The addition of a wood deck is an easy and economical way to improve your home.
Most single level decks have the same components. However, each element will vary in size and quantity depending on the shape and size of the deck. The piers should be made of concrete, the frame that supports the decking should be a pressure-treated material and the deck boards should be cedar, redwood or some other weather-resistant lumber. We do not suggest painting deck boards, and we also feel uncomfortable about suggesting the use of pressure-treated material for any surface that will be walked on in bare feet, or that can be chewed by a toddler.
The chemical used in the pressure-treating process is a pesticide. The underside of the deck will be stronger and more weather-resistant if pressure-treated material is used. Normally, this area is inaccessible to small children.
The quality of a wood deck begins with the integrity of its concrete foundation. Although there are only a few basic types of foundations, it is a good idea to check with an engineer to make sure the type you intend to use is adequate. Deck foundations normally consist of a combination of precast concrete pier caps supported by poured-in-place concrete footers. The footer is simply a hole in the ground filled with concrete. The size and depth depends on prevailing soil conditions. Where footer dimensions will vary, the precast pier cap is a standard hardware item that is readily available. For best results, carefully level each pier cap before the supporting footer concrete dries.
The frame can consist of wood beams supported by piers or beams and piers with a layer of joist on top. Beams are used alone when there isn't enough room for two layers of framing. And, beams are more cost-effective when used without joist. Less material, less expense. Where floor joist are used at 16- or 24-inch centers, beams can be as much as 4 feet apart. We like the girder joist combination because it is stronger, but if you have a limited budget, go for beams only. Keep in mind that the deck frame will be exposed to the elements and should be assembled with fasteners that are coated to prevent rust and corrosion.
As we noted earlier, we feel good about using pressure-treated material for the framing parts. But, we prefer to use either cedar or redwood for naturally finished surfaces such as the decking and rails. However, pressure-treated southern yellow pine is OK if a painted finish is desired. Cedar and redwood contain natural resins that resist insect attack and moisture damage, and provide a luxurious natural-wood look. When lightly oiled, these materials become even more weather-resistant. If you like the knotty pine look, consider Alaskan yellow cedar. It looks like knotty pine, but is weather-resistant whereas pine is not. By the way, if redwood is the choice, consider using construction heart. It is moderately priced and reasonably knot-free.
A tip that will help to reduce rot: Wood rots when it remains wet for long periods of time and wood-to-wood connections have a tendency to retain water. Wet wood means rotten wood. Eliminate wood-to-wood connections by insulating them with strips of plastic. You can use old plastic trash bags. Siding paper or roofing felt also works. Staple a strip of the plastic or felt to the top edge of each floor joist so that the strip insulates the joist from the decking. By preventing the two wood surfaces from coming into direct contact, water retention, and accompanying wood rot, is minimized. Insulating material is not required when hidden deck fasteners are used. These fasteners not only give a clean look, they also provide a space between the joist and the decking, ensuring a connection that will dry almost as quickly as fully exposed surfaces.
When decking is installed at other than right angles to the joist, there can be as much as a 20-percent waste. We don't rule out installing decking at an angle, but we do point out that there is some additional labor and material cost involved.
Handrails are required for safety when a deck is 30 inches or more above ground. Handrails also can be used to divide (and define) areas within a deck or to separate the deck from other areas of the landscape. It is important to check the current building code when preparing to build handrails. This code tells how much weight a handrail must resist to qualify as safe. The code specifies the maximum space allowed between rail surfaces (horizontal or vertical). Remember that toddler we mentioned earlier? Well, using the proper spacing will prevent little heads from getting stuck between spindles.
If you need help constructing a deck, there are a couple of great resources that offer inexpensive planning tools. The California Redwood Association has created a deck-building kit that includes everything needed to design a deck including instructions, deck and furniture templates, graph paper, and even construction details drawn to scale. Contact the CRA by dialing (415) 382-0662.
