Composite decking installation starts with frost-depth footings, pressure-treated framing, and composite boards fastened over correctly spaced joists – built to handle freeze-thaw cycles and seasonal temperature swings year after year.
If you’re planning a new deck or replacing one that’s finally given out, the material and installation decisions you make upfront determine how that deck performs a decade from now. Get the substructure wrong, and no amount of premium composite boards saves it.
Get the spacing, permits, and fastening right, and you’re looking at 25 to 30 years with minimal upkeep. Read on to cover every step – material types, full installation process, real costs, and what separates a deck that lasts from one that doesn’t.
What Is Composite Decking?
Composite deck boards come from a blend of recycled wood fibres and plastic polymers. The result is a board that looks like natural wood but performs far better outdoors. Modern composite boards carry a protective cap layer on all four sides. This cap resists moisture, fading, scratching, and mold growth.
Three main types exist in the Canadian market:
| Type | What It Is | Best For |
| Wood-Plastic Composite (WPC) | Wood fibre + polyethylene blend | Most residential builds |
| Capped Composite | WPC with polymer shell | High-traffic, high-exposure decks |
| Full PVC Composite | 100% synthetic, zero wood content | Pool areas, extreme moisture zones |
Choosing the right type depends on your budget, exposure level, and how the deck will be used. A poolside build has different demands than a ground-level patio. The composite decking materials available for Ontario builds range from entry-level boards to fully capped premium lines – each suited to a different project scope.
Why So Many Homeowners Are Replacing Their Wood Decks With Composite?
Wood decks in Ontario’s climate often reach their limits sooner than homeowners expect. Composite decking offers a more durable, lower-maintenance alternative that performs better over the long term.
Ontario’s freeze-thaw cycles accelerate wood damage
Seasonal temperature changes cause wood to expand and contract repeatedly. Over time, this can lead to cracking, warping, heaving, and board separation. Composite decking is designed to remain more stable through changing weather conditions, helping maintain a smoother and more consistent surface year after year.
Wood maintenance costs add up over time
Many homeowners underestimate the ongoing upkeep required for a wood deck. Staining, sealing, repairs, and replacing damaged boards can cost between $3,000 and $5,000 over a 10-year period. Composite decking removes most of that ongoing maintenance and typically only requires occasional cleaning with soap and water.
Surface wear affects everyday use
As wood ages, it can splinter, fade, and develop rough spots that reduce comfort and safety, especially for families with children or pets. Composite decking maintains a smoother finish over time and does not require sanding or resurfacing.
Composite can add long-term value
A professionally built composite deck can recover a significant portion of its installation cost at resale. According to Remodeling Magazine’s Cost vs. Value Report, outdoor living upgrades continue to influence buyer interest and perceived home value.
Longer lifespan makes the investment easier to justify
Quality composite decking products often include warranties ranging from 25 to 30 years. In comparison, even well-maintained wood decks may require major repairs or replacement after 10 to 15 years, depending on climate exposure and usage.
If your existing deck has moved beyond practical repair, a complete deck replacement and removal service allows for full demolition, site preparation, and installation of a new structure built for long-term use
How to Install Composite Decking: The Full Process
Gather The Right Tools
Having the right tools on site from day one prevents costly delays and poor-quality cuts.
| Tool | Purpose |
| Circular saw – fine-tooth composite blade | Cuts boards cleanly without tearing or fraying edges |
| Impact driver and drill | Drives fasteners, hidden clips, and lag screws |
| Chalk line and tape measure | Keeps the board running straight across the full deck length |
| Speed square and carpenter’s level | Verifies framing is square and joists are in plane |
| Hidden fastener clips – brand-matched | One clip per joist, per board – must match your composite product |
| Joist tape (butyl or self-adhesive flashing) | Applied to joist tops to protect PT lumber from moisture |
| Jigsaw | Handles curves, notches, and tight cuts around posts |
| Post hole digger or power auger | Digs footing holes to the required frost depth |
| Sonotube concrete forms | Forms footings below the frost line |
| Spacers – 6 mm and 3 mm | Maintains consistent expansion gaps between boards |
| Countersink bit and pre-drill bit | Required for face screwing and end-of-board fastening |
| Safety gear – gloves, eye protection, dust mask | Composite cutting produces fine dust particles |
Use a blade rated for composite specifically. A standard framing blade tears the cap layer and leaves rough edges that compromise the finished look.
Step 1: Site Assessment and Planning
Begin with a thorough evaluation of the yard before any material gets ordered. Check the ground slope first. Your deck surface needs a slight fall of 1/8 inch per foot away from the house. This directs water away from the foundation and prevents pooling under the structure.
