Since 2002 Granite Foundation Repair has been installing Helical Piers for residential home foundation repair. How are Helical Piers installed? What makes Helical Piers so good? These questions are good to know when you are in need of a foundation repair or trying to determine which method to use.
This article is written for the layman, and will not go into the mathematical formulas which form the basis for Helical Pier installation guidelines. Helical Piers are also known as Helical Pilings and Screw Pilings.
Helical Piers are a proven technology. They were developed over 150 years ago in England and used to stabilize lighthouses. A later variant was an application of the Helical Pier referred to as the Anchor Piling. Anchor pilings are constructed with a square tube and round plate. An anchor piling relies upon soil overburden to prevent pulling the piling from the soil. Typical uses for anchor pilings include tie downs for tents, retainer walls, mobile home tie downs, basement wall tie backs and telephone poles. Anchor pilings with square rods should not be used by foundation support.
Helical Pier Construction
A Helical Pier consists of one or more round plates welded to a square or round shaft. The plates are cut and twisted into a helix shape, resembling a single screw thread. Hence, the alternate name for a Helical Pier is a “Screw Pile”. The name for the plate is a “ Helix”. Additional shafts are added to obtain depth. When multiple Helix’s (plates) are used, they are typically spaced 3 times their diameter along the piling shaft. Two 10 inch plates will be spaced about 30 inches apart. The first plate is installed near the leading edge of the shaft. The leading edge of the shaft is referred to as a pile toe, and is slanted to auger into the ground. When used for foundation support, the shaft is normally a round shape, resembling a pipe. Square shafts are great for anchors but offer poor support for foundations. Square shafts do not have the ability to resist bending under load. Round shafts can resist bending under load.