If you’re renovating with permits, you’ll receive building drawings. Understanding what you’re looking at prevents miscommunication with contractors and helps you verify that what’s being built matches what was approved.
The Drawing Package Components
Site plan: Bird’s-eye view of the property showing building footprint, setbacks from property lines, and location of any proposed additions. This is what the zoning review checks.
Floor plans: The horizontal cross-section of each level, showing wall locations, door and window openings, room dimensions, and fixture locations. When the drawing says “new bathroom 2.4m x 2.1m” — that’s what gets built.
Elevations: The exterior faces of the building. Front, rear, and side elevations show window and door placement, rooflines, and exterior material specifications. Critical for additions and any work affecting the exterior.
Sections: Vertical cuts through the building showing construction assembly — wall types, floor/ceiling assemblies, insulation locations. Often shows the critical framing and assembly details inspectors care about.
Details: Enlarged views of specific conditions — stair details, window sill details, roof-to-wall junctions. These tell the contractor exactly how to build specific connections.
Reading Floor Plans
Scale: Ontario drawings typically use 1:50 or 1:100 scale for floor plans. “1:50” means 1mm on paper equals 50mm in reality. A room shown as 40mm wide on a 1:50 drawing is 2000mm (2.0m) wide in reality.
Wall hatching: Different wall types are shown with different patterns. Double-line walls with dark infill are typically existing construction; lighter or different patterns show new work.
Symbols: Doors are shown as a line with an arc indicating swing direction. Windows are shown as three parallel lines in a wall opening.
When the Drawings and Reality Diverge
If your contractor is building something that doesn’t match the approved drawings, this is a problem. The permit was issued for the drawings, not for the contractor’s improvised field modifications.
Minor field adjustments (moving a non-structural wall 6" from the drawing location) are sometimes acceptable. Major deviations (omitting a structural beam, changing window sizes) require permit amendment.
Building code and permit questions are active discussions at home.renovation.reviews.
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