HEI150 Wood Insert Fireplace Installation and Operation Manual
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If the extension of the masonry hearth is raised at least 8" (F) from the floor protection, a
non-combustible material without an R factor extending 16" (406 mm) (USA)/18’’ (457 mm)
(CAN) from the front of the insert is required.
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 is required.
The use of an R value is convenient when more than one material is going to be used in the
hearth extension to cover the combustible surface. This is because R values are additive,
whereas K values are not.
There are two ways to calculate the R factor of the floor protection. First, by adding the R-
values of materials used, or by the conversion if the K factor and thickness of the floor
protection are given.
To calculate the total R factor from R factors of the materials used, simply add the R-values
of materials. If the result is equal to or greater than the R-value requirements, the