Do you need a soils report for your building permit?
Houses, additions and larger buildings: how the National Building Code and your municipality decide whether a geotechnical report is required, and the site conditions that usually trigger one.
There is no single national answer. Building codes are adopted by each province and territory, most of them based on the National Building Code of Canada, and they are enforced by the municipality's building department. Whether your permit needs a soils report depends on the type of building, the site and local rules.
Houses and small buildings
Houses and small buildings are generally designed under Part 9 of the building code. For ordinary soils, Part 9 allows foundations to be sized from prescriptive rules, without a full geotechnical investigation. The code and the building official can still require a design by an engineer when the soil is unknown, weak or unusual.
Larger buildings
Larger buildings, and buildings designed under Part 4 (structural design), need foundations designed by an engineer on the basis of a subsurface investigation. In practice, a soils report is part of the permit package for most commercial, multi-unit and institutional projects.
Site conditions that often trigger a report
- soft or sensitive clays, peat or organic soils;
- fill, old foundations or unknown material on the lot;
- a high water table, springs or a site prone to flooding;
- slopes, ravines or riverbanks, where stability must be checked;
- soils that swell and shrink with moisture, or ground affected by frost or permafrost in northern regions;
- a design with a deep basement, retaining walls or heavier loads than a typical house.
Some municipalities also map areas where a geotechnical report is always required, for instance near slopes or on known soft soils. Ask the building department early, before the house plans are final.
Additions and renovations
A new addition, a second storey or a basement lowering adds load to existing foundations. If the original soil conditions are unknown, or the house already shows settlement, the designer may ask for a geotechnical review before the permit. See cracks and settlement.
What to ask the building department
- Is a soils report required for this project and this lot?
- Does it need to be sealed by a P.Eng. licensed in the province?
- Will an inspection of the foundation excavation by the engineer be required during construction?
Then describe your project in the form: geotechnical firms in your area get back to you. You can also read what a soils report contains.