Inspect the ledger attachment point on the house for attached builds. The ledger must fasten to a structural rim joist – never to siding, sheathing, or fascia boards. Identify your footing locations based on the beam layout and span calculations from your structural drawings.
Then lock in your deck design and installation plan – size, shape, deck height, board direction, and railing style. Review setback requirements with the Town of Newmarket before finalizing placement. Decks must sit a minimum distance from property lines. That distance varies by lot and zoning classification in York Region.
Step 2: Permits in Newmarket, Ontario
Building permits are a legal requirement for most deck projects in Ontario. According to the Town of Newmarket Building Department, a permit is required when:
- Your deck attaches to the house
- It exceeds 10 square metres (108 sq ft)
- It sits more than 600 mm (24 inches) above grade
| Permit Detail | Newmarket / York Region |
| Typical permit fee | $200 to $500 |
| Documents required | Site plan, structural drawings, material specs |
| Inspections required | Footing stage + final completion |
| Risk of skipping | Real estate disclosure obligations at home sale |
Unpermitted structures in York Region are expensive to resolve after construction is complete. Securing the permit before breaking ground is always the right sequence.
Read More: Composite Decking Prices: Materials, Labour & Hidden Costs
Step 3: Footings and Frost Depth
Footings carry the entire structural load of the deck. In Ontario, they must extend below the frost line to prevent seasonal heaving and movement.
The frost line in Newmarket and the York Region area sits at approximately 1.2 metres (48 inches) below grade, per the National Building Code of Canada.
Two footing types work well for Ontario residential builds:
- Concrete tube forms (Sonotube): Dug to frost depth, tube form set in place, concrete poured, and a standoff post base anchor set in wet concrete before it cures. Diameter is typically 10 to 12 inches for residential load requirements. Most common across Newmarket and Aurora builds.
- Helical pile footings: Steel screw piles driven into the ground with hydraulic equipment. No digging, no curing time, and excellent load capacity in loose, wet, or unstable soils. A strong choice for East Gwillimbury and Holland Landing areas where soil conditions vary.
Allow concrete footings to cure for a minimum of 24 to 48 hours before placing posts or beginning framing. Loading freshly poured footings shifts the post anchors and compromises the footing alignment.
Step 4: Pressure-Treated Framing
Your composite boards need a structurally sound frame underneath them. Even full composite builds require a pressure-treated lumber substructure. Ontario Building Code mandates PT lumber rated for ground contact (ACQ or CA-B treatment) for any framing within 150 mm of grade. Above-ground framing uses above-ground-rated PT lumber.
Your frame consists of four structural components:
| Component | Technical Detail |
| Ledger board | 2×10 or 2×12 PT lumber bolted to rim joist with 1/2″ lag screws or through-bolts at 16″ OC. Install flashing or self-adhesive membrane behind the ledger to prevent water infiltration at the house connection. |
| Beam | Sized to span between posts based on load calculations. Double 2×10 or LVL beam is common for residential spans. Sits on standoff post caps – never embedded in concrete. |
| Joists | Typically 2×8 or 2×10 PT lumber spanning from ledger to outer beam. Set in code-approved joist hangers at both ends. Space at 16″ OC for standard composite runs. |
| Blocking | 2x blocking installed between joists every 4 to 6 feet, and at all butt joints. Prevents joist rotation and provides a nailing surface at board end joints. |
Apply self-adhesive joist tape along the top edge of every joist and beam before composite boards go down. This tape protects PT lumber from moisture accumulation at the contact point and significantly extends substructure life.
Steel framing is a premium alternative for wet-area builds. Zero rot risk, longer service life, and compatible with all composite products. For pool deck installations or builds in persistently damp areas, steel framing is worth the additional cost.
Step 5: Joist Spacing for Composite Boards
Before any boards go down, verify every joist is level and in the same horizontal plane. Set a long level or straight edge across multiple joists.
Any high points need to be planned down. Low points need shimming. Composite boards will follow the frame exactly – an uneven frame creates an uneven deck surface.
Joist spacing requirements vary based on your board layout:
| Install Type | Required Joist Spacing | Why |
| Standard 90-degree board run | 16 inches on centre | The manufacturer’s minimum for most composite products |
| Diagonal installation at 45 degrees | 12 inches on centre | A longer unsupported span requires tighter spacing |
| Picture-frame border layout | 12 inches on centre | Border boards run perpendicular, need closer support |
Install double joists at all butt joints where two board ends meet. A single joist at a butt joint creates movement over time. Double joists give each board end its own bearing surface and fastening point.
Composite boards expand and contract with temperature changes. In Newmarket’s climate, that range runs from -25°C to +35°C across the year.
Most composite products move 3 to 5 mm over that full range. Proper board-end gapping and consistent side gapping of 6 mm (1/4 inch) accommodates that movement without buckling or tight joints cracking.
Step 6: Board Installation and Hidden Fasteners
Acclimate your boards first
Store composite boards flat on site in a shaded area for at least 24 to 48 hours before installation begins. This lets boards adjust to the local ambient temperature and moisture conditions. Boards installed directly from a warm truck onto a cold frame can shift after installation.
Install starter clips along the outer edge of your first joist. Space one clip every 300 mm along the joist length. The starter clips create the correct gap at the outer board edge and hold the first board in position. Snap your first board into the starter clips and verify it is straight against a chalk line before fastening anything permanently.
For the field boards, the hidden fastener sequence works as follows:
- Insert one hidden fastener clip into the grooved edge of the fixed board, centred over each joist below
- Align the screw hole over the joist centre and drive the fastener screw – one fastener per joist per board
- Slide the next board into position so its groove seats fully over the protruding clips
- Repeat across all joists until the last two boards
Trex Hideaway clips automatically create a consistent 6 mm (1/4 inch) gap between boards. Fiberon’s Phantom system and TimberTech’s CONCEALoc clips follow the same principle. Always use the fastener system specified by your composite brand – mixing fastener systems voids the warranty.
At board ends and butt joints:
Pre-drill pilot holes within 38 mm (1.5 inches) of any board end before driving a fastener. Composite boards can crack at the ends without pre-drilling, particularly during cold-weather Ontario installs. Use one fastener per board end at butt joints – never share a single fastener across two adjacent board ends.
Pinning long boards:
For boards over 4.8 metres in length, drive a single stainless steel screw through the groove at the board’s centre point into the joist below. This pins the board at its midpoint and allows thermal expansion to move outward toward both ends rather than accumulating in one direction.
Face screwing is a practical alternative for some situations. Use minimum #8 x 2-1/2 inch stainless steel or coated composite-specific screws. Place fasteners at least 30 mm (1-3/16 inches) from the board edge to prevent splitting. Two screws per joist per board is the standard.
End caps and fascia boards complete the perimeter. Fascia boards cover the exposed rim joist and framing edges. Use brand-matched fascia fasteners driven at the correct depth to avoid surface dimpling.
Read More: PVC vs Composite Decking: Complete Comparison Guide
Step 7: Railing Installation
Railing is a structural safety component governed by the Ontario Building Code. Any deck over 600 mm above grade requires a railing system. Minimum height is 1,067 mm (42 inches) for residential decks.
Baluster spacing must not exceed 100 mm (4 inches) clear between any two balusters – this prevents a 100 mm sphere from passing through.
Post spacing has a maximum of 1.8 metres (6 feet) on centre for most residential railing systems. Closer spacing increases rigidity. Posts anchor to the deck frame – not to the decking surface. Through-bolt the post base to the header joist or rim joist using appropriate hardware rated for the post size. This connection carries the lateral load applied when someone leans against the railing.
Your railing options through our deck railing and bench installation service:
| Railing Type | Best For | Cost Level |
| Aluminum balusters | Most residential builds – durable, powder-coated, low-maintenance | Mid-range |
| Glass panels | Yards backing onto green space, water, or open views | Premium |
| Cable railing | Modern look with open sightlines, view-oriented properties | Premium |
| Composite railing | Seamless colour match to your deck board finish | Mid to high |
Through-bolt posts anchored to the joist header provide the structural strength that railing systems require under lateral load. Surface-mounted posts carry a higher failure risk and fall short of best practice for elevated deck builds.
Step 8: Finishing and Final Walkthrough
Stair installation is the final structural phase. Cut stair stringers from 2×12 PT lumber with a minimum remaining depth of 89 mm (3.5 inches) at each notch cut. Stringer spacing must not exceed 400 mm for composite stair treads.
For treads deeper than 280 mm, install a centre stringer for additional support. Land all stair stringers on a concrete pad at grade – not on bare soil or gravel. Ontario Building Code Section 9.8.4 sets the minimum stair width at 860 mm clear.
Add nosing on composite stair treads with a 25 to 38 mm overhang for code compliance and a finished appearance.
Rough-in your deck lighting wiring before fascia boards are fastened. LED post cap lights, stair riser strips, and under-rail systems all require conduit or wiring channels that are far easier to run before the perimeter is closed in. Planning lighting at this stage prevents costly rework later.
