Century CW2900 Insert Installation And Operation Manual page 36

CW2900 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 2.00 is
required.
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