How to Plan and Design a Deck Overhead Structure

By admin0 | September 16, 2007

A deck overhead structure such as an arbor or pergola can provide a measure of shade, be decorative, offer relief from the wide open sky, provide rain protection as well as a sense of design balance. In developing a plan and design for such a deck amenity, it is important to consider its location, size, dimensions, overall appearance, orientation and roof details.

For a deck overhead structure that is attached to the house the height of the home’s roof overhang determines some of the design options. In cases where the overhang is a minimum 9 feet above the deck surface, the roof can be tucked under the eave. Otherwise, attach the overhead to the house roof itself or construct a freestanding structure that clears the roof eave.

For minimum shade purposes, plan a structure without any canopy above the rafters or one consisting of very few slats. In cases where additional shade is desired, place slats no farther apart than their depth. For example if the slats are 2×4s, space them 3.5 to 4 inches apart. Slats oriented east to west provide shade except during the early morning and later afternoon hours. Slats oriented north to south will admit sun at noon and provide shade late in the afternoon.

In oder to obtain maximum shade, a solid roof can be installed. A possible compromise between an open structure and a sold roof would entail planting vines such as clematis or wisteria that fill out the canopy during the summer months but drop their leaves in the fall.

Plan the overhead to be large enough to accomodate seating under it and high enough to provide approximately 8 feet of clearance. Balance the overhead with other elements that are vertical in the yard landscape such as trees, tall shrubs or the house itself in order to keep it from overwhelming the deck. In planning the individual components of an outdoor structure such as posts and beams, it is wise to consider the overall scale. A 6×12 beam to span between posts might be a more appropriate size visually than a 4×8 beam.

Any overhead structure will most certainly affect any views from the deck. It blocks specific views, especially of the sky. However, it can also frame views of the horizon for a very pleasing effect.

It is certainly possible to build a deck overhead structure that appears light and airy or massive and dominant, refined and elegant or rustic and comfortable. In situations where the home and landscape reflect a formal style, align the overhead with a definite axis, keep the overall design symmetrical and select elegant details. If the home has traditional architecture, an overhead with a Victorian motif with gingerbread or intricate scrollwork or lattice will work, especially when finished with white or richly colored paint. Each element of the overhead structure has the capacity to contribute to the overall look.

A deck overhead structure must be designed and constructed to withstand the same loads and stresses as a conventional roof. Footings must be able to adequately support the weight of the entire structure plus any snow loads. The structure must be attached securely to the footings. Individual beams, rafters and slat and lattice members must be large enough and have the strength for the spans involved. Finally, the overhead structure needs to be rigid enough to withstand any lateral forces. To do this, strong connections possibly including knee braces or diagonal bracing must be utilized.

Any deck overhead must be able to resist deterioration caused by constant exposure to the sun, rain, snow and other elements. All connections must be corrosion resistant. Wood components should be a minimum of 8 inches above ground unless they have been treated with a preservative specifically designed for contact with the ground. Overhead structure wood members must also be securely fastened to counteract warping and cracking. A wise decision would be to apply a finish coat of sealer to the deck overhead structure to protect this structural investment.

Taking the time to carefully plan and design an deck overhead structure will guarantee that this deck amenity will contribute positively to the enjoyment by family members and guests of the entire outdoor living space.

Topics: Deck overhead structure |