Building a Freestanding Deck

Footings and beams
The soil near the foundation of a new home -- soil that was backfilled after the concrete basement was poured -- is unstable. Local codes usually require that concrete footings within 3 feet of the foundation must be 8 feet deep. To avoid the time, effort, and expense of such deep footings, this plan makes use of heavy-duty beams that rest on footings placed farther away from the house. The beams, made of three 2x10s, run perpendicular to the house and are strong enough to cantilever 3 feet past the footings. The middle beam supports both deck levels.

Framing
The decking is pressure-treated 5/4x6 laid at a 45-degree angle to the house. For proper support the joists must be spaced no more than 12 inches apart. If thicker 2x decking is used, or if the 5/4 decking is run perpendicular to the joists then the joists could be placed 16 inches apart.

Framing for the upper level rests on top of the lower-level framing and overlaps by 2 feet.

Using pressure-treated wood
Inexpensive pressure-treated lumber is used for the visible parts -- the decking, benches, and planter -- and the structural members. Many decks made of pressure-treated lumber lose their looks: The wood warps, splits, and turns an ugly gray. But with a little extra care a treated-wood deck can look great for many years.

Choose boards that are straight, dry, and free of large knots. Pressure-treated wood may twist and warp as it dries, so stack it tightly until you install it and fasten it securely. After a month or so, check to see whether any fasteners are working loose. If so, remove them and install longer fasteners.