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OBC DIVISION B · PART 9 · SECTION 9.27 — CLADDING

How far above the ground does siding have to be in Ontario?

The bottom of most cladding must be kept at least 200 mm (8 in) above finished ground level. This clearance protects siding from moisture damage caused by rain splash, snow piling and soil contact.

Code reference
Cladding must be held clear of finished ground, generally not less than 200 mm, to protect it from moisture from splash-back, melting snow and ground contact. Materials unaffected by moisture may qualify for reduced clearance, and the foundation wall exposed below the cladding must itself resist moisture and physical damage.
OBC Division B, Subsection 9.27.2.

Paraphrased for clarity — open this provision in the BUILDAiD Library for the exact wording.

What this means in practice

The 200 mm rule is one of the most frequently violated details in landscaping and regrading projects. New homes usually pass, but when owners later add soil, mulch, patios or interlock, the clearance shrinks or disappears, leading to rotted sheathing, insect entry and staining, and it can void siding warranties. When planning final grade, coordinate early: the code also wants grade sloped away from the foundation for drainage, so the siding line, top of foundation and finished landscape all have to be designed together, not fixed afterward.

Plain language

Keep about 20 cm (8 inches) of foundation visible between the ground and the bottom of your siding. If soil or mulch gets piled against siding, splashing rain and dampness will rot it from the bottom up.

Related questions

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This page is provided for general information. Building code requirements depend on your specific project, occupancy and municipality, and code editions change. Always verify requirements against the current Ontario Building Code and confirm with your local building department.