Once the build is complete, the inspector conducts a final site visit. A thorough walkthrough covers every board, railing post, stair tread, and fastener connection before the project is signed off.
Read More: 5 Reasons to Pair New Deck with New Patio Doors
DIY vs. Professional Composite Decking Installation
DIY composite deck installation is possible for experienced carpenters. The process carries more technical demand than most homeowners anticipate. A clear comparison helps set realistic expectations:
| Factor | DIY | Professional |
| Timeline (300 sq ft deck) | 3 to 4 weekends | 3 to 4 days |
| Permit submission | You handle all drawings and submissions | Handled for you |
| Frost-depth footing accuracy | High risk of errors | Guaranteed to code |
| Manufacturer warranty | Potentially voided by installation errors | Protected |
| Material waste | 15 to 20% over from mis-cuts | Minimized by experience |
| Total cost | Lower labour but higher risk | Higher upfront, lower risk |
Where DIYers most often run into trouble:
- Footings dug too shallow for Ontario’s 1.2-metre frost depth
- Wrong joist spacing for the chosen composite product – warranty voided
- Permit submission errors flagged at footing inspection
- Material over-order due to inaccurate measurements
Most major composite manufacturers require correct installation for product warranties to apply. Improper joist spacing or a failed permit inspection voids coverage on a $10,000 to $20,000+ investment.
For complex builds like elevated decks or ground-level platform builds, the structural requirements and permit process make professional installation the practical choice for most Newmarket homeowners.
How Long Does Composite Deck Installation Take?
| Deck Size | Professional Timeline |
| Small – under 200 sq ft | 2 to 3 days |
| Standard – 200 to 400 sq ft | 4 to 6 days |
| Large or multi-level – 400 sq ft+ | 1 to 2 weeks |
Weather affects the footing and framing stages most in our region. Heavy rain delays concrete pours. Ground frost in late October shuts down footing work entirely. Build realistic weather buffers into your project timeline.
Spring through early fall is the best build window in Newmarket. Starting in April or May means your deck is ready well before summer. Project slots in our area fill up quickly between May and August, so scheduling early is worth planning for.
Cost of Composite Decking Installation in Newmarket, Ontario
Composite decking installation in Newmarket runs $50 to $90 per square foot, fully installed. That covers materials, labour, footings, framing, and standard aluminum railing.
| Project Type | Estimated Cost (CAD) |
| Small ground-level deck – 150 sq ft | $7,500 to $13,500 |
| Standard attached deck – 300 sq ft | $15,000 to $27,000 |
| Elevated or second-storey deck | $20,000 to $40,000+ |
| Pool deck – composite, 400 sq ft | $20,000 to $36,000 |
What pushes your cost higher:
- Premium composite brand – Trex Transcend vs. entry-level boards
- Glass or cable railing over standard aluminum
- Stairs with multiple landings
- Helical pile footings over standard concrete pours
- Permit and inspection fees – $200 to $500 in York Region
Composite costs more upfront than pressure-treated wood, which runs $30 to $50 per square foot. Factor in zero annual maintenance and a 25 to 30-year lifespan – composite wins on total cost of ownership past the 7 to 8-year mark.
Always budget an extra 10 to 15 percent over your base quote. Unexpected soil conditions, permit revisions, and design changes happen on real builds. Planning for them keeps your project on time and on budget.
In Closing
Composite decking installation done right is a long-term investment that pays off every season – no warping, no staining, and an outdoor space that holds its value for decades. Before starting any build, confirm footing depth, joist spacing, and permit requirements are fully in order. Skipping any one of these steps shortens the life of the entire structure.
XP Decking brings 15 years of hands-on experience to every composite deck build across Newmarket and York Region. Book a free on-site estimate and get a project plan built around your yard, your budget, and your timeline.
Frequently Asked Questions
Does composite decking get hot in summer?
Composite boards absorb more heat than wood, particularly darker shades in direct afternoon sun. Lighter colour options and fully capped boards with heat-dispersing technology stay noticeably cooler underfoot during peak summer months.
Can composite decking be installed over an existing wood deck?
It is possible in limited cases, but rarely the right call. Existing framing must meet current joist spacing requirements for composite, and any hidden rot or structural weakness underneath will shorten the life of the new surface above it.
What does composite decking maintenance actually involve?
Routine care means sweeping off organic debris and rinsing with mild soap and water once or twice a season. Avoid pressure washing on high settings and metal shovels in winter – both damage the cap layer and reduce the board’s long-term stain and fade resistance.
