The Ontario Building Code | Hydrostatic Pressure
9.16.3.2. Hydrostatic Pressure
(1) Wheregroundwater levels may cause hydrostatic pressure beneath a floor-on-ground, the floor-on-ground shall be,
(a) a cast-in-place concrete slab, and
(b) designed to resist such pressures.
In Plain Language
Where hydrostatic pressure (groundwater pushing against the slab) is a concern, this article sets out the additional measures required to resist that pressure.
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.