An attached pergola is an open lattice trellis that uses the wall of a building to support two of its four corners. The other two corners of the pergola are supported with beams. The difference between an attached pergola and a detached pergola is that the detached pergola is a stand-alone structure, similar to a gazebo. Pergolas add interest and definition to an outdoor space and often improve the value of the property. They are common on decks and patios, since they take up less space than a detached pergola.
Typically, the latticework on a pergola is simple, with beams laid perpendicular to each other. A second layer of beams can be added on top for a variation on the traditional structure. Most pergolas are square or rectangular. It is possible to construct curved attached pergolas, but they are more difficult to design and not as common.
Pergolas can be made from wood or vinyl. Wood requires regular care, including painting, sanding, sealing, and cleaning. Wood is also prone to bowing. Vinyl, on the other hand, does not need to be painted or sealed, although it still needs to be cleaned at least once a year. Vinyl is not the traditional material used for pergolas, but the fact that it is low maintenance makes it a popular choice.
Climbing vines and plants are a pleasing addition to a pergola. Mature vines can completely cover the pergola's upper trellis and provide shade. If the pergola is secured to the ground, the vines can be planted beside the support beams. For pergolas that are installed on a deck or patio, the vines can be planted in large pots and placed beside the supports. In either case, large pots with poles for training the vines can be placed next to the wall side of an attached pergola.
As an architectural feature, an attached pergola acts as a transitional space between the outdoors and indoors. Often a sitting area is arranged under a pergola to create an outdoor living space that is comfortable and shielded from direct sunlight. Since it is attached, the pergola acts as a shade to any windows on the side of the building. Attached pergolas can also be used to connect detached buildings, like a pool house or garage, to the main house.