When you see a home along a coastline or high in the hills and it looks like it’s built on stilts, you’re looking at a home that has a pier foundation. Piers are also used for less dramatic purposes and for building additions closer to ground level. Building on piers provides advantages such as access to plumbing and electrical work. Depending on the climate, the addition to the home may even use less energy because it won’t be sitting on a cold concrete slab.
Post and Pier
A post and pier foundation is made with spot footings of gravel or concrete under wood posts or concrete piers. Support beams are laid on top of the pier to form the frame for the building. The posts are typically spaced 8 to 12 feet apart and always according to building code requirements. Post and piers are suitable for building an addition such as a guest bedroom or a deck. However, it can only be used in locations not prone to hurricanes or earthquakes because the structure will give way to strong winds or violent shifts in the soil. The ground must be very stable when using a post and pier foundation structure.
Concrete Tube Pier
Concrete tube piers are used in cold climates and locations with heavy clay soil. Tube piers provide an addition with a good anchor against strong winds. The pier is made of concrete poured into a grade-B cardboard form to create a tubular shape. The concrete tubular pier is reinforced with heavy-gauge rebar. The tube-shaped piers rest on a circular concrete footing installed below the frost line, which is soil that is deep enough that its temperature never falls below 32 degrees Fahrenheit. Another advantage to using tube piers for additions is that you can make the tubes different heights. Tube piers are often used for building an addition such as enclosed patio or family room for a home that’s on a hillside or slope.
Concrete blocks are also used to build additions on piers. Called block piers, this type of construction uses common 8-by-8 or 12-by-12 concrete blocks. Block piers are used when building an addition on a level surface, rather than on a slope. Block piers can be used for simple additions such as a deck that’s close to ground level or an outdoor gazebo, and they are commonly used by homeowners in the southern states.
Homeowners sometimes run into foundation problems when they want to build an addition. In these situations, pressed piling piers can provide a solution. Pressed pilings use friction to repair the sections of the home that have structural problems and are used to create the pier for the new addition. They are made of wood or steel and are driven into the ground as far as 8 or 10 feet, or as deep as necessary for the piers to restore the stability of the home and provide stable footing for the new addition. Decks, additional bedrooms, and above-ground garages are examples of home additions in which pressed pilings are used to support the foundation. Pressed pilings are typically used in coastal areas and in locations that require building above the base flood elevation to comply with insurance requirements.