Osburn OB02401 - Manual (Page 11)

11
If a non-combustible material floor protection needs to be added in front and level with the hearth
extension masonry fireplace (see Figure 2.6a), an R factor equal to or greater than 1.00 is
required. If the extension of the masonry hearth is raised at least 4" from the floor protection
(see Figure 2.6b), a non-combustible material without an R factor is sufficient.
Figure 2.6a
Figure 2.6b