Building a freestanding deck is easily accomplished with the proper tools and materials and a little instruction. This article will discuss the basic procedure for constructing a sturdy, level, durable, freestanding deck.
There are many composite decking, railing, and fencing materials currently on the market at a much higher price than ordinary lumber. The advantages of using composite materials are that they are low-maintenance, resilient, authentic in appearance and the deck will almost certainly outlive the owner. Consult the manufacturer’s specifications for installation instructions and fastener techniques for the product of your choosing. If you decide to go with wood, remember that pressure-treated lumber is required for any wooden structure that is exposed to the elements or in contact with moisture, the ground, or concrete.
Make sure you have your measurements and a layout plan for your deck before you begin. Obviously this information will vary based on your home, your backyard landscape, and how large you want your deck to be. The information in the steps following is provided without these specifics.
Step 1 - Build the Foundation with Deck Footings
The most expeditious and economical way to support the deck is with individual concrete footings. The deck frame will include vertical supports or posts (4x4 or 6x6); each post bears on a separate concrete footing. The footings are poured into 12-inch diameter cylindrical cardboard forms set in holes dug deep enough to penetrate the frost line. An anchor bolts six inches long is placed in the center of the form extending about an inch above the top surface of each footing.
A 3x3-foot (minimum) concrete pad will be needed at the base of the deck stair for the landing. Pour the pad over a four-inch layer of compacted gravel; the pad itself will need to have a thickness of four to six inches.
Step 2 - Install the Posts
The base of each post is secured to a bracket, which is anchored to the top of the footing. When the concrete has set, fasten the bracket onto the anchor bolt with a nut and a washer and secure the posts to the brackets with #8 galvanized nails. Use a level to make sure that the posts are plumb before starting work on the frame, and check them periodically to make sure they stay level.
Step 3 - Assemble the Deck Frame and Install the Decking
The decking will be supported by horizontal ribbon joists or “bands” that are bolted to the posts at the desired height. Larger decks will require cross beams that bear directly on the posts; the joists will, in turn, be supported by the cross beams. The joists will run in a direction parallel to the short dimension of the deck and will attach to the band with joist hangers.
Decking is typically available in nominal dimensions of 5/4x6 inches. The decking will be fastened onto the band joists with #16 galvanized nails or deck screws, overhanging a short distance along the perimeter.
Also layout and cut the stair stringers according to the height of your deck and regulations as far as step height, length, and width. Then, use more decking to install the treads.
Step 4 - Construct the Railing
Check local building code first before you construct the railing for any standards regarding railing height and the distance between balusters. These will vary by area and by the elevation of your deck.
For smaller decks, the posts can extend all the way up to form the end posts for the railing. The railing will consist of a top rail or cap, a bottom rail, and 2x2-inch balusters at five inches on center. The top rail is generally required to be 36 inches above the deck floor if not otherwise specified.