Deck Materials Compared: The 20-Year Cost of Ownership in Minnesota

The deck material argument is usually framed as "composite costs more up front but saves on maintenance." That is true, but the honest numbers are closer than either side claims. Here is the real math for a Minnesota deck.

Installed cost

For a 16 x 20 (320 sq ft) deck with railing:

Material	Per sq ft	320 sq ft deck
Treated pine	$30 – $50	$9,600 – $16,000
Cedar	$40 – $65	$12,800 – $20,800
Composite (capped)	$55 – $90	$17,600 – $28,800
PVC	$65 – $105	$20,800 – $33,600
Hardwood (ipe)	$70 – $120	$22,400 – $38,400

Add for: elevated decks with stairs, complex shapes, and premium railing (cable or glass railing alone can add $6,000 to $15,000). Twin Cities planning ranges.

20-year cost of ownership

Assume the 320 sq ft deck, Twin Cities climate:

	Treated	Cedar	Composite	PVC
Install	$12,000	$16,000	$22,000	$26,000
Stain/seal cycle	Every 2 yrs	Every 3 yrs	Never	Never
Cost per cycle	$900	$1,000	—	—
Staining over 20 yrs	$9,000	$6,700	$0	$0
Board replacement	$2,500	$1,500	$500	$300
Cleaning	$1,200	$1,200	$1,000	$1,000
20-year total	$24,700	$25,400	$23,500	$27,300
Condition at year 20	Rough, likely due	Weathered but sound	Good	Excellent

Read that carefully: over 20 years the totals are nearly identical. Composite is not more expensive than wood in the long run — it is just front-loaded. And at the end of the period you still have a usable deck instead of one that needs replacing.

If you DIY the staining, wood pulls ahead on cash cost — but that is roughly 25 to 30 weekends of your life over 20 years.

What each material is actually like in Minnesota

Treated pine. Cheapest, and it moves. Green treated lumber shrinks, cups, and twists as it dries through the first two summers. Wait 3 to 6 months before staining or the stain will not penetrate. Expect to replace boards along the way. Fine choice if budget is the driver and you do not mind maintenance.

Cedar. Beautiful, naturally rot resistant, stable through humidity swings, and it stays cooler underfoot in July than composite. It goes silver-grey if you let it, which many people prefer. The downside is softness — it dents and scratches.

Composite (capped). Wood flour and plastic with a protective polymer cap. Modern capped product is genuinely low maintenance and holds color. Two Minnesota caveats: dark colors get very hot in direct July sun, and composite is heavy and expands and contracts more than wood, so gapping and fastening detail matter. It also needs proper joist spacing — usually 16 inches on center, sometimes 12 for diagonal patterns.

PVC. All plastic, no organic content, so nothing to rot or grow mold. The lightest and the most stain and scratch resistant. Costs the most and some find the look less natural.

Ipe and hardwoods. Extraordinary durability and looks. Very expensive, hard on tools, and needs oiling to keep its color.

Where Minnesota decks actually fail

It is almost never the decking. It is the substructure and the connection to the house:

Ledger board attachment. The #1 cause of deck collapse nationally. It must be lag-bolted or through-bolted to the house rim joist (never nailed), and it must be flashed so water cannot get behind it. A rotted rim joist behind an unflashed ledger is a catastrophic, invisible failure.

Footings. Frost depth is 42 inches. Anything shallower will heave. A deck that has lifted away from the house or has a wavy surface is a footing problem.

Joists. Treated joists last, but the tops collect water where the decking sits. Joist tape — a peel-and-stick membrane over each joist top — costs a few hundred dollars and adds many years to the frame. It is the single best cheap upgrade in deck building.

Fasteners. Modern treated lumber is corrosive to standard fasteners. Hot-dipped galvanized or stainless only.

Practical Minnesota advice

• Build the frame right and choose decking by preference. The frame is what determines whether you have a deck in 25 years.
• Consider composite for the deck surface and cedar for the railing — you touch the railing and look at it up close, and it costs far less to maintain a railing than a whole deck.
• Avoid dark composite on a full-sun southern exposure. It gets genuinely too hot for bare feet in July.
• Snow: plastic shovel only, push with the boards not across them, no metal blades, and no rock salt on composite.
• Build season is roughly April to November; footings need unfrozen ground.