Decks
From footings to railings — decks built right last 25 years. Decks built wrong collapse.
Written by Pavel Vysotckii
BCIN-certified building designer & Quantity Surveyor · Updated June 2026
Project Overview
Fixed Milestone Pricing
You approve each stage before it's paid
What is decks?
A deck is more than boards on top of joists. It's a structural system where every component depends on every other component. The footings transfer load to the soil. Posts carry the beam. The beam supports the joists. Joists support the decking you walk on. The ledger ties it all to your house. Guards keep you from falling off. Stairs get you to the ground safely. If any one of these fails, the whole thing can come down — and deck collapses cause thousands of injuries every year across North America.
Most deck failures happen for the same reasons: the ledger was nailed (not bolted) to the house, the footings were too small or too shallow, the guard posts were notched and weakened, or the wood rotted because nobody maintained it. Research from Virginia Tech and Washington State University has shown that a properly designed and built deck — with correct fasteners, connectors, and bracing — is nearly impossible to overload with people. Decks don't collapse because of too many guests at a barbecue. They collapse because they were built wrong.
In Ontario, the Building Code requires a permit for any deck more than 24 inches above grade (some municipalities set this at 2 feet or even ground level). The permit process ensures an inspector checks your footings before the pour, your framing before the decking goes on, and your guards and stairs before you use it. Skipping the permit is illegal, makes the deck uninsurable, and must be disclosed when you sell.
When you need decks
- You want outdoor living space — dining, entertaining, or a quiet spot to sit
- Your existing deck is 15-20+ years old and showing rot, loose railings, or bouncy framing
- You're replacing a deteriorated porch or front landing
- You want to add value to your home — a well-built deck returns 65-75% at resale
- Your deck was built without a permit and needs to be brought up to code
- Guard posts are loose, notched, or only nailed — this is a collapse risk
- The ledger board is pulling away from the house or shows water damage
The Process
What happens from start to finish
Design and permit drawings
1-3 weeksDesign the layout, choose materials (pressure-treated lumber, cedar, composite, or tropical hardwood), and create drawings showing footing locations, joist spans, beam sizes, guard details, and stair layout. Submit to your municipality for building permit. Include the ledger attachment detail — inspectors look at this closely.
Layout and footing excavation
1 dayStake footing locations using string lines squared off the house. Call Ontario One Call to mark buried utilities. Dig footing holes to 4 feet below grade (Ontario frost depth). Footings must sit on undisturbed soil — never on fill or soft ground. Minimum 12-inch diameter for most residential decks, but your permit drawing specifies the size.
Pour footings and set post hardware
1 day pour + 2-3 days curePour concrete into footing forms (Sonotubes or BigFoot systems). Set post bases (like Simpson ABA or PBS) into wet concrete, positioned exactly on layout marks. Level the tops. Inspector checks footing depth and diameter before you pour — don't order concrete until the inspection passes.
Posts, beam, and framing
2-4 daysCut and set 6x6 posts (not 4x4 — those are no longer recommended for most applications) on post bases. Install the beam on post caps — never notch a post to receive a beam, as this removes up to two-thirds of the wood and weakens it. Bolt the ledger to the house rim joist using 1/2-inch lag screws or through-bolts at code-specified spacing (Table 2 in DCA 6). Install lateral load connectors (minimum 3,000 lbs total). Hang joists on the beam and ledger using rated joist hangers — nails alone are never acceptable for joist support.
Flashing
Same day as ledgerInstall flashing between the deck ledger and the house. This is the most critical waterproofing detail on any deck — water getting behind the ledger rots the rim joist and causes the deck to pull away from the house. Use self-adhering membrane behind the ledger, Z-flashing above it, integrated with the house water-resistive barrier. Seal all penetrations. Caulk is not flashing.
Decking
1-2 daysInstall deck boards perpendicular to joists with 1/8-inch gaps for drainage. Pressure-treated boards should be rated UC4A or better (ground contact rated — this changed in 2016). Pre-drill near ends to prevent splitting. Leave 1/4-inch gap from the house for water drainage. For composite decking, follow manufacturer spacing and fastener requirements exactly.
Stairs
1-2 daysBuild stringers from 2x12 lumber — never smaller. Cut stringer throat must be at least 5 inches deep. Maximum riser height 7-3/4 inches, minimum tread depth 10 inches. No more than 3/8-inch variation between any two risers or treads in the same flight (uneven stairs cause falls). Stringers must be supported at top by stair brackets (not just nails) and at bottom by a concrete landing below frost depth.
Guards, railings, and handrails
1-2 daysGuard posts must be at least 4x4 and bolted through the rim joist with hold-down anchors — never just nailed or screwed. Guards must be 36 inches tall minimum (42 inches in some jurisdictions). Balusters spaced so a 4-inch sphere cannot pass. Stair handrails must be graspable (a flat 2x4 on top of the railing is not graspable) and continuous from top riser to bottom tread. Posts no more than 6 feet apart.
