Pressure-treated lumber costs least up front but needs cleaning and a penetrating finish kept up. Cedar costs more, looks warmer and needs the same care. Composite costs the most and needs no stain, but it goes on joists spaced to its maker's guide and can get hot in full sun. Up north, the frame under any of them matters most.
What each material costs and asks of you
Our planning range for a new deck in Duluth and Superior is $45–$90 per square foot, installed with materials included: footings below frost depth, framing, decking, railing and stairs. The decking is one line inside that total; size, height, stairs and the site move it too. On upfront cost alone, the usual order is pressure-treated lowest, cedar in the middle and composite highest; your quote shows the exact spread for your deck. Upkeep tends to run the other way, so the real comparison is what you pay now against the hours or bills you'll spend keeping the surface sound.
| Pressure-treated | Cedar | Composite | |
|---|---|---|---|
| Upfront cost | Lowest | Middle | Highest |
| Routine upkeep | Wash, then a penetrating stain or water-repellent preservative on a schedule | The same finish schedule; clean gently, since the wood is soft | Wash; no stain or sealer |
| Freeze-thaw | Shrinks and swells with moisture; checks and cracks if the finish lapses | Moves the same way; the Forest Products Laboratory lists western redcedar as a naturally durable wood | No finish to fail; boards gapped to the maker's spec for drainage and movement |
| Snow removal | Metal blades scrape off finish on the shoveled path | Softer wood gouges more easily | Trex's guide says a plastic shovel may be used |
| Summer sun | Grays without a pigmented finish | Grays without a pigmented finish | No finish needed, but it can get hot; darker colors run hotter |
| Framing | Treated lumber at standard spacing | Usually treated lumber underneath | Treated lumber at the board maker's joist spacing, often closer |
If you're torn, look at who does the upkeep. The USDA Forest Products Laboratory says a wood deck can give decades of use with minimal maintenance; the one that gets skipped for a few seasons is the one that ends up on a rebuild list. Our deck staining page covers what a refinish involves.
Freeze-thaw, snow and the Northland winter
Wood decks take their hardest wear from moisture going in and out. The USDA Forest Products Laboratory's guide to deck finishes describes decks as living under weather that repeatedly shrinks and swells the wood, which opens checks and cracks, raises the grain and invites mildew and decay. Its authors go further: most decks are retired because of cracks and checks that timely finishing could largely have prevented. Snow that sits on the boards for months, then melts and refreezes, is exactly that cycle, so a Northland wood deck lives or dies by its finish.
The same guide favors penetrating finishes (water-repellent preservatives and semitransparent stains) on walking surfaces, because film-forming finishes such as paint and solid stain wear through in traffic paths and tend to peel when moisture gets behind them. It also warns that aggressive scrubbing or power washing strips wood from softer species such as western redcedar, which is why cedar gets a gentler cleaning. New treated boards with a factory water repellent may need a couple of months of weathering before they'll absorb stain.
Composite doesn't need a finish to keep water out, but it still moves. Trex's 2023 installation guide requires gaps between boards for drainage and for slight thermal expansion and contraction, and it sets different end-to-end gaps for boards installed above and below 40°F. With a building season this short, your deck may well go down on a cool fall day, so the installer has to gap for that day's temperature, not for July.
Sun, UV and heat on the boards
Summer sun is the other half of the wear. Ultraviolet light breaks down the surface of bare wood and turns it gray, and clear finishes carry no pigment to block it. The Forest Products Laboratory notes that pigment protects both the wood and the finish's mildewcide from sunlight, which is why a semitransparent stain outlasts a clear one on a south- or west-facing deck.
Composite skips the finish, but heat is the trade-off to plan for. Trex's guide says its decking can get hot in sun, as can concrete, sand and wood, that darker colors feel hotter, and that buyers in hot climates should consider a lighter color. On a deck with no shade where kids go barefoot, pick a lighter board. The same guide warns that sunlight reflected off low-E window glass can concentrate enough heat to char or slightly bow composite boards, so look at where your windows throw glare before you commit.
Joist spacing for composite decking
Composite boards come with their own framing rules, and they're stricter than many people expect. Trex's span chart calls for joists no more than 16 inches on center under its 1-inch residential boards and 24 inches under its 2×6 boards. Boards run at a 45-degree angle cut the allowed spacing by 4 inches, which puts 1-inch boards at 12 inches, and at 30 degrees the span drops to half. Every board has to cross at least three joists. Stairs are tighter still: the guide lists stringers at 12 inches on center for some profiles and 9 inches for scalloped-bottom boards.
That matters most when you want composite on an existing deck. A frame built at 24 inches on center for 2×6 wood boards has to have joists added before 1-inch composite can go on it, and the joists, ledger and footings under it have to be sound enough to justify a new surface. Our guide to repairing, resurfacing or rebuilding a deck walks through that call. Other brands publish their own spacing, and Trex says construction methods keep improving and points installers to its website for the current requirements, so the framing plan waits until you've picked the exact board.
Which decking holds up best to Northland freeze-thaw?
Any of the three, as long as the frame is right and the boards get the care their maker calls for. Wood fails from checking and rot when its finish lapses, so treated lumber and cedar need a penetrating finish kept up. Composite needs no finish but has to be gapped and fastened to its guide. Footings below frost depth, 5 feet in Minnesota and at least 48 inches in Wisconsin, protect all three from heave.
What joist spacing does composite decking need?
Whatever the board's installation guide says, which is often closer than wood needs. Trex's 2023 guide lists 16 inches on center for its 1-inch residential boards, 4 inches less when boards run at 45 degrees, and half the span at 30 degrees. Other brands set their own numbers, so choose the exact board before the framing plan is final, especially when you're resurfacing an old frame.
Does composite decking get too hot in the sun?
It can get hot enough to be uncomfortable on bare feet, and Trex's own guide says so, noting that darker colors feel hotter. Wood and concrete heat up in strong sun too. On an unshaded south- or west-facing deck, choose a lighter color, plan some shade, and keep an eye on glare from low-E windows, which Trex warns can char or slightly bow its boards.
Is composite decking worth the extra cost up north?
It is if you'd rather wash a deck than refinish one. Composite costs the most up front but skips the stripping and restaining wood needs to stay sound through freeze-thaw, and there's no finish to lapse. If you'd rather spend less now and don't mind a finishing day every few years, treated lumber or cedar with a well-kept finish holds up here too. Pricing both side by side settles it.
Planning a new deck? Call or text (715) 919-7956 with photos of the spot and rough dimensions, or send us your plans, and ask for two decking materials priced side by side. Every new deck gets a flat written quote you approve before work starts.