Division B
Acceptable Solutions

Part 9 — Housing and Small Buildings

Section 9.16. Floors-on-Ground

9.16.1. Scope

9.16.1.1. Application

1) This Section applies to floors supported on ground or on granular fill that do not provide structural support for the superstructure.

9.16.1.2. Structural Floors

1) Floors-on-ground that support loads from the superstructure shall be designed in conformance with Part 4.

9.16.1.3. Required Floors-on-Ground

1) All spaces within dwelling units, except crawl spaces, shall be provided with a floor-on-ground, where

a) access is provided to the space, and

b) a floor supported by the structure is not provided.

9.16.1.4. Dampproofing and Waterproofing

1) Dampproofing and waterproofing shall conform to Section 9.13.

9.16.2. Material beneath Floors

9.16.2.1. Required Installation of Material Beneath Floors-on-Ground

1) Except as provided in Sentence (2), a drainage layer shall be installed below floors-on-ground. (See Appendix A.)

2) The drainage layer required in Sentence (1) need not be installed below

a) slabs in garages, carports or accessory buildings, or

b) buildings of industrial occupancy where the nature of the process contained therein permits or requires the use of large openings in the building envelope even during the winter.

BC2012  2012-01-01 R1NC2010  2010-01-01 R1

9.16.2.1. Required Installation of Material Beneath Floors-on-GroundGranular Material

1) Except as provided in Sentence (2), a drainage layer shall be installed below floors-on-ground. (See Appendix A.)Except as provided in Sentence (2), not less than 100 mm of coarse clean granular material containing not more than 10% of material that will pass a 4 mm sieve shall be placed beneath floors-on-ground. (See also Subsection 9.13.4. and related Appendix Notes in Appendix A.)

2) The drainage layer required in Sentence (1)Granular material need not be installed belowunder

a) slabs in garages, carports or accessory buildings, or

b) buildings of industrial occupancy where the nature of the process contained therein permits or requires the use of large openings in the building envelope even during the winter., or

c) buildings constructed in areas where it can be demonstrated that soil gas does not constitute a hazard.

9.16.2.1. Required Installation of Material Beneath Floors-on-GroundGranular Material

1) Except as provided in Sentence (2), a drainage layer shall be installed below floors-on-ground. (See Appendix A.)Except as provided in Sentence (2), not less than 100 mm of coarse clean granular material containing not more than 10% of material that will pass a 4 mm sieve shall be placed beneath floors-on-ground. (See also Subsection 9.13.4. and related Appendix Notes in Appendix A.)

2) The drainage layer required in Sentence (1)Granular material need not be installed belowunder

a) slabs in garages, carports or accessory buildings, or

b) buildings of industrial occupancy where the nature of the process contained therein permits or requires the use of large openings in the building envelope even during the winter.

9.16.2.2. 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. (See also Article 9.4.4.4. and A-9.4.4.4.(1) in Appendix A.)

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. (See also Article 9.4.4.4. and A-9.4.4.4.(1) in Appendix A.)

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 coarse clean granular material containing not more than 10% of material that will pass a 4 mm sieve.

NC2010  2010-01-01 R1

4) Fill beneath floors-on-ground need not be compacted where the material is coarse clean granular materialcoarse aggregate containing not more than 10% of material that will pass a 4 mm sieve.

9.16.3. Drainage

9.16.3.1. Control of Water Ingress

1) Except as provided in Article 9.16.3.2. or where it can be shown to be unnecessary, ingress of water underneath a floor-on-ground shall be prevented by grading or drainage.

9.16.3.2. Hydrostatic Pressure

1) Where groundwater levels may cause hydrostatic pressure beneath a floor-on-ground, the floor-on-ground shall be

a) a poured concrete slab, and

b) designed to resist such pressures.

9.16.3.3. Floor Drains

1) When floor drains are required (see Section 9.31.), the floor surface shall be sloped so that no water can accumulate.

9.16.4. Concrete

9.16.4.1. Surface Finish

1) The finished surface of concrete floor slabs shall be trowelled smooth and even.

2) Dry cement shall not be added to the floor surfaces to absorb surplus water.

9.16.4.2. Topping Course

1) When a topping course is provided for a concrete floor slab, it shall consist of 1 part cement to 2.5 parts clean, well graded sand by volume, with a water/cement ratio approximately equal to that of the base slab.

2) When concrete topping is provided, it shall not be less than 20 mm thick.

9.16.4.3. Thickness

1) Concrete slabs shall not be less than 75 mm thick exclusive of concrete topping.

9.16.4.4. Bond Break

1) A bond-breaking material shall be placed between the slab and footings or rock.

9.16.5. Wood

9.16.5.1. Wood-Frame Floors

1) Floors-on-ground constructed of wood shall conform to CAN/CSA-S406, “Construction of Preserved Wood Foundations.”