Final inspection
1 dayBuilding inspector checks everything: footing size and depth, ledger bolts and flashing, joist hangers and connectors, guard post attachment, baluster spacing, stair dimensions, and bracing. Fix any deficiencies and re-book if needed. Don't use the deck until it passes.
Investment Guide
Deck cost depends heavily on material choice, size, and height above grade. A ground-level pressure-treated deck is a fraction of the cost of a second-storey composite deck with curved stairs.
Pressure-treated deck (200 sq ft, low-level)
$8,000 - $15,000
Depends on: Size, footing depth, stairs, railing
Pressure-treated deck (400 sq ft, standard height)
$15,000 - $30,000
Depends on: Height, stairs, complexity, railing style
Cedar deck (300 sq ft)
$18,000 - $35,000
Depends on: Western red cedar, premium fasteners, stain
Composite deck (300 sq ft)
$25,000 - $50,000
Depends on: Brand (Trex, TimberTech, Fiberon), railing system
Second-storey deck
$30,000 - $60,000+
Depends on: Height, structural complexity, engineering, guards
Deck repair (board replacement, railing fix)
$1,000 - $5,000
Depends on: Extent of damage, material matching
Full deck replacement (tear-off + rebuild)
$15,000 - $45,000
Depends on: Size, material, existing footing reuse
What Affects the Price
Book a free walkthrough to price your deck.
Get a ballpark estimate in under 2 minutes.
Permits & Building Code
Ontario Building Code requirements
| Permit / Approval | Authority | Typical Cost |
|---|---|---|
| Building permit | Municipal building department | $200-$800 |
| ESA electrical permit | Electrical Safety Authority | $100-$200 |
| Committee of Adjustment | Municipal planning | $1,500-$3,000 |
Ontario Building Code requires permits for decks more than 600mm (about 24 inches) above adjacent grade.
Some municipalities require permits for any attached deck regardless of height — check your local bylaw.
Inspectors typically visit twice: once for footings (before pour) and once for final (after framing, guards, and stairs).
Building without a permit is illegal. You must disclose unpermitted work when selling. If there's an injury, you face serious liability.
Even if your deck passes inspection, the homeowner and builder share responsibility for ongoing safety — permits are a minimum standard, not a guarantee.
Freestanding decks (not attached to the house) still need permits if they exceed height thresholds.
Fixed Milestone Pricing, Approved by You
Every decks project runs on fixed milestone pricing. The plan is signed before work starts, and you approve each stage before it's paid.
Plan Signed Before Work Starts
Every milestone and its price is written into the contract up front — no surprise extras.
Review in the Live App
Daily photos, inspection reports, and spend vs budget land in your client app at every phase.
You Approve Each Milestone
A stage is only paid after you review the work and sign off in the app.
Project Center
Decks
Milestone Progress
Milestone 3 of 4
Deck Safety — What Most People Get Wrong
- Ledger attachment is the #1 cause of deck collapse. A ledger nailed to the house (instead of bolted) can pull away under lateral load. If your deck ledger is only nailed, fix it immediately — this is the most dangerous defect.
- Never notch a guard post. Notching removes wood at exactly the point of highest stress. Notched posts split and fail under the 200-pound load requirement. Posts must be bolted with hold-down anchors.
- 4x4 posts are not adequate for most deck applications. Current best practice calls for 6x6 posts. 4x4 posts can buckle under load, especially when tall.
- Nails are not acceptable as the sole connection for ledgers, joist hangers, stair stringers, or guard posts. Use code-rated bolts, screws, and connectors. Nails have almost zero resistance to withdrawal in the horizontal direction.
- Cosmetic maintenance (power washing and staining) does not fix structural problems. A deck that looks great on top can be rotting underneath. Inspect the underside and all connections annually.
- Concrete deck blocks sold at hardware stores are not code-compliant footings. They sit on top of the soil, don't go below frost depth, and can heave, settle, or shift. Proper footings are poured concrete extending 4 feet below grade in Ontario.
- A deck built before 2006 was likely built under a code with minimal prescriptive guidance for decks. Many decks from this era have serious structural defects that were considered acceptable at the time. Have older decks inspected by a qualified professional.
Trusted by Ontario Homeowners
One licensed crew and a live client app on every decks project
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Fixed Price
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Related Services
Concrete Works
Deck footings are poured concrete — proper footings below frost depth are the foundation of a safe deck.
Learn moreElectrical
Outdoor outlets, deck lighting, and hot tub circuits need ESA-permitted electrical work.
Learn moreHome Additions
If your deck connects to an addition or becomes an enclosed space, it falls under different code requirements.
Learn moreCommon Questions
Do I need a permit for a deck in Ontario?
How long does a deck last?
Can I build a deck myself?
What's the difference between pressure-treated, cedar, and composite decking?
My deck is old but looks fine — is it safe?
Why can't I just nail the ledger board to my house?
Why do modern treated-wood decks corrode fasteners faster than old ones?
Are all composite decking boards the same quality?
Where we do this work
Based in Toronto, working across the GTA
Ready to start your decks project?
One crew, one fixed plan, and the live app on every decks project. Daily photos, inspection reports, milestone pricing you approve — and a written warranty.