How much does a 12x16 deck cost in Boise?

What does a 12x16 deck cost by material and height?

Material sets the base and height moves it. The table runs 192 square feet through the same formula as our deck cost calculator: the published 2026 per-square-foot range for each material, a height factor, and a spread so you always see a range. A ground-level deck prices about 10% below a raised one in this model, and a second-story deck about 30% above it.

Two things the table cannot show: on a small deck, fixed costs weigh more per square foot. Drawings, a permit, mobilizing a crew and digging even three footings cost close to the same on 192 square feet as on 300, so a 12x16 often lands in the upper half of its range. The other is railing, stairs, old deck removal & haul-off and the other add-ons, which the calculator lists as priced at the site visit because they vary too much from yard to yard to guess.

What fits on a 12x16 deck?

A 12x16 holds one main use comfortably, or two small ones if you plan the layout. Furniture is the part people underestimate: a table is only half its footprint once chairs pull back and someone walks behind them.

• Dining for six: a 72 x 36-inch table plus about 36 inches on every side for chairs and a walkway takes roughly a 12 x 9-foot zone. On a 12x16 that leaves a 12 x 7-foot strip for a grill or two lounge chairs.
• A 48-inch round table for four: about a 10-foot circle with chairs pulled out. Set it toward one end and the other end still holds a pair of chairs.
• Lounge set: a three-seat sofa, two chairs and a coffee table want about 10 x 10 feet, which uses most of the 12-foot depth.
• Grill station: read the grill manual for its clearance to the house wall, railing and overhangs. Gas grills commonly need two to three feet behind and beside them, and the cook needs room to stand. Set it away from the door path.
• Door swing and traffic: keep a 36-inch path from the house door to the stairs clear of furniture, or every trip outside becomes a detour around chair backs.

Hot tubs are the size question we get most. A 12x16 can physically hold a mid-size spa, but the deck framing in the code's prescriptive tables is sized for a 40 psf live load, and the American Wood Council's DCA 6 deck guide states that it does not cover hot tubs. A filled spa needs engineered framing or a separate concrete pad with the deck built around it, and that work is priced at the site visit. If a spa is the main use, the 16x20 deck cost guide shows what the extra room costs.

How many footings and joists does a 12x16 need?

Most 12x16 decks attached to a house need three footings and one beam. Here is the plain-terms version for the common layout: 16 feet along the house wall, 12 feet out into the yard, with a ledger bolted to the house carrying one end of the joists and a beam on posts carrying the other.

• Joists: the 2018 IRC table (the code Idaho adopts) lets a Douglas fir-larch or hem-fir 2x8 span 11 ft 1 in at 16 inches on center, which is short of a full 12-foot run. The usual answers are 2x10 joists (13 ft 7 in at 16 inches), 2x8s at 12 inches on center (12 ft 6 in), or setting the beam about 2 feet in from the edge so the 2x8s span roughly 10 feet and cantilever the rest. The code caps a joist cantilever at one-quarter of its span or the table maximum (2 ft 1 in for that 2x8), whichever is less.
• Beam: a 16-foot beam is too long to cross in one span with dimensional lumber, so it sits on posts every 8 feet or so. In the code's southern pine column, a triple 2x12 beam carrying 12-foot joists spans 10 ft 9 in and a double 2x10 only 7 ft 4 in, which is why the beam size decides between three posts and four. The species your lumber yard stocks has its own column.
• Footings: with three posts at 8-foot spacing, the middle post carries about 48 square feet of deck (half the joist span times the post spacing). The IRC footing table, at its 1,500 psf soil column, calls for a 19-inch round or 17-inch square footing 6 inches thick for up to 60 square feet. The end posts carry about half that.
• Depth: every footing goes below Boise's 24-inch frost line, whatever its diameter.
• Free-standing option: skip the ledger and add a second beam and set of posts near the house. That means roughly six footings instead of three, more concrete and labor, but no penetrations in the house wall.

Decking direction changes the framing too. Composite boards laid straight across joists usually need 16-inch spacing, and diagonal or herringbone patterns need it tighter, so check the specific line's installation guide before you lock in a frame. Our footing depth guide covers why Boise footings are dug the way they are.

Does a 12x16 deck need a permit in Boise?

In Boise it depends on height, not size. The City of Boise requires a permit for any deck more than 12 inches above grade, which is stricter than the model code's 30 inches. A 12x16 that stays under 12 inches is exempt from the deck permit (setbacks and any HOA rules still apply), and that is the same line our ground-level price uses.

This is where the 12x16 size has an edge in Meridian. Meridian requires a permit for decks over 200 square feet, attached to the house, more than one story, or serving an exit door. At 192 square feet, a detached 12x16 that stays at or below 30 inches and does not serve a door can be exempt there, while an attached one cannot. Nampa follows Boise's 12-inch trigger. The Boise deck permit guide walks through the submittal if you are above the line.

A shade structure follows its own rules. Boise permits any attached patio cover regardless of size, while a stand-alone pergola needs a permit only above 200 square feet. A detached pergola over the full 12x16 stays under that figure; one attached to the house does not get the same pass.

What does the 12x16 price leave out?

Railing and stairs are the two lines most likely to change the total, and both depend on height. Neither is in the table above.

• Railing: the code requires a guard on any walking surface more than 30 inches above grade, 36 inches tall, with openings that stop a 4-inch sphere. An attached 12x16 open on three sides has about 40 linear feet of edge (12 + 16 + 12), less the stair opening.
• Stairs: risers can be no taller than 7¾ inches and treads no shallower than 10 inches. A deck 24 inches up needs four risers; one 48 inches up needs seven risers and about 5 feet of run. Four or more risers also need a handrail.
• Old deck removal and haul-off, if you are replacing one.
• A roof cover, pergola or low-voltage lighting.

Each of those is priced at the site visit, because the count of steps, the length of rail and the system you choose vary more than the deck itself. For railing systems and how they compare, see the deck railing cost guide.

Is a 12x16 big enough, or should you go larger?

Go by the furniture list, not the square footage. If one dining set or one lounge set is the plan, a 12x16 does the job and keeps permits and footings simple. If you want both, a grill and room to walk, the next common step is 16x20. In composite at raised height, the jump from 192 to 320 square feet moves the midpoint from about $10,500 to about $17,000 in the same model, plus more railing and possibly a fourth footing.

Board lengths are worth a look before you settle on dimensions. Many decking lines stock 12-, 16- and 20-foot boards, so a 16-foot face can run full-length boards with no butt joints. Confirm lengths for the line you pick, since a size that needs a seam mid-deck adds cutting time and a visible joint.

Getting a 12x16 quote you can compare

1. Ask each bidder for joist size and spacing, beam size and footing count in writing.
2. Confirm whether the deck is ledger-attached or free-standing, and how the ledger is flashed.
3. Get railing length, system and stair count listed as separate lines.
4. Ask who pulls the permit and whether the price assumes one.
5. Name the decking brand, line and color, not a category.

Run your own height and material in the calculator first so the bids have a reference point, then request an estimate when you want a measured number.