How much does a deck cost?

A whole deck, added up

Most deck prices you'll come across are for the platform: the footings, posts, beams, joists and boards. Nobody can use a raised deck with only that. Here's a 12 × 16 deck, 30 inches off the ground and against the house, with railing on the three open sides and four steps down to the yard:

The railing and stairs add $1,880 to the pressure-treated deck. That's a large part of the gap between the number in an ad and the number on a quote. The deck cost calculator does this same sum for your own size.

What it costs by size

For the platform alone, at the same prices:

In this table the cost climbs in a straight line, because it's a price per square foot. Real quotes bend a little at both ends. A small deck costs more per foot, since the crew still needs a truck, a day of digging and a trip for the inspector. A very large one may need more beams and posts than the square-foot price allows for.

The four things that move the price most

Height. Once a deck is more than 30 inches off the ground, the model code wants a guard along the edge, as our guide on railing height explains. Stairs grow too. A riser can be no taller than 7¾ inches, so a deck 8 feet up needs at least 13 steps. At $150 a step in wood that's $1,950, compared with $600 for the four steps in our example.

Boards. The frame underneath is treated lumber either way, so this is the one big line you choose on looks and upkeep alone. Going from treated pine to composite, with a matching railing and stairs, adds $4,360 to the deck above.

Shape. Every corner in the outline means another railing post, more cuts and more waste. Diagonal boards cost more than the cutting suggests, because standard wood boards laid on a diagonal need joists 12 inches apart instead of 16. Our guide on joist spacing has the numbers.

The ground. A slope means longer posts on one side. A back yard the crew can only reach through a side gate means carrying everything by hand. In cold climates the footings usually have to go below the frost line, so the holes are deeper.

What quotes often leave out

None of these are hidden on purpose. They're just easy to assume someone else is covering:

• The permit. Fees vary by town, and an attached deck needs a permit under the model code. See do you need a permit for a deck.
• Taking out the old deck. Demolition and the dump fee are often a separate line, or missing altogether.
• An electrical outlet. Anne Arundel County, Maryland, for one, reminds builders that a deck within 4 inches of the house needs an outlet you can reach from the deck, under the National Electrical Code. If you don't have one out there, that's a call to an electrician.
• The extras. A gate at the top of the stairs, lattice around the bottom and lights all get added later and rarely get budgeted.
• The first coat of stain. New pressure-treated boards have to dry before they'll take stain, so the first staining usually falls outside the build. Our guide on staining a deck covers the timing.

Then there's the cost to keep it

The bill doesn't stop when the deck is finished. A wood deck needs washing and staining every few years, and a composite one mostly needs washing. So the cheapest deck to build isn't always the cheapest to own. The composite vs wood calculator runs both for 20 years, and our guide on how long a wood deck lasts shows what looking after one involves.

How to compare bids

Two deck quotes can be thousands of dollars apart and both be fair, because they aren't pricing the same deck. Before you compare the totals, ask each contractor to put these in writing:

• The board, by brand and line if it's composite.
• The frame: lumber size, joist spacing, and the size and depth of the footings.
• How the ledger is fastened to the house and how it's flashed.
• The railing: material, height and the feet included.
• The number of steps, and whether they end on a pad or on the grass.
• Who applies for the permit and who removes the old deck.
• When each payment is due. Tying payments to the footing, framing and final inspections keeps some money in your hands until the work has passed.

Fair questions

How much is a small deck, say 10 × 10?

About $3,600 in treated pine or $5,600 in composite for the platform at our prices, before any railing or stairs. Use the calculator to add those.

How much would I save building it myself?

Labor is about 51% of the pressure-treated deck in our example, so there's real money in it. Against that, you'll be paying for tools, and your mistakes come out of your own pocket. A low, freestanding deck is a far easier place to start than one bolted to the house.

Is there a size that avoids a permit?

Under the model code, a deck of 200 square feet or less can go without a building permit, but only if it's also low, detached from the house and not on the required way out. Many towns change that rule, so ask yours.

Could I just replace the boards?

If the frame is sound, yes, and it costs far less than a new deck. The deck resurfacing calculator prices it and explains how to check the frame first.

Sources

• International Residential Code, Section R105.2: the model list of work that needs no building permit, including fences up to 7 feet and small detached decks. States and cities adopt it with their own changes.
• Anne Arundel County, Maryland, Deck Construction Guide: a county guide to the 2021 IRC, with its joist span, overhang and decking tables for southern pine.
• American Wood Council, DCA 6: Prescriptive Residential Wood Deck Construction Guide: ledger attachment, joist spans, guards and stairs for wood decks.
• International Residential Code: sections R312 (guards), R311.7.8 (handrails) and R507 (decks). Your city or state adopts and amends it, so check the local version.
• How we calculate: every suggested price behind this calculator, with the date it was last reviewed.