Osburn OB01801 User Manual
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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
