Before you pick a decking material or compare contractor quotes, get three things straight: whether a permit is required, what inspections come with it, and whether the person quoting you has actually built decks that pass them. Most disputes with deck contractors start because at least one of those was unclear from the beginning.
When a permit is required in Ontario
Freestanding ground-level decks with a walking surface under 60 cm above grade usually don’t need a permit, though municipal setbacks still apply. Cross 60 cm and a permit is required. Any deck attached to the house with a ledger needs a permit regardless of height, because the ledger connection counts as a structural modification to the building. Stairs with more than three risers also trigger the requirement.
Permit fees across the GTA run $180 to $620 depending on the municipality. Toronto calculates by square metre and can hit $620 on a mid-size deck. Most other GTA municipalities use a flat rate in the $180â$320 range. Add $150 to $400 for drawings if your contractor prepares them. On setbacks: most GTA municipalities apply the same side and rear setback to a deck as to the house, which is often tighter than homeowners expect before they finalize the footprint.
The three inspections
Deck permits in Ontario come with three mandatory site inspections. Each one has to be called in, and each one has to pass before the next phase starts.
First inspection is after footings are dug but before concrete is poured. Frost depth in Ontario is 1.2 m minimum, deeper on clay lots. The inspector checks diameter, depth, and that footing locations match the permit drawings. Pouring before the call means a mandatory re-dig.
Second inspection is after framing and ledger attachment, before decking goes down. This is the one that fails most often. The inspector looks at ledger bolt diameter, bolt pattern, edge distances (2 inches minimum from top and bottom edges of the rim joist, 2.5 inches from the ledger end), and flashing between the ledger and house sheathing. Ledger attachment is the most common cause of deck collapse in North America and the most common detail quick-quote contractors cut corners on. If a contractor can’t describe their ledger detail specifically, that’s worth noting.
Third and final inspection is when the deck is fully built: guards, handrails, stairs. Guardrail height, baluster spacing, and stair rise/run get checked at this stage.
Lumber specs
Pressure-treated lumber comes in treatment levels. Any component within 150 mm of the ground or in contact with concrete needs UC4A (ground contact rated). Above-grade components use UC3.2. Some contractors spec UC3.2 throughout to shave cost. On anything near grade or embedded in footings, UC3.2 fails inspection and rots faster.
Composite decking has become standard on higher-end GTA builds. Typical lifespan is 25 to 30 years with no annual staining or sealing. One thing most homeowners don’t know to ask: composite materials used in Ontario construction should carry CCMC (Canadian Construction Materials Centre) approval. A contractor specifying a composite brand without it creates a problem if you ever need to make a warranty or insurance claim.
Guardrail requirements (OBC 9.8.8)
Walking surface 600 mm to 1800 mm above grade: guard minimum 900 mm (36 inches). Above 1800 mm: minimum 1070 mm (42 inches). Baluster spacing must not pass a 100 mm (4 inch) sphere. Posts must be through-bolted to the frame, not face-screwed to the rim joist. Stair handrails need to be graspable: round or oval, 30 to 43 mm diameter.
What a complete quote covers
A quote that will actually survive a permit application specifies: lumber treatment level for each component, beam and joist dimensions and species, ledger attachment detail with bolt size and flashing method, footing diameter and depth, composite or PT decking product name, and permit application as a line item. If the permit isn’t in the quote, ask who pulls it. The permit holder is the one liable if the work fails inspection.
Have a quote in front of you, or a scope that doesn’t add up? Post the details here.
Top contributors earn $RENO and climb the leaderboard. Link your Solana wallet on signup: Start here
Related: Retaining walls in Ontario 2026 | Flagstone patios and walkways