Patio Roofs
One of the most popular shade structures is a simple patio roof. Its construction can be quick and inexpensive. Whether the roof is attached to the house or standing free, the basic framework is the same: posts, supporting beams, and rafters. The type of patio roof you choose determines how sturdy the framework must be and how far apart the rafters will be spaced.
If you want a lightweight, easy-to-install roof that admits diffused sunlight, consider plastic shade cloth over widely spaced rafters. In most climates it is more useful to soften sunlight on plants than to provide shade for people. You may have noticed shade cloth used at nurseries to shade areas for flats of seedlings or other tender plants. In its simplest form it looks like colored window screening. Available in several densities, it cuts out about half to three-quarters of the sunlight. Sometimes the nursery or garden supply store that sells it can tape edges and install grommets to your specifications. Or you can secure it with wood battens. Leave a slight sag to allow for some shrinkage. Advantages are durability, light weight, and low cost. A special advantage, if you want only a seasonal roof, is that shade cloth can be easily removed and stored.
Other patio roofs that are easy to remove from rafters and to store are woven reed and woven bamboo. They look more natural than shade cloth and cast an attractive mottled shade. Like shade cloth they are relatively inexpensive. Woven reed lasts up to four years and bamboo five years or longer, if bound by wire rather than cord.
Also removable is canvas, many people’s favorite patio roof for its attractive looks and easy adaptability to many styles. A disadvantage for plants is the fact that it blocks out direct sunlight, and a disadvantage for both plants and people is the reduced air circulation. However, you can devise a design that allows the canvas to function like a window shade, opening and closing easily. Other designs also permit the free flow of air. Canvas is one of the least durable materials, but is fairly inexpensive and one of the simplest to replace.
Fiberglass and plastic panels are other inexpensive materials for roofing a patio, but they aren’t easily removed for seasonal storage. An advantage that they share with canvas is providing privacy from overhead windows, especially desirable in an urban garden. Unlike canvas, they admit light and heat. In fact, they trap heat and create a greenhouse effect. By the same token, however, they are a poor choice for a hot south- or west-facing patio, as they gather too much heat and inhibit air circulation.
Wood, in various forms, is the most popular covering for outdoor living areas, largely because it permits air circulation. It can be relatively inexpensive—lath, lattice, and grapestakes; or moderately to quite expensive—wooden overhead structures whose size and spacing can vary considerably. If you choose wooden overheads (often 2 x 3s or 1 x 2s, laid on edge), remember that not only their spacing but also the direction they are laid determines how much shade they create. For most shade plants, the lath should always be laid north-south so the bars of sunlight move across the plants. Sunlight from lath that is laid east-west moves slowly and can scorch many delicate plants.
Instead of making a patio roof entirely of wood, give some thought to minimizing the wooden structure and planting vines to cover it entirely or partially. But be sure the structure is strong enough to support the weight of a rain-dampened vine in full leaf. Some vines are fast-growing and provide shade within a season.
