Hiring a Deck Builder in Ontario: What to Know Before You Start

Pressure-treated wood or composite: the real trade-offs

Pressure-treated wood remains the most common decking material in Ontario because it is familiar, generally less expensive up front, and easy for most builders to source and work with. It does require regular maintenance, typically cleaning and restaining every couple of years, to hold its colour and resist checking and splintering. If you are comparing the ongoing upkeep, our guide on deck and fence staining at our homeowner guides covers what that maintenance actually involves.

Composite decking, made from a blend of wood fibre and recycled plastic, generally costs more per square foot up front but requires far less annual maintenance, no staining, and tends to resist fading and splintering better over time. The trade-off is a different feel underfoot for some homeowners, and composite can run hotter in direct summer sun than lighter-coloured wood.

• Pressure-treated wood: lower material cost, needs periodic staining or sealing, classic look, widely available
• Composite: higher material cost, minimal annual maintenance, consistent colour over time, various board profiles and colours
• Both materials need a structurally sound frame underneath, the frame is usually still built from pressure-treated lumber even under composite boards
• Ask your builder which material they have the most recent experience installing, technique and fastener choice differ between the two

Ontario Building Code guard and railing rules

Deck guards are not optional once a deck surface reaches a certain height above grade, and getting this wrong is one of the more common problems inspectors flag. Under the Ontario Building Code, a guard is generally required once the deck surface is more than about 60 centimetres, roughly 24 inches, above the ground below it.

Minimum guard heights then depend on how high the deck sits. For lower decks the minimum is commonly cited around 900 millimetres, while for decks with a greater drop, generally above about 1.8 metres, the required minimum climbs to roughly 1070 millimetres. These figures are general guidance and can vary by specific condition and municipal interpretation, so always confirm the exact requirement for your project with your municipality or your builder before finalizing a design.

• Guard spacing between balusters is also regulated, generally to prevent a small child from passing through, confirm the exact spacing requirement locally
• Stair guards and handrails have their own separate requirements distinct from the main deck guard
• A builder experienced with current code should be able to explain these numbers without hesitation, if they cannot, that is worth noting

Footings and frost depth

A deck that looks fine in its first summer can start to heave, tilt, or crack at the footings within a couple of winters if the footings were not placed below the frost line. In much of Ontario, frost depth is commonly cited around 1.2 metres, roughly 4 feet, but this varies by region and even by specific municipality, so it is not a number to guess at.

1. 01

   Confirm local frost depth

   Ask your municipal building department for the exact frost depth requirement in your area before footing depth is finalized.

2. 02

   Match footing size to load

   Footing diameter and depth should reflect the deck's size, height, and the soil conditions on your property, not just a standard number used everywhere.

3. 03

   Inspect before backfilling

   Most municipalities require a footing inspection before the holes are filled, do not let a builder skip this step even if it slows the schedule.

Freeze-thaw cycling is the real mechanism at play here. Water in the soil around a shallow footing freezes and expands each winter, and over repeated cycles that movement can lift or shift the footing enough to throw the whole deck structure out of level. Getting the depth right the first time avoids a repair that is far more disruptive than the original build.

Permits: when you need one and why it matters

Most municipalities in Ontario require a building permit for a deck once it exceeds a certain height or size, though the exact thresholds vary from one municipality to the next. Some smaller, low platforms may be exempt, while a deck attached to the house at a meaningful height almost always needs one.

• Check with your local building department before design work is finalized, not after
• A permitted build includes inspections at key stages, footings and framing typically, which catches problems before they are buried or covered
• Unpermitted decks can complicate a future home sale, since buyers and their lawyers often ask for permit records
• A reputable builder will factor permit time into your project timeline rather than treating it as an afterthought

Ask your builder directly whether they are pulling the permit or expecting you to. This should be spelled out in the written scope of work, along with who is responsible for any fees. Our guide on contractor red flags covers what it means if a contractor pushes back on getting a permit at all.

What actually affects the build timeline

Deck timelines get thrown off by a handful of predictable factors, and knowing them ahead of time helps set realistic expectations with your builder.

• Permit processing time, which can range from days to several weeks depending on your municipality's current volume
• Weather, since concrete footings need proper cure time and heavy rain can delay excavation and pours
• Material availability, particularly for specific composite colours or profiles that may need to be special ordered
• Design complexity, multi-level decks, built-in seating, and pergola structures all add build days
• Inspection scheduling, since your municipality's inspector availability is outside your builder's control

Get multiple quotes and ask each builder for a realistic timeline range rather than a single optimistic number. A contractor who gives you a specific, hedged answer that accounts for permits and weather is generally more trustworthy than one who promises an unrealistically fast turnaround.