In almost every case, the building of a concrete, stone or brick footing is a prerequisite for the proper construction of an outdoor wooden deck. The deck needs a solid, unmovable support system that will withstand all weather as well as the change in seasons. By far the most common method of making footings is by pouring cement into a small form that eventually hardens and creates a pier for an upright post or support system. Does this Spark an idea?
Significance
The placement of the pier is the first and most-important step that one undertakes when building an outdoor wooden deck. The piers can be ready-made (usually pre-cast concrete) or constructed on site with a plywood form and poured concrete. Concrete reinforced with metal rods (usually called rebar) or steel mesh has become the most popular material used for this purpose. This method has the distinct advantage of being a poured material and thus the exact height of the footing is easily achieved.
Footings for decks usually come in the form of piers, so correct location and size are critical. To properly design a deck one may have to consult an engineering manual or an actual engineer.
Function
The footing must be a reliable support for the wooden frame that holds the deck floor. It needs to be below the frost line and have enough mass and reinforcement to support the load of a deck, plus all possible additional weight such as people or deck furnishings. It is also possible that your deck might contain a snow load during the winter months. For a deck that is an extension of the house frame it is vital that a footing perform all these tasks. Depth of the frost line usually varies between 2 and 4 feet. This exact depth can be found by inquiring with the local building code. Structural strength is a function of the size and depth of the footing. Basically the more mass (or volume) that a footing contains the stronger the footing will be and the larger the load it can carry.
Features
A concrete footing almost always contains metal reinforcement. This can be in the form of solid rebar or steel mesh. The metal is placed in the form before the wet concrete mix is added, and one must be careful that the metal is spread evenly throughout the wet mixture. In some forms it is possible to install the reinforcement immediately after the cement has been poured or even during the pouring process. The concrete should always be a mixture of gravel, sand and cement. Purchasing bags of ready mix or ordering a load from a cement-mixing company will ensure that you always have the right mixture.
Considerations
A metal anchor bolt is almost always set in place at the top of the footing right after the concrete is added. These bolts consist of a piece of threaded rod that is inserted into the wet concrete so that at least half of the bolt is buried beneath the surface. When construction of the actual deck begins, this piece of metal will take a wooden plate. Then a washer and nut are added and tightened to hold the plate in place. The wooden frame is built on top of the wooden plate and then attached in some sort of way to the plate as a safety precaution.
Expert Insight
A free-standing deck that is planned for your backyard or garden may not need the larger footings that a deck attached to a building requires. This is especially true if the platform is built on level ground and does not have a large height between the ground and the platform. Depending where you live the deck may not be subject to any building codes. Smaller footings, especially the pre-made variety, may work just fine in these situations. Again, do your homework and lay out the piers so that they can support the size deck you plan to build.
Tags: almost always, concrete added, deck that, frost line, outdoor wooden
