Foundation Helical Piles
Repairing Bowed Foundations Using Helical
Piles
Helical piers are used for foundation repair projects as well as new construction projects in poor soils. Helical piles are screwed through many different layers of earth until it hits the bedrock. Think of these piles like large earth screws. They are made of