R1001.9.2

Section R1001.9.2 is titled 'Hearth extension thickness' and covers requirements for masonry fireplaces. The minimum thickness of a hearth extension is established. The purpose of this section is to prevent the building from catching fire. This section has an exception which allows for a thinner hearth extension where the hearth is located higher above the hearth extension. The purpose of the exception is to allow for an alternative arrangement where the risk of the building catching fire is reduced.

The model shows 2 partial sections of a fireplace and chimney assembly with the hearth and hearth extensions highlighted. The 1st assembly demonstrates the standard code language, and the 2nd demonstrates the exception.