Osburn 2200 OB02201 Installation And Operation Manual page 33

2200 Insert Installation and Operation Manual
If the extension of the masonry hearth is raised at least 4" from the floor protection, a non-
combustible material without an R factor is sufficient.
If non-combustible material floor protection needs to be added in front of and level with the
hearth extension of the masonry fireplace, an R factor equal to or greater than 1.00 is required.
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