Footing: at least 0.41 m2 (about 640 x 640 mm square, 25 x 25 in), at least 250 mm thick. Post: wood not less than 140 x 140 mm. Foundation depth: 1.2 m below finished ground.
Inputs: house, soil Stiff clay 150 kPa or firm clay 75 kPa, supported joist length 3.05 m, 1 floor, column spacing 3.05 m.
Footing area basis: Table 9.15.3.4.: 0.40 m2 for 1 floor supported at 3 m spacing, adjusted in proportion to your spacing of 3.05 m (Article 9.15.3.7.). Computed 0.41 m2, rounded up to 0.41 m2.
Footing thickness: not less than the greater of 100 mm and the projection of the footing beyond the post (Article 9.15.3.8.); for a 140 mm post that is 250 mm.
Post: wood posts not less than 140 x 140 mm or 184 mm round (Article 9.17.4.1.); or a steel pipe column of at least 73 mm outside diameter and 4.76 mm wall with 100 x 100 x 6.35 mm end plates (Articles 9.17.3.1. and 9.17.3.2.). The post sits centred on the footing (Article 9.17.2.1.) and is separated from concrete in contact with the ground by polyethylene film or roll roofing (Article 9.17.4.3.).
Foundation depth (Table 9.12.2.2.): 1.2 m below finished ground. The code states no frost depth for each city, and this tool does not invent one; the municipality sets the depth of frost penetration for your site. Where the table says below frost, ask the building department for the number.
Note: The table is written for column spacing of 3 m. Article 9.15.3.7. allows proportional adjustment for other spacings.
Limits: stable soils of at least 75 kPa, spread footings for wood-frame buildings of up to 2 storeys (Article 9.15.1.1.). The footing basis for decks is the 2.4 kPa load over 75 kPa; a municipal deck guide publishes the same figures. Hot tubs, roofs and heavy loads are outside this tool.
Source: 2024 Ontario Building Code (O. Reg. 163/24), Division B, Articles 9.15.1.1., 9.15.3.3. to 9.15.3.8., 9.4.2.3., 9.4.4.1. (Table 9.4.4.1.), 9.12.2.2. (Table 9.12.2.2.) and 9.17.1.1. to 9.17.4.1.
Tool: https://timberrframing.com/post-and-footing-size-calculator/
Free quote: https://timberrframing.com/contact/
Preliminary planning only; the designer or engineer of record and the building permit set govern.