As a home inspector, the important thing to know is most typical wall and ceiling assemblies (including tile and stone finishes set on conventional wood-framed walls) are considered combustible. Drywall is also considered a combustible material because of the paper facing.
In this regard, is cement board considered non combustible?
Yes, HardieBacker® 1/4" Cement Board is deemed noncombustible when tested to ASTM E 136 and can be used in conjunction with other noncombustible materials around a fireplace. This does not mean that clearances to combustible building materials can be reduced by using HardieBacker 1/4".
Is plasterboard fire resistant?
Since it is not possible to build a plasterboard partition without a supporting framework all of these components are vital to the overall fire resistance performance of the partition, therefore the plasterboard cannot be considered on its own in terms of fire resistance.
Is Stone non combustible?
While wall 'coverings' are frequently non-combustible — like tile, brick, stone, metal — the underlying structure often contains wood, paper faced drywall or insulation, and other materials that could catch fire if enough heat were to be transmitted through the 'non-combustible' wall covering.