Specifications
Solution 2.5-ZC Fireplace Installation and Operation Manual  43 
Thermal Characteristics of Common Floor Protection Materials* 
MATERIAL CONDUCTIVITY (k) 
PER INCH 
RESISTANCE (R) PER INCH 
THICKNESS 
Micore
®
 160  0.39  2.54 
Micore
®
 300  0.49  2.06 
Durock
®
 1.92 0.52 
Hardibacker
®
 1.95 0.51 
Hardibacker
®
 500  2.3  0.44 
Wonderboard
®
 3.23 0.31 
Cement mortar  5.00  0.2 
Common brick  5.00  0.2 
Face brick  9.00  0.11 
Marble  14.3 – 20.00  0.07 – 0.05 
Ceramic tile  12.5  0.008 
Concrete 1.050 0.950 
Mineral wool insulation  0.320  3.120 
Limestone 6.5 0.153 
Ceramic board (Fibremax)  0.450  2.2 
Horizontal still air** (1/8")  0.135  0,920** 
* Information as reported by manufacturers and other resources 
** For a 1/8" thickness. You cannot «stack» horizontal still air to accumulate R-values; you 
must separate each layer of horizontal still air with another non-combustible material. 
6.3.2  Minimum Heart Extension Requirements 
The hearth extension floor area must extend at least 16" (41 cm) in front of the hearth (A) 
and at least 8" (20 cm) on each side of the door opening (D). The joint between the hearth 
extension and the fireplace hearth needs to be made of non-combustible material such as 
sheet metal (not included). 










