Concrete piers are, by far, the most common method used in foundation repair due to their ease of installation, cost effectiveness, and general reliability.
Often referred to as “pressed concrete piers” in technical environments, the name is a perfect description of the product and process. Pressed concrete piers are installed by digging a 2’x2’ hole under the edge of the foundation and using a hydraulic press to push the 6”x12” cylinder into the ground. The cylinders are pushed to an average of 45,000 lbs pounds of force, at this point the piers are capped off and “shimmed” to an exact height using ¼” steel plates. In soils that are prone to shifting, side-to-side movement rather than up and down movement, a steel cable can be threaded through the cylinders to lock them in place.
One of the oldest methods of foundation repair, also referred to as drilled concrete piers, is still the preferred method of some engineers. This system is more invasive than the pressed pier systems because an auger is needed to drill an 8”-12” diameter hole 10’-15’ feet deep. Depending on the size and depth, this could be a hand held device or mounted on a bobcat or similar vehicle. Once the hole is dug, rebar is placed inside and filled with 3,500 psi concrete mixture. The hole must be left uncovered for 7-10 days for the concrete to sufficiently cure before the house can be lifted.
Because the drilled pier does not rely on the weight of the home to install it, the drilled pier is the most versatile pier, being used on both slab foundations, pier & beam foundations, and home additions.
Whereas concrete piers are the most common type of foundation repair, steel piers are certainly the most dependable method. While there are multiple variations to the steel piering system, Perma-Pier utilizes the double-walled steel pier. A double walled steel pier consists of 2 separate pipes, a 2 3/8” and 2 7/8”. Both pipes are ¼” thick, and cut into 1’ sections. The sections are then sleeved together to create a pipe section 1’ long and ½” thick. The very bottom piece of a steel pier is only 6” long and fitted with a friction reduction pad to ensure a smooth installation process. When these sections are pressed into the ground one after another, they overlap at 6” intervals forming a single continuous and immobile pier.
Once installed, the hollow steel piers are filled with cement-like grout to ensure against upheaval and rust. Steel piers can be locked with steel cable, same as concrete piers. Once this is completed, steel piers are capped and shimmed exactly like concrete piers. Steel piers have a success rate of over 99.9%.