A 16x20 deck is 320 square feet, the size where a deck stops being a landing and becomes an outdoor room. A dining set on one end and chairs on the other both fit. The bigger footprint also means more framing and usually stairs and railing, so the number is about more than the decking now.
Example rates, worked out
| Material | Example rate | 16x20 (320 sq ft) |
|---|---|---|
| Pressure-treated | $40 / sq ft | $12,800 |
| Cedar | $50 / sq ft | $16,000 |
| Composite | $60 / sq ft | $19,200 |
Example rates only, installed. The spread between pressure-treated and composite is $6,400 on this footprint, which is the real decision the customer is making, so it is worth showing both instead of quoting one.
The parts that scale on a bigger deck
At 320 square feet you almost always have stairs, a full railing run, and more footings than a small landing needs. Stairs price per step in the calculator, so a set of them lands as its own line rather than hiding in the rate. A raised deck adds taller posts and beam work, which is labor the square footage alone will not tell you.
If an old deck comes out first, tear-out at the example $3 per square foot is $960 here plus haul-off, quoted separately.
Compare materials, run other sizes
The deck cost calculator opens preloaded at 16x20 and switches material or footprint on the spot, including the smaller 12x16 deck. For the upkeep side of the material choice see wood vs composite deck, and for the framing and stair calls see how to price a deck build.
The fastest version of this is your own rates on your own phone. PriceDesk is free for 14 days, no card.