The Ontario Building Code | Support of Floors
(1) Material that is susceptible to changes in volume due to variations in moisture content or chemical-microbiological oxidation shall not be used as fill beneath floors-on-ground in a concentration that will damage the building to a degree that would adversely affect its stability or the performance of assemblies separating dissimilar environments.
(2) Material that is susceptible to changes in volume due to freezing shall not be used as fill beneath floors-on-ground that will be subjected to freezing temperatures.
(3) Except as provided in Sentence (4), fill beneath floors-on-ground shall be compacted.
(4) Fill beneath floors-on-ground need not be compacted where the material is clean coarse aggregate containing not more than 10% of material that will pass a 4 mm sieve.
9.16.3. drainage