(See Appendix K of 780 CMR and the Manufacturer's requirements)
Solid fuel-burning appliances can radiate significant amounts of heat energy from the underside of the appliance or through glass fireplace doors. Therefore, it is necessary to know what floor protection is required when such appliances are being installed on combustible floors.
The appliances must have floor protection clearances and other requirements listed on the label or otherwise in the Installation Manual.
On matters of floor protection, appliance Installation Manuals will typically use terminology addressing thermal conductivity ("k") and/or thermal resistance ("R") and for guidance on such requirements seek expert assistance and Building Official inspection/approval of floor protection.
Typically a decorative tile-covered or brick-faced insulation board hearth extension cannot be used because it will have much too high of a "k" value (too low an "R" value). You should consult the Manufacturer's requirements and Appendix K of 780 CMR. Additional technical guidance on how to calculate "k" and "R", is found by link at the back of this Detailed FACT SHEET.
Please be aware that while rug-like hearth mats may be non combustible, they may not be safe to use. They often allow too high a "k" value (too low an "R" value) for a combustible floor finish or substructure.
If you have any questions on this issue, you should contact your local building official.
VI. Prior to use, the Solid Fuel-burning Appliance Installation Must be Inspected by the Building Official to Ensure Compliance to the Building Code
(See 780 CMR, Sections 108.3.5, 110, 111, 6007 - 6008 and Regulations R5 and R6 and the Appliance Manufacturer's Installation Manual)
VII. Maintained in Accordance with the Appliance Manufacturer's Requirements
(See the Appliance Manufacturer's operations and maintenance requirements)
Solid fuel-burning appliances must be properly maintained in order to perform efficiently. Failure to maintain vent terminations and chimney openings can result in serious injury and death due to potential build up of carbon monoxide gas in the building.
You should only use appropriate fuels such as seasoned wood and proper type of coal or pellets. Never use liquid or gaseous fuels in a solid fuel-burning appliance or otherwise substitute a fuel type.
You must regularly clean vents and chimneys to avoid creosote build up which may cause chimney and vent fires.
MASONRY FIREPLACES, FACTORY-BUILT FIREPLACES AND MASONRY AND FACTORY-BUILT CHIMNEYS
For 1 & 2 Family "stand-alone" dwellings, fireplaces and chimney systems are addressed in 780 CMR 6007 - 6008.
Any fireplace or chimney installation, construction or reconstruction requires a building permit before any such work may begin.
Additionally construction inspections by the building official are required.
FREQUENTLY ASKED QUESTIONS AND SAMPLE CALCULATIONS