Start with how you will use it
Before size and material, think about use. A deck for grilling and a small table can be 10 by 12 feet. A deck for dining for six plus a couple of lounge chairs needs closer to 14 by 16 or more. If the deck will hold a hot tub, the framing has to be designed for that load from the start. Note where the sun falls in the afternoon and where the kitchen door opens, since that usually decides where the deck goes.
How a deck is built
A deck has three layers. Footings carry the load into the ground below the frost line. The frame, made of posts, beams and joists, carries the surface. The decking and railings are what you see and touch. Attached decks also have a ledger board fastened to the house, which is one of the most important connections on the whole project and needs to be bolted and flashed correctly to keep water out of the house wall.
- Footings below the frost line, poured or helical
- Posts, beams and joists sized for the span
- A flashed, bolted ledger on attached decks
- Hardware and fasteners rated for treated lumber
- Decking, railings and stairs
Slopes, rock and height
Many lots in Ossining and the surrounding hills slope away from the house, and some have rock close to the surface. A tall deck needs bigger posts, bracing and longer stairs. Rock can mean pinning footings or shifting posts. Builders sometimes suggest a multi-level design that steps down with the grade, which can be easier to use and less imposing than one tall platform. Expect the estimate to reflect the height and the digging.
Permits and inspections
Most Westchester towns and villages require a permit for a new deck. That usually means a drawing showing size, height, footings and framing, a check against setbacks from property lines, and inspections, often one for footing holes and one at the end. Trusted Local Contractors reports that permits in most Westchester towns take 2 to 6 weeks. The builder should handle the application.
Questions to ask a builder
Ask what lumber and fasteners they use, how they attach and flash the ledger, how deep footings will go, what joist spacing they use for the decking you chose, and who pulls the permit. Get the size, material, railing type, stairs and price in writing, with a payment schedule tied to stages of the work.
Request an estimate
Use the estimate form. Tell us your town, roughly how big a deck you want, how high off the ground it will be and the material you are leaning toward. A local deck builder will reach out to see the yard.
New deck costs by size in Westchester
Published totals from Trusted Local Contractors, including footings, framing, railings, stairs and a basic permit, but not site prep. Not quotes.
| Deck size and material | Typical range |
|---|---|
| 12 x 12 ft, pressure-treated | about $7,000 to $12,000 |
| 12 x 12 ft, composite | about $10,000 to $16,000 |
| 14 x 20 ft, pressure-treated | about $12,000 to $20,000 |
| 14 x 20 ft, composite | about $18,000 to $28,000 |
| 16 x 24 ft, pressure-treated | about $16,000 to $28,000 |
| 16 x 24 ft, composite | about $24,000 to $38,000 |
| Concrete footing, each | about $100 to $250 |
Rounded published Westchester ranges, not quotes. Tall decks, steep or rocky sites, and premium railings cost more.
Questions homeowners ask
How much does a 12 by 12 deck cost in Westchester?
Trusted Local Contractors puts a 12 by 12 foot pressure-treated deck at about $7,000 to $12,000 and a composite one at about $10,000 to $16,000, including footings, railings, stairs and a basic permit.
What size deck do I need?
For a grill and a small table, about 10 by 12 feet. For a dining table for six plus seating, plan on 14 by 16 or larger. Walk it out with stakes and string before deciding.
Can a deck be built on a steep yard?
Yes. It needs taller posts, bracing and more stairs, and sometimes a multi-level layout that steps down the hill. Expect the price to rise with height.
Can I add a hot tub to a deck later?
Only if the framing was designed for it. A filled hot tub is very heavy. If a tub is a possibility, tell the builder before the deck is designed.
Other services
Composite decks
Low-maintenance composite and PVC decking.
Deck replacement
Tear out an old deck and build a new one.
Deck repair
Boards, joists, railings, stairs and refinishing.
Screened porches
Screen in a deck or porch, or build a new one.
Deck railings and stairs
New or replacement railings and deck stairs.