Aside from a sturdy structure and strong railings, good lighting is a deck's most important safety feature. But properdeck lightingis about more than just safety. The right lights in the right spots can make a deck better looking and more enjoyable. The best deck lighting considers all three kinds of light: essential, targeted, and ambient. Essential lighting is what's required by code at doors and stairs. Targeted lighting is for specific tasks, such as grilling or eating. Ambient lighting creates an inviting space and brightens dark areas.
There are two spots on a deck where building codes require lighting. For security, the International residential Code (IRC) requires a light near every exterior door with grade-level access. This light allows you to see visitors before you open the door. If you're installing a door adjacent to a deck that has access to grade, you'll need to include a light with a wall-mounted switch. The code also requires that stairways be well lit; unfortunately, the IRC's language is cumbersome. In simple terms, it calls for a fixture at the top landing of every stairway and for a "means to illuminate" the whole stairway.
For a deck with stairs near the door, a single bright light may be enough to illuminate both the stairs and the entry. When the stairs are farther from the door, you'll have to light these areas separately. Stairways must be at least 36 in. wide, so nonrecessed, post-mounted lights may create a code violation on narrow stairs. Keep in mind that according to the IRC code even a single step between two parts of a deck is a stairway and so is subject to stair-lighting requirements.
A deck's food-prep area should have at least one light aimed at each workspace. To better set the mood after the cooking is done, these lights should be switched separately from general lighting. The greatest difficulty in illuminating a grill is finding a spot overhead to mount the light. One common solution is spot lighting in the home's soffit, but shadows from the chef or from the grill lid can be problematic. A better choice is flexible grill lights, which are available from several manufacturers. These lights can be mounted on a wall or installed on a guardrail.
Lighting for a deck's dining area is best installed where it can illuminate the area without shining in peoples' eyes. A logical spot is on a roof or trellis over the table, where a light can also be a decorative centerpiece. Roof or trellis mounting makes it easy to tie the lights into the house's 110v power. Using that power source also makes a ceiling fan a possibility, provided it's rated for outdoor use. For ambience, dining lights should be less bright than kitchen lights and on a dimmer. Without a trellis or a roof over the table, select a lightweight low-voltage system that hangs from an umbrella or shade frame.
Compared to that of indoor spaces, adeck's ambient lightingis less intense and more dispersed. It's good for filling in where code-required and targeted lighting leave off. Ambient lights can be built into the railing, attached to balusters, or installed in the floor. Many of these lights add an attractive design element on their own.
Line Voltage vs. Low Voltage
Line-voltage outdoor lights run off the same power that's used inside the house, but the fixtures and wiring methods must be approved for outdoor use. Line voltage is the right choice for switched lights near the patio door and for ceiling fans over outdoor dining tables. For other deck lighting, the conduit and watertight boxes make line voltage more difficult to install and hide.
Low-voltage lighting fixtures are more forgiving to work with, more flexible to install, and generally safer than line-voltage fixtures. Low-voltage lighting circuits start with a transformer that reduces 120v line voltage to safer and easier-to-install low voltage (12v to 30v). Many high-quality transformers have multiple taps of various voltages. Higher-voltage taps are used to prevent dimming caused by voltage drop on long runs. Transformers range from 45w home-center versions ($35) to 1800w underground models ($1600). Many transformers are controlled by a timer or photo cell that turns the lights on and off automatically.