Decks have played a role in history since the earliest times. They have been used for storage, dining, foraging, and socializing. In early America they were much larger than they are today and were constructed of wood. In fact, they were constructed in colonies such as Plymouth and Cape Cod. Decks were used as summerhouses, places of relaxation, for drinking, roasting marshmallows, playing games like chess or billiards, building watercraft, and a number of other outdoor activities.
In architecture, a deck is basically a flat open surface capable of holding weight, usually attached to the building, and often raised from the ground. The word deck is actually a combination of two words: decking and rail. Railings are placed on the outside edge of a deck, typically six to twelve feet above the ground. They are usually made of wood and have cross boards or a web of vines that allow for stability. Screws or nails are used for attaching the rails to the building.
A basic deck is usually constructed of wood products including ledger boards, batts, and blocks. The most common materials used in the construction of decks are wood and wide planking; these materials are used for constructing slabs or piles that support the decking. The most significant part of the deck is the under layer of hard-packed soil that is placed between the slabs of wood and the soil. This layer is called the hidden fastener and contains the minimum height required by the local building code. One of the most popular features of decks is their ability to be built with raised paneling which is an arrangement of panels that are attached to the edge of the deck and extends from end to end forming a stairway like pattern.
The boards that make up the underpayment of a deck are placed over a layer of gravel or crushed stone. This layer also contains decorative material such as brick or stone. Asphalt or tar interlocking is commonly used on the surface of the boards and its grouting process makes it very durable and slip resistant. The engineered lumber that is used for decks is pre-fabricated consisting of material that resembles solid wood except for the fiber-board layers that give the product the appearance of wood. These products are constructed using standard lumber milling methods.
In addition to the joists, floor joists, edge joists, sub-slab edges, and end edge joists, there are other important parts of a typical deck. Decking head rail systems, post caps, and capstans are all part of the deck package. Deck construction generally consists of four materials; iron, wood, composite lumber, and deck blocks. Most decks constructed today use either heave or screw systems with a heave system being the more popular choice.
A screw system provides the greatest strength and durability. Deck systems are built with one or two post caps that provide attachment to the end of the deck. The caps help provide maximum strength as the system is attached to the posts and to each cap in turn provides added support for the entire deck. There are differences between the different deck types which include a concentrated load of lumber and deck blocks or a combination of both.
Heave systems combine boards of different heaves and screw them together creating a board with less density. Heave boards are usually shorter than ordinary engineered lumber. These shorter flexible boards are used for decks that have a lower concentration of heavier structural materials. Generally, heave decking boards are not used in applications where a higher concentration of heavier materials is needed. In addition, because heave decking boards are shorter, they have less dimensional stability than do traditional engineered lumber panels.
One of the most versatile and frequently used decking materials are composite decking boards. Composite decking boards can be used for decks that have varying levels of reliance on gravity or weight distribution. For instance, the heavier the load, the greater the amount of decking material needed to achieve the desired level of stability. On the other hand, lightweight decks rely less on decking stability and more on dimensional stability due to the presence of shorter core sizes and long length framing members. The presence of a rim joist is important in heavier applications where extra support is needed but dimensional stability and strength are not an issue.