How long does a wood deck last?

A pressure-treated pine deck lasts 15–25 years with proper maintenance — annual cleaning and sealing or staining every 2–3 years. Cedar and redwood decks last 20–30 years due to their natural rot resistance, with similar maintenance requirements. Wood decks that go unmaintained (no sealing, annual standing water) can deteriorate significantly in 8–12 years, with surface checking, board softening, and fastener corrosion all accelerating together. The Midwest's freeze/thaw cycles are particularly hard on unsealed wood, as moisture absorbed into wood grain expands when frozen.

Is composite decking worth the extra cost?

For most homeowners, yes. Composite decking costs $35–$60 per square foot installed versus $15–$30 for pressure-treated wood, but eliminates annual sealing or staining requirements. Over 20 years, a wood deck owner spends $2,000–$8,000 on maintenance on a 400 square foot deck. Composite decking requires only occasional cleaning. The break-even point (when composite's total cost equals wood's total cost including maintenance) is typically 10–15 years, after which composite is the less expensive option on a lifetime-cost basis.

What are the signs that a deck needs to be replaced rather than repaired?

Replace when: (1) posts or footings are failing — a wobbly deck or posts that move when pushed sideways indicates structural compromise that is expensive to repair correctly; (2) more than 30% of the deck boards are soft, spongy, or rotted — at that threshold, replacing individual boards costs more than full replacement; (3) the ledger board (where the deck attaches to the house) is rotted or improperly attached — this is a safety issue and a significant repair; (4) the deck frame (joists and beams) shows widespread rot, not just surface boards.

How often should I seal or stain my wood deck?

Pressure-treated wood should be allowed to dry for 6–12 months before applying any sealer or stain — new pressure-treated lumber repels finishes until it dries. After the initial cure, apply a penetrating sealer or stain every 2–3 years, or when water stops beading on the surface. Cedar and redwood can go slightly longer between applications due to natural oils. In Midwest climates with significant freeze/thaw cycling, erring toward every 2 years is prudent. Signs it's overdue: surface graying and checking (fine cracks along the wood grain).

How Long Does a Deck Last? Lifespan by Material and When to Repair vs. Replace

A deck is one of the most heavily used outdoor structures on a home, and it takes more weather abuse than almost any other component — sun, rain, snow, and ice year after year. Here's what to expect from each material and how to assess whether your deck is worth repairing or ready for replacement.

Lifespan by Material

Material	Expected Lifespan	Maintenance Required
Pressure-treated pine	15–25 years	Seal/stain every 2–3 years
Cedar / Redwood	20–30 years	Seal/stain every 2–4 years
Composite (wood-plastic)	25–30 years	Annual cleaning only
PVC / cellular PVC	50+ years	Minimal
Hardwood (Ipe, Tigerwood)	25–40 years	Annual oiling

Understanding Wood Deck Deterioration

The Freeze/Thaw Problem

Midwest decks face a specific adversary that southern and coastal decks don't: repeated freeze/thaw cycling. Water absorbed into wood grain expands 9% by volume when it freezes. This expansion widens checking (surface cracks), works fasteners loose, and accelerates rot at any moisture-prone point.

The board surfaces show it first: fine surface cracks running along the grain, followed by graying, then board softening. But the real damage is often in the structure below — joists and beam ends where water collects and never fully dries.

Spring inspection priority: Check the understructure in April, not the deck surface. Soft joist ends, loose beam-to-post connections, and wobbly posts are the failure modes that matter.

Rot Patterns

Rot doesn't progress evenly. It concentrates at:

Board ends: End grain absorbs moisture faster than face grain — boards near stairs or planters deteriorate first
Ledger board connection: Where the deck meets the house — this is the most critical structural point and the most moisture-prone
Post bases: Posts set in concrete can develop rot at the concrete line; posts with post bases (metal brackets) allow air circulation and last significantly longer
Low points: Anywhere water pools rather than drains — low sections between boards, areas with blocked drainage

Composite and PVC Decking

Composite

Composite decking (wood fiber + plastic binder) was originally marketed as maintenance-free, which was somewhat inaccurate — early composite products developed mold and surface mildew that required cleaning. Modern composite products have improved significantly with capped composite construction (a full polymer wrap over the composite core) that resists mold growth, fading, and moisture.

Failure modes for composite:

Surface mold/mildew in shaded areas (older uncapped products)
Fading from UV exposure (modern products have 25-year fade warranties)
Substructure still deteriorates — composite boards on a rotted wood frame is a partial-replacement situation

Key distinction: Composite deck boards last 25–30 years; the substructure (joists, beams, posts) is typically still wood and deteriorates on a wood timeline. When evaluating a composite deck, assess the substructure independently from the decking surface.

PVC

Cellular PVC decking is the most durable decking surface available — it won't rot, won't fade, and won't absorb moisture. The tradeoff is cost ($50–$80/sq ft installed) and a slightly more plastic aesthetic than composite or wood. For homeowners who want to build once and not think about decking again, PVC is the correct long-term choice.

The Repair vs. Replace Decision

Repair When:

Isolated board rot — fewer than 20–25% of boards need replacement; individual board replacement is cost-effective
Isolated post damage — one or two posts with deterioration at the base can be sistered or replaced individually
Fastener issues — loose or corroded fasteners can be replaced without structural work
Railing failure — railings are a discrete component that can be replaced without rebuilding the deck
Ledger with minor rot — early-stage ledger rot can sometimes be addressed with sister boards and flashing correction

Replace When:

Widespread board deterioration — when more than 30% of boards need replacement, the labor cost of individual replacement often approaches the cost of full board replacement
Joist or beam rot — substructure rot is a safety issue and is rarely cost-effective to repair partially; replacing a few rotted joists almost always reveals more rot in adjacent members
Post/footing failure — a deck with failing footings (concrete heave, post rot, lateral movement) requires essentially full reconstruction
Ledger rot — the ledger is the most critical structural attachment point and the most difficult to repair correctly; significant ledger rot warrants a full rebuild with proper flashing from the start
Age + multiple issues — a 20+ year old deck with two or three simultaneous failure modes is a replacement candidate even if any single issue might otherwise be repairable

The 30% Rule in Practice

If you're assessing whether to repair or replace, walk the deck and mark every board that is soft (probe with a screwdriver — good wood resists; rotted wood gives), cracked severely, or split through. Count marked boards as a percentage of total boards.

Under 20%: repair
20–30%: get bids for both repair and replacement
Over 30%: replacement is likely the more economical choice

Then assess the structure separately. Substructure condition often makes the decision regardless of surface board percentage.

Cost Benchmarks

Project	Typical Cost
Deck board replacement (30% of boards)	$1,500–$4,000
Railing replacement	$1,500–$3,500
Post replacement (2–3 posts)	$800–$2,000
Full deck demolition and rebuild (pressure-treated, 400 sq ft)	$15,000–$25,000
Full deck rebuild (composite decking, 400 sq ft)	$22,000–$40,000