Structural Concrete Floors

Code requirements for constructing slab on grade or shallow foundations:

9.16.1.2. Structural Floor Slabs

  • (1) Floors-on-ground that support loads from the superstructure shall be designed in conformance with Part 4. 9.35.3.3. Small Garages
  • (1) Detached garages of less than 50 m2 (538 ft2) floor area and not more than 1 storey in height may be supported on wood mud sills provided the garage is not of masonry or masonry veneer construction.

Therefore, if a proposed structural slab on grade or shallow foundation is larger than 540 square feet, a Part 4 designed slab is required.

4.2.6. Shallow Foundations

4.2.6.1. Design of Shallow Foundations

  • (1) The design of shallow foundations shall be in conformance with Subsection 4.2.4. and the requirements of this Subsection. (See Appendix A.)

4.2.6.2. Support of Shallow Foundations

  • (1) Where a shallow foundation is to be placed on soil or rock, the soil or rock shall be cleaned of loose and unsound material and shall be adequate to support the design load taking into account temperature, precipitation, construction activities and other factors which may lead to changes of the properties of soil or rock.

4.2.6.3. Incorrect Placement of Shallow Foundations

  • (1) Where a shallow foundation unit has not been placed or located as indicated on the drawings
  • (a) the error shall be corrected, or
  • (b) the design of the foundation unit shall be recalculated for the altered conditions by the designer.

4.2.6.4. Damaged Shallow Foundations

  • (1) Where a shallow foundation unit is damaged,
  • (a) it shall be repaired, or
  • (b) the design of the foundation unit shall be recalculated for the damaged condition by the designer.

4.2.4. Design Requirements

4.2.4.1. Design Basis

  • (1) The design of foundations, excavations and soil- and rock-retaining structures shall be based on a subsurface investigation carried out by a person competent in this field of work, and one of the following:
  • (a) application of generally accepted geotechnical and civil engineering principles by a person especially qualified in this field of work as provided in this Section and other Sections of Part 4,
  • (b) established local practice where such practice includes successful experience both with soils and rocks of similar type and condition and with a foundation or excavation of similar type, construction method, size and depth, or
  • (c) in situ testing of foundation units such as the load testing of piles, anchors or footings carried out by a person competent in this field of work. (See Appendix A.)

4.2.4.2. Subsurface Investigation

  • (1) A subsurface investigation shall be carried out to the depth and extent to which the building or excavation will significantly change the stress in the soil or rock, or to such a depth and extent as to provide all the necessary information for the design and construction of the excavation or the foundations.

4.2.4.3. Identification

  • (1) The identification and classification of soil, rock and groundwater and descriptions of their engineering and physical properties shall be in accordance with a widely accepted system.

4.2.4.4. Loads on Foundations

  • (1) The foundation of a building shall be capable of resisting all loads as stipulated in Section 4.1., in accordance with limit states design in Subsection 4.1.3. or working stress design in Subsection 4.1.4. (See Appendix A.)

4.2.4.5. Differential Movements

  • (1) The foundation of a building shall be proportioned so that the estimated total and differential movements of the foundation are not greater than the movements that the building is designed to accommodate. (See Appendix A.)

 4.2.4.6. Depth of Foundations

  • (1) Except as permitted in Sentence (2), the bearing surface of a foundation shall be below the level of potential damage, including damage resulting from frost action, and the foundation shall be designed to prevent damage resulting from adfreezing and frost jacking. (See Appendix A.)
  • (2) The bearing surface of a foundation need not be below the level of potential damage from frost where the foundation
  • (a) is designed against frost action, or
  • (b) overlies material not susceptible to frost action.

4.2.4.7. Sloping Ground

  • (1) Where a foundation is to rest on, in or near sloping ground, this particular condition shall be provided for in the design.

4.2.4.8. Eccentric and Inclined Loads

  • (1) Where there is eccentricity or inclination of loading in foundation units, this effect shall be fully investigated and provided for in the design.

4.2.4.9. Dynamic Loading

  • (1) Where dynamic loading conditions apply, the effects shall be assessed by a special investigation of these conditions and provided for in the design.

4.2.4.10. Hydrostatic Uplift

  • (1) Where a foundation or any part of a building is subject to hydrostatic uplift the effects shall be provided for in the design.

 4.2.4.11. Groundwater Level Charge

  • (1) Where proposed construction will result in a temporary or permanent change in the groundwater level, the effects of this change on adjacent property shall be fully investigated and provided for in the design.

4.2.4.13. Swelling and Shrinking Soils

  • (1) Where swelling or shrinking soils, in which movements resulting from moisture content changes may be sufficient to cause damage to a structure, are encountered or known to exist, such a condition shall be fully investigated and provided for in the design.

4.2.4.14. Expanding and Deteriorating

  • (1) Where rock which expands or deteriorates when subjected to unfavourable environmental conditions or to stress release is known to exist such condition shall be fully investigated and provided for in the design.

4.2.4.15. Construction on Fill

  • (1) Buildings may be placed on fill if it can be shown by subsurface investigation that
  • (a) the fill is or can be made capable of safely supporting the building,
  • (b) detrimental movement of the building or services leading to the building will not occur, and
  • (c) explosive gases can be controlled or do not exist.

4.2.4.16. Structural Design

  • (1) The structural design of the foundation of a building, the procedures and construction practices shall conform with the appropriate Sections of this Code unless otherwise specified in this section.