By Murphy Bros. Project Mgr. Drew Johnston and Marketing Director Tom Myrick
Helical Pier foundations are a growing trend in building that could save you time and money.
Whether you are building a pyramid in Egypt or a deck off your second story patio door, a solid foundation is critical. And in most residential cases, that foundation has been made of concrete. However, in the past decade or so builders have been rediscovering a method that dates back more than 100 years. Although more commonly used in commercial construction, helical piers are becoming more and more utilized in residential building and remodeling.
Helical piers, also referred to as helical piles or screw piles, were developed to structurally support offshore foundations such as lighthouses in the 1800's and were modified over time for inland use. They are essentially large earth screws made of galvanized steel, can be a bit more expensive than traditional poured footings but with the logistics, hours and lag time that accompany traditional concrete footings, helical piers may be a solution for many jobs moving forward. When all is said and done, in some instances, they can actually reduce costs.
Helical piers are used primarily in areas with unstable or variable soil conditions. They are able to get below the topsoil and reach stable ground to provide a solid foundation.
The piers are installed with a skid loader or a walk-behind unit, depending on the project accessibility and size/depth of the piers, with a special attachment to torque the pier to depth.
As seen above, piers are installed at 5’ increments, with the first length being the spiral cutting blades. Each following length is attached to the shaft with through bolts. The pier is installed until a required torque is registered. The required torque is predetermined by the soil condition and the load requirements for the project. The torque reading and corresponding kip measurement is produced in a printout that is then sent to the city officials for footing inspection.
In the Twin Cities, most communities have homes built in areas with high water tables or expansive soils, and it is becoming more common for professionals in the industry to recommend helical piers over concrete.