The Ontario Building Code | Underground Walkways
3.1.13.9. Underground Walkways
(1) Except for paint, the interior wall and ceiling finishes of an underground walkway shall be of noncombustible materials.
In Plain Language
Except for paint, every interior wall and ceiling finish in an underground walkway must be noncombustible.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.