 m
2
), the hearth
extension shall extend at least 16'' (406 mm) in front of the facing material and at least 8'' (203
mm) beyond each side of the fireplace opening.
Note that if you must modify the hearth extension to comply with these measures, depending on
the size of the masonry fireplace opening, the hearth extension must have a minimum of
4'' (102 mm ) thick (see Figure 2.6a and 2.6b.)