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Deck builders handle the whole job: design and layout, drawings for the permit where one is needed, footings, framing, decking, guards and stairs. Some also build the pergola, privacy screen or built-in benches that go with it. The decisions that matter most come early: how high the deck sits above the ground, whether it attaches to the house, and which decking material you are prepared to maintain.
This page compares decking materials and footing methods, explains ledger attachment and flashing, and covers permits, guards and stairs, setbacks, utility locates, winter snow and finishing.
Deck materials compared: pressure-treated wood, cedar, composite, PVC and aluminum
Most deck frames are pressure-treated lumber, whatever covers them, because joists and beams sit closest to moisture. The choice you notice is the decking and railing, each with its own balance of looks, upkeep and heat underfoot.
- Pressure-treated wood: easy to find and to work, but it checks, warps and turns grey without a regular finish, and every fresh cut should be treated to keep its protection intact.
- Cedar: naturally resistant to decay and insects, lighter and more stable than treated lumber, with a warm colour that weathers to silver unless it is stained.
- Composite: boards of wood fibre and plastic that won't splinter or need staining, though they get hot in full sun and must be installed with the maker's fasteners and joist spacing.
- PVC: all-plastic boards that shrug off moisture, handy for low decks and hot tub areas, but they expand and contract with temperature, so gaps and fastening follow the maker's instructions.
- Aluminum: light, rot-proof decking and railing systems that let water and snow drain well, often chosen for balconies, with a cooler look and a louder sound underfoot.
Deck footings below the frost line: helical piles or concrete piers
A deck footing has one job: to stay where it was put. Water in the soil turns to ice and expands, pushing up on anything anchored too close to the surface, so a footing that stops above the frost line can rise a little each winter until the deck tilts, the stairs pull away and the ledger strains against the house. The required depth depends on the building code in force and on your soil, and the permit drawings should show it.
Both methods below work when properly sized and installed; the choice mostly comes down to access, soil and schedule. The concrete contractors page covers pouring and curing.
- Helical piles: steel shafts screwed into the ground by machine until they reach firm soil, ready to build on the same day and handy in tight yards; the installer should record the resistance each pile reached.
- Concrete piers: holes dug or augered below the frost line and filled with concrete in a tube form, often over a wider base; they take more digging and time to cure, but any experienced crew can build them.
- Soil and water: clay, fill and poor drainage all make heaving worse, and a good builder asks about them before choosing a method.
Ledger board attachment and flashing: keeping water out of the house wall
An attached deck hangs one side of its frame on a ledger, a board fastened to the house's rim joist. It is a common point of failure and a frequent source of hidden damage. The builder fastens it with through-bolts or structural screws in the pattern the design calls for, into solid house framing rather than into siding, brick veneer or a thin trim board.
Water is the other risk. Rain and meltwater run down the wall and collect behind the ledger unless flashing sends them out over it. Without flashing, the rim joist and the ledger can rot out of sight, weakening the connection and letting moisture reach the basement or the floor structure.
- Siding comes off where the ledger goes, so the flashing and membrane can tie into the wall's weather barrier.
- Flashing laps over the top of the ledger and under the siding above, so water runs out and away, never behind.
- Where the wall can't take a ledger, such as brick veneer or a cantilevered floor, the deck is built freestanding on its own row of footings beside the house.
Deck building permits, guards and stairs: Toronto and Montreal examples
Deck rules are set locally, and the height of the walking surface above the ground is usually what triggers a permit. In Toronto, a building permit is required to build a deck more than 60 centimetres (24 inches) above the ground. A lower, uncovered platform is exempt from the permit but must still comply with the zoning bylaw, and enclosing an existing deck of any size needs a permit.
Montreal handles permits by borough. Its page for Ahuntsic-Cartierville, for example, requires a permit to build or replace a deck, balcony, porch or front stoop whose floor is more than 60 centimetres above the ground, and for a floor higher than 1 metre it asks you to consult a plan designer and a borough representative before buying materials. The same page lists what to check first: distance from the lot lines, dimensions and floor height, guard height and baluster spacing, and the type of screen allowed.
Guards and stairs are safety items the building code governs in detail, from guard height and openings to steps and handrails; have the requirements for your deck's height shown on the drawings. A privacy screen may also fall under fence or zoning limits, which the fences page covers for Toronto.
Deck construction steps: setbacks, utility locates, framing and inspections
Most of the planning happens before the first hole is dug. Zoning sets how close a deck may come to the lot lines and how much of the yard structures may cover, and the rules sometimes differ for a raised deck, a low platform and a privacy screen. A certificate of location in Quebec, or a survey in Ontario, shows where the lines are.
- Design and drawings: size, height, stairs, guards and the load of any hot tub or pergola, drawn in the detail the permit office needs.
- Utility locates: public lines are marked free of charge through Info-Excavation in Quebec or Ontario One Call in Ontario before footings are dug, and private lines need a private locator.
- Footings: piles or piers laid out and installed, then inspected before anything covers them where the permit calls for it.
- Framing: ledger or freestanding beam, joists and blocking, with hangers and connectors rated for contact with treated lumber.
Snow load on a deck: designing for a Canadian winter
A deck is designed to carry snow as well as people, and the load depends on where you live, so the design follows your local code rather than a generic plan. Drifts build up against the house and snow sliding off a roof can land all at once, so keep the deck out from under the drip line where you can, and decide where shovelled snow will go. A hot tub adds its own weight on top of the snow, and the frame and footings must be designed for both.
Finishing a new wood deck: stain, sealer and first-year care
New pressure-treated lumber is often too wet to take a finish right away, while cedar can usually be finished sooner; the product label explains how to test whether the wood is ready. A penetrating stain protects against sun and water better than a clear sealer and is easier to renew than a film-forming paint, which tends to peel on a horizontal surface. Composite, PVC and aluminum need only regular washing. The exterior painting page explains stain choices and surface preparation in more detail.
Deck Construction: frequently asked questions
Do I need a permit to build a deck?
Often, especially for a raised deck. Toronto requires one for a deck more than 60 centimetres (24 inches) above the ground, and Montreal's Ahuntsic-Cartierville borough for a floor more than 60 centimetres off the ground. A lower deck may be exempt from the permit, but zoning rules on setbacks and lot coverage still apply, so check with your municipality before you start.
Should my deck be attached to the house or freestanding?
An attached deck needs fewer footings and feels part of the house, but it depends on a sound rim joist and careful flashing. A freestanding deck has its own row of footings along the wall, which avoids opening the house envelope and suits brick veneer, a cantilevered floor or an older wall you'd rather not disturb. Both are sound when properly designed.
Can I put a hot tub on my deck?
Only if the deck is designed for it from the start. A filled hot tub with people in it weighs far more than furniture, so the frame, beams and footings beneath it must be engineered for that load, and the tub needs its electrical connection made by a licensed electrician. Adding one to an existing deck calls for an assessment first.
Can I add a pergola or roof to my deck later?
Yes, if it's planned for. A pergola or roof adds weight plus wind and snow loads, so its posts need real footings rather than a fastening to the deck boards, and Toronto's permit exemption for low decks covers only uncovered platforms. Raise it at the design stage; the pergolas page covers the options.
Sources
Written by the LokalMatch editorial team. Reviewed by Zubair Afzal on September 10, 2026. How we write and check our guides