A simple deck is the rare home project where the same 12-by-16 rectangle of backyard can be honestly priced at $4,000 or at $11,000, and both numbers are right. So what does it actually cost to build a simple deck? The short answer: a straightforward ground-level or low deck of about 12×16 feet runs roughly $3,000 to $7,000 if you build it yourself, and $6,000 to $12,000 professionally built, with the material on top of the frame making most of the difference. The useful answer requires unpacking where the money goes, because a deck is priced by the square foot, dressed by its surface, and raised or lowered by three decisions most people make before they know they are making them.
The per-square-foot numbers, honestly framed
Deck quotes are best compared per square foot of finished surface. Across typical markets, a simple deck built by a contractor lands between about $30 and $60 per square foot all-in, while the same deck self-built costs about $15 to $35 per square foot in materials. A 12×16 deck is 192 square feet, which is how the ranges above arise: 192 feet at the DIY rates gives you the $3,000 to $7,000 band, and at contractor rates the $6,000 to $12,000 band. Larger decks cost less per foot — the stairs, permits and setup are spread wider — and small decks cost more per foot for the same reason. Height bends the numbers as well: a deck close enough to the ground to skip railings and long posts (under about 30 inches in most codes) is the cheapest honest configuration there is, which is why “simple deck” here means exactly that — low, rectangular, one level, standard stairs or a step.
What the frame costs, whatever you walk on
Roughly a third to a half of the material bill is the skeleton nobody sees: pressure-treated framing lumber, concrete and footings, joist hangers, flashing where the deck meets the house, and fasteners. Budget in the range of $5 to $10 per square foot for this layer regardless of decking choice. It is the layer where cutting corners is most expensive, because the frame decides the deck’s lifespan; a rotted or undersized frame under a premium surface is the worst of both worlds. Two frame decisions carry outsized weight. Footings must reach below the frost line in cold climates or the deck heaves each winter — digging and pouring them is the heaviest labor in the project and one reason professional quotes look the way they do. And the ledger board’s flashing, where deck meets siding, is a $30 detail that prevents a four-figure rot repair inside the house wall; no quote should omit it and no DIYer should skip it.
The surface: where the price actually gets decided
Pressure-treated pine is the economical classic at roughly $2 to $5 per square foot for the boards themselves. It asks for staining or sealing every two to three years and, maintained, serves 15 to 20 years. Cedar runs about $4 to $8 per square foot, is naturally rot-resistant and lighter to work with, and still wants regular sealing to keep its color. Composite decking costs about $8 to $15 per square foot in materials — two to three times the pine — and asks for almost nothing but washing across a 25-year-plus life. This is the decision that separates the $4,000 deck from the $11,000 one more than any other. For current product lines and colors, Trex’s decking materials and cost resources show what the composite tier includes — and note that composite also needs its specific fasteners and, often, a frame built to tighter joist spacing, which nudges the skeleton cost up too.
Wood versus composite: the 20-year math
The honest long-view comparison narrows the upfront gap. Pine costs roughly half as much on day one, then claims a staining weekend and $300 to $500 in materials every two to three years, all along a 15-to-20-year lifespan. Composite costs double on day one and then basically only asks to be washed, across 25 to 30 years. Spread over twenty years, the totals converge more closely than the quotes suggest — the remaining difference is mostly bought-back weekends. The deciding question is therefore not purely financial: it is whether the household will genuinely perform pine’s maintenance on schedule. A pine deck stained faithfully is a bargain; a pine deck neglected is a short-lived one, and composite’s premium is largely insurance against your own future laziness. Choose for the owner you actually are.
The extras that quietly double budgets
Railings are the largest: expect roughly $15 to $30 per linear foot installed, which is why a low deck that legally skips them saves thousands. Stairs beyond a simple step, a second level or story, angles and curves that waste material and demand skilled cuts, built-in benches and planters, and electrical or lighting each add their cut; combined, ambitious extras commonly raise a simple deck’s price by 50 to 100 percent. Permits, required almost everywhere, run about $100 to $500 and are not optional spending — an unpermitted deck invites stop-work orders and becomes a disclosure problem at resale. Tool reality also belongs in a DIY budget: a one-time build should rent its specialty tools (roughly $150 in rentals replaces $1,000 in purchases you will rarely repeat), while lumber prices vary by 20 percent or more between suppliers, so the materials list is worth pricing at two yards before committing.
Why quotes for the same deck differ so much
Homeowners are routinely baffled when three contractors price the identical plan $4,000 apart. The spread is not mostly dishonesty; it is hidden specification. One quote assumes footings dug to frost depth with poured concrete, another assumes precast blocks sitting on grade. One includes the ledger flashing, joist tape on the beam tops and stainless or coated structural screws; another includes nails and hope. Labor assumptions differ too — a two-person crew with a skid steer prices differently from a solo builder with a post-hole digger, and both may be legitimate. The comparison method that cuts through it is to force a written, line-item specification: footing type and depth, joist size and spacing, decking brand and line, fastener type, railing material, permit responsibility. Quotes written to the same specification suddenly converge to within a reasonable band, and the outlier — high or low — has to explain itself. The cheapest quote that omits flashing and uses shallow footings is not cheaper; it is a different, shorter-lived deck wearing the same drawing.
Where DIY stops paying
The DIY discount is real but not uniform across the job’s phases. Homeowners capture nearly all of it on the framing and decking — slow, learnable, forgiving work done at ground level. The discount shrinks or inverts on three phases: footings in rocky or deep-frost soil, where rental equipment and disposal eat the savings; any deck high enough to need engineered railing and tall posts, where errors become safety issues; and the permit-inspection sequence in strict jurisdictions, where a failed inspection costs weeks. A hybrid worth pricing is the middle path used on the interior paint math earlier in this series: a contractor sets footings, frame and ledger — the structural third — and the owner lays decking and railing, the visible two-thirds. It commonly lands 20 to 30 percent below the full professional price while keeping the structure inspected and warrantied, and it converts the DIY portion into the part of the job that is genuinely enjoyable.
The same arithmetic at other sizes
Scale the rectangle and the pattern holds, with the small-deck penalty visible at the bottom of the range. A small 8×10 stoop deck (80 square feet) runs roughly $1,500 to $2,800 DIY and $3,000 to $5,000 professionally — its per-foot cost is the worst on the table because stairs, footings and a permit are nearly the same work as for a deck twice its size. A 10×12 (120 square feet) lands around $2,200 to $4,200 DIY or $4,500 to $7,500 hired. The 12×16 worked through above sits at $3,000 to $7,000 and $6,000 to $12,000. A generous 16×20 (320 square feet) reaches $5,500 to $11,000 in DIY materials and $11,000 to $19,000 professionally built, with the per-foot rate finally relaxing. Across all four sizes, swapping the pine surface for composite multiplies the decking portion by roughly two to three, which at the large end is a bigger absolute swing than the entire frame costs. Size, in other words, is a smooth multiplier; surface is the lever.
So, the answer for a typical simple deck
Hold the design to a low rectangle at 12×16, and the answer settles: around $3,000 to $5,500 in pine as a DIY build, $6,000 to $9,000 hired in pine, and roughly double the material side if the surface is composite. Build time is two to three weekends for an experienced DIYer and about a week for a professional crew. The same discipline that keeps a deck cheap — a simple shape, few extras, honest materials — applies to its backyard neighbors, which is why it is worth reading the cheapest fence option for a backyard with the same per-foot skepticism before pricing the pair of projects together. A deck is a platform, not a sculpture; the simple version delivers nearly all of the living space at half the price of the complicated one.
