Before you race to the local lumberyard or home improvement store, attend to the following details first. You need to make some decisions before you even pull out the tape measure.

Where will I locate my deck?

Most decks are attached to the rear or side of the house, often just off the kitchen or dining area. For a small house or a first deck, this location makes the most sense because it extends your eating and entertaining area. You can also build a freestanding deck out in the yard, though it’s not as easy to access. Observe the amount of sun and shade your proposed deck will receive. A north-side location will probably mean less direct light, though you can offset that with landscape or exterior lighting. Such a location may also be exposed to winds and seasonal chills; you’ll be less likely to tarry in the spring and fall on such a deck. Siting the deck on the south side, however, is also less than inviting because this location is subject to extreme summer heat, especially if there’s no wind circulation or tall trees to provide shade. Often there’s really only one logical spot for your deck. If it’s less than ideal, don’t despair: You still can make it an inviting outdoor room with a little extra effort. If it’s directly in the line of sight of the neighbors’ deck, for example, you might consider adding privacy panels. Or build an attached pergola with lattice walls for climbing vines; the greenery will screen the view and provide welcome shade. Your problem solving is limited only by your design ingenuity.

How big should I make my deck?

Keep it in proportion to your house—and your construction skills. Some builders recommend that a deck should be as large as the largest room inside the house (typically the living room). Here’s another tip: most decks are built in increments of 2 feet. That’s because building materials are usually sold in even lengths of 8, 10, or 12 feet or longer. Check the cost per linear foot of the lumber you’re considering; typically 12-foot boards are the most cost-effective. In other words, the cost per linear foot of a 12-foot board is likely to be several cents less than the cost of either an 8-foot or a 16-foot board. When you’re buying a lot of lumber, this cost savings can be significant, and it’s the reason the average deck is 12x24 feet. If you dream of an elaborate, multilevel deck but have neither the funds to hire the work done nor the skills to make it yourself, remember that you can always start small. Plan the complete project, but build only the first level this year; add the other tiers in subsequent years.

What are the restrictions on this project?

As with most remodeling projects, first you’ll need to check local building codes, regulations, and restrictions. You’ll probably have to get a building permit from your local building department. Also call utility companies to identify the locations of underground lines. Buried cables will affect where you place your footings, while overhead cables may interfere with a sunshade. Lot restrictions may limit how close your deck can get to neighbors’ properties, and the location of a well, septic tank, or drain field may affect where you place your deck in relation to your house.

What am I forgetting?

You’d be surprised at the little details you need to consider before you can actually begin the deck. For instance, if your house doesn’t offer immediate access to the deck location, you’ll want to install a sliding door or pair of French doors—something that gives you a view of your new outdoor room and opens directly onto it. It’s generally best to install the door before the deck. You’ll also want to consider other deck access points. Besides the one from the house, there’s typically one or more from the yard. You’ll need steps for yard access, perhaps even a patio to form a transition between the deck and the yard. Naturally, you need to consider railings and built-in seating, too. And you may want to think about incorporating a planter box or two, or even a water garden. Careful planning now will make it easier to integrate all the elements into one cohesive, attractive whole.

Posts. Use 4x4s for posts up to 8 feet tall and 6x6s for posts taller than that.Decking. Check with local ordinances, but most codes require that decks support at least 40 pounds per square foot. To achieve that, if you’re using 2x4 decking, your joists should be placed 24 inches apart. If you purchase wider deck boards, such as 2x6s, you can plan 36 inches between joists.Joists. The heftier the lumber you use for joists, the longer the joists can span between supports, based on how close the joists are to each other. For instance, 2x6 joists spaced 24 inches apart can run 6 feet between supports; 2x10s, on the other hand, can span 10 feet when spaced 24 inches apart. Heftier lumber will cost more, but it can cut construction time and save on hardware costs. A good book about deck building can further clarify this concept.Lumber sizes. Be aware that lumber actually has two sizes: its nominal size (such as 2x4), and its actual size (a 2x4 is actually 1-1/2x3-1/2 inches). When you’re graphing out your deck, draw in the nominal size; when you’re estimating for materials, think in actual size. Figure the square footage of your deck (width multiplied by length). For 2x4 decking, multiply by 3.2 to get the approximate linear board feet you need; divide by the length of boards you will purchase, such as 8, 10, or 12 feet. The result is the number of boards you will need for decking. If you’re using 2x6 boards, multiply the square footage by 2 instead of 3.2.Hardware. Decks consume nails by the pound. For every 40 square feet of deck, plan to use at least 1 pound of 16d common nails for joists and 2 pounds of galvanized spiral nails, which stay down better than regular nails. Buy a few extra pounds for insurance. If you’re not planning to seal your deck, use wood screws instead of nails; they’ll cost considerably more but will hold down the boards better should the wood begin to warp over the years.