If the frame under your deck is solid, repairing it, or putting new boards or new vinyl on the existing frame, is usually the better value. If rot has reached the posts, beams, joists or ledger, or the deck is near the end of its life, replacement is usually the safer and smarter spend. The deciding factor is the structure, not the surface.
Start with the frame, not the boards
Every deck has two layers. The surface is what you walk on: boards or a vinyl membrane. The structure is what holds it up: footings, posts, beams, joists and the ledger board that ties the deck to your house.
Surfaces wear out first, and they cost less to replace. The structure is where the real money and the real safety risk sit. In the Lower Mainland, rain from fall to spring keeps a deck wet for months. Rot usually starts where water collects and can't dry out: at post bases, along the ledger and on the tops of joists under the boards. Shaded decks also grow moss and mildew, which holds moisture against the wood.
The good news is that a pressure-treated frame can outlast the boards on top of it, especially if it was protected with joist tape and good flashing. A tired-looking deck can still have plenty of life in its bones.
Signs your deck needs attention
Walk the deck, then look underneath it. These are the signs worth acting on:
- Soft or spongy boards. Rot in the board, and sometimes in the joist below.
- Rot at post bases. Dark, soft or crumbling wood where posts meet the footing or the ground.
- Rot at the ledger. Soft wood or water stains where the deck meets the house.
- Wobbly railings. Loose posts are a fall risk and can point to rot at the base or failed fasteners.
- Popped fasteners. Nails lifting and screws backing out. A few are routine. Lots of them can mean the boards or frame are moving.
- Vinyl leaks, bubbles or cracks. Bubbles can mean trapped water. Stains on the ceiling below mean water is already getting through.
- Mould and mildew. Surface growth washes off, but it shows the deck stays wet. Check the wood nearby for rot.
A screwdriver makes a simple test. If it sinks easily into a post, joist or the ledger, that wood is likely rotten and a builder should take a look.
What each fix involves and costs
These are typical Lower Mainland ranges before GST, for budgeting only. Real quotes depend on a site visit.
| Fix | What it involves | Typical cost |
|---|---|---|
| Small repairs | Replacing a few boards, resetting fasteners, fixing a railing | $200–800; $800–2,500 for 5–15 boards plus railing and post work |
| Post replacement | Replacing a post that has rotted at the base | $400–900 per post |
| Ledger or structural repair | Repairing the ledger, beams or a large section of frame | $1,500–4,000 for a ledger; $2,500–6,000+ for major structural work |
| Vinyl repair | Patching a tear, resealing a seam or fixing a bubble | $200–900 |
| Re-decking on a sound frame | Removing old boards and fitting new ones on the existing frame | $15–35 per sq ft in pressure-treated; $25–55 in composite |
| Vinyl re-cover | Tearing off the old membrane, then new membrane and flashing | $15–35 per sq ft; about $3,000–7,000 for 200 sq ft |
| Full replacement | Removing the old deck and building new from the footings up | $800–3,500 to demolish, plus about $35–65 per sq ft (pressure-treated) or $60–100 (composite) to rebuild |
A few things push these numbers up. Switching to composite on an old frame often means adding joists or blocking for tighter spacing, so budget $500–2,500 for frame fixes. A vinyl re-cover that needs new plywood adds about $2–4 per sq ft, and rotten joists or ledger repairs add $1,000–3,000 or more. A full replacement also needs railings and stairs, which are priced separately.
For scale, re-decking a 12x16 deck in composite on a sound frame typically runs $5,000–11,000. A brand-new 12x16 ground-level composite deck with short stairs runs $12,500–22,000. Try our deck cost calculator for your own size and material.
The age and condition rule of thumb
Age tells you how much life the deck likely has left. Condition tells you whether that matters yet. Compare your deck's age with the typical lifespans in the materials table further down, then match it to one of these situations:
- Sound frame, a few problems: repair.
- Sound frame, worn-out surface: re-deck or re-cover.
- Rot in several posts, joists or the ledger: replace.
- Old deck that needs both new boards and structural work: usually replace, since you would be paying twice to keep an ageing frame going.
One more check: new composite boards can last 25 years or more. Putting them on a frame that is near the end of its own life rarely makes sense. If repair quotes start to approach the cost of a new deck, that is another sign to replace.
Safety first: the ledger and the guards
Two parts of a deck deserve extra attention, because failure there can hurt people.
The ledger is the board fastened to your house that carries one side of the deck. Proper flashing above it is critical in our wet climate, because water that gets behind it can rot the ledger and the wall it is bolted to. If the ledger is soft or the connection looks loose, stay off the deck until a builder has checked it.
Guards (railings) are required under the BC Building Code where a deck is more than 600 mm (24 in) above the ground. For a house, guards must be at least 900 mm (36 in) high, or 1,070 mm (42 in) where the deck is more than 1.8 m (6 ft) up. Openings must not let a 100 mm (4 in) sphere through. A railing that moves when you lean on it should be fixed before anyone uses the deck again. If yours is lower or more open than this, ask about deck railings as part of the work.
When a repair needs a permit
Rules vary by municipality, and they differ more for repairs than for new decks, so always confirm with your city.
Coquitlam says repairing individual deck components, such as subfloors, surface material or guardrails, doesn't need a permit, though the work must still meet City bylaws and the BC Building Code. Port Coquitlam takes a different view: a permit is required to repair a deck, and only non-structural minor modifications are exempt. Maple Ridge also lists repair or removal of a deck as work that needs a building permit. Burnaby lists only minor non-structural exterior repairs as not needing one.
A full replacement means building a new deck, so your town's new-deck rules apply. Delta also requires a demolition permit to remove a structure larger than 10 m² and taller than 600 mm, and names a sundeck as an example. Our guide to deck permits in BC has the town-by-town picture.
Choosing materials for the rebuild
If you replace, or re-deck on a sound frame, the material you choose sets your upkeep for the next decade or two.
| Material | Installed cost per sq ft | Typical lifespan | Upkeep |
|---|---|---|---|
| Pressure-treated | $35–65 | 15–20 years | Wash yearly, stain every 2–3 years |
| Cedar | $50–85 | 12–20 years | Oil or stain every 1–3 years |
| Composite | $60–100 | 25–30+ years | Wash once or twice a year |
| PVC | $75–120 | 30–50 years | Occasional washing |
| Vinyl membrane | $45–85 | 15–20 years | Yearly check of seams, flashing and drains |
The wet coastal climate favours materials that shrug off water. Composite and PVC need no staining, but the wood frame under them still limits their life, so joist tape (about $1–2 per sq ft) is worth adding. Pressure-treated and cedar cost less up front but need regular staining, which is only practical from about May to September. If the deck sits over living space and has to be waterproof, a vinyl membrane is the usual choice; see our vinyl deck guide. For the two most popular board options side by side, read cedar vs composite decking, or browse all decking materials.
The surest way to decide is to have the frame inspected and price both options. Request free quotes and up to three vetted local builders will contact you. Ask each one to check the posts, ledger and joists, and to quote both deck repair and deck replacement so you can compare like with like.
Common questions
Can you put new boards on an old deck frame?
Yes, if the posts, beams, joists and ledger are sound. Re-decking typically costs about $15–35 per sq ft in pressure-treated or $25–55 in composite, and composite may need extra joists or blocking on an older frame.
How long does a wood deck last in the Lower Mainland?
In the wet coastal climate, pressure-treated decking typically lasts about 15–20 years and cedar about 12–20 years, depending heavily on upkeep. A well-protected frame can outlast the boards.
How much does it cost to replace a deck?
Demolition typically runs $800–3,500, and a new deck costs about $35–65 per sq ft in pressure-treated or $60–100 in composite, before railings. A new 12x16 ground-level pressure-treated deck with short stairs typically runs $7,500–14,000 before GST.
Do I need a permit to repair my deck?
It depends on your city. Coquitlam says repairing components such as decking or guardrails doesn't need a permit, while Port Coquitlam and Maple Ridge list deck repairs as needing one, so check before you start.