The short answer
In 2026, most decks we build in Ottawa cost between $40 and $120 per square foot, installed. That includes footings, framing, decking, standard railings and labour. A typical 300 sq ft composite deck lands around $19,500 to $30,000.
That's a wide range, so let's break it down. If you'd rather play with numbers, our deck cost estimator gives you a ballpark in about ten seconds.
Price by material
Your choice of decking is the single biggest factor in the price. Here's what each costs installed, along with how long it lasts and how much work it is to look after.
| Material | Per sq ft | Lifespan | Upkeep |
|---|---|---|---|
| Pressure-treated | $40–60 | 15–20 yrs | Stain or seal every 2–3 yrs |
| Cedar | $55–80 | 15–25 yrs | Stain or seal every 2–3 yrs |
| Composite | $65–100 | 25–30+ yrs | Wash twice a year |
| PVC | $80–120 | 30+ yrs | Wash as needed |
Pressure-treated is the budget option and still makes sense for some homes. Composite is what most of our clients choose now: it costs more up front, but there's no staining, ever. PVC is the premium choice: lighter, cooler underfoot and almost immune to moisture. Not sure which is right for you? We compare all three in wood vs. composite vs. PVC.
Price by deck size
Here's what common deck sizes cost using the ranges above, rounded to the nearest $500.
| Size | Pressure-treated | Composite | PVC |
|---|---|---|---|
| 12 × 12 ft (144 sq ft) | $6,000–8,500 | $9,500–14,500 | $11,500–17,500 |
| 12 × 16 ft (192 sq ft) | $7,500–11,500 | $12,500–19,000 | $15,500–23,000 |
| 16 × 20 ft (320 sq ft) | $13,000–19,000 | $21,000–32,000 | $25,500–38,500 |
| 20 × 24 ft (480 sq ft) | $19,000–29,000 | $31,000–48,000 | $38,500–57,500 |
As a rule of thumb, a 12 × 16 deck comfortably fits a table for six and a barbecue. If you want a dining area and a lounge area, plan for 300 sq ft or more.
Six factors that change the price
Two 300 sq ft composite decks can differ by $10,000. These are the reasons why.
1. Height and stairs
A ground-level deck needs short posts and maybe one step. A deck off a walkout basement, 8 to 10 feet up, needs bigger beams, taller posts, more bracing, longer railings and a full staircase. Height is often the biggest cost driver after material.
2. Railing style
Wood and aluminum pickets are the most affordable. Glass panels and cable railings cost noticeably more, but they keep your view open. Railings are priced per linear foot, so a long, narrow deck has more railing than a square one of the same size.
3. Site and demolition
Slopes, tight side yards, rocky ground and old decks that need tearing out all add labour. Disposal is usually its own line item.
4. Permits and drawings
Raised decks, covered decks and decks attached to the house usually need a City of Ottawa building permit. That means drawings, an application and inspections. Read when you need a deck permit in Ottawa.
5. Board details
Hidden fasteners, picture-frame borders, diagonal or herringbone layouts and premium colour lines add material and labour, and they make a big difference to the finished look.
6. Extras
Stair and post lighting, privacy walls, built-in benches, planters and pergolas are usually priced item by item. That's good news: you can add them later.
Costs people forget
- Permit fees. Separate from the build, and set by the City.
- Old deck removal and disposal. Especially for large or multi-level decks.
- Landscaping touch-ups. Grass and garden beds around the work area may need repair.
- Electrical. Outlets and hard-wired lighting need a licensed electrician.
- HST. Always check whether a quote includes tax.
How to save without cutting corners
- Keep the shape simple. Rectangles use standard board lengths and waste less.
- Mix materials. Composite on the walking surface; pressure-treated where it won't be seen.
- Re-deck a sound frame. If your structure is solid, new boards and railings can cost far less than a full rebuild.
- Phase the extras. Build the deck this year and add the pergola next year.
- Book in the off-season. Signing in late fall or winter gets you first pick of spring dates.
Want a real number for your yard? Call or text 613-806-4000 and we'll come out, measure and send you an itemized quote within 24 hours.
The Ryan's Decks crewWritten by the team that designs and builds decks across Ottawa every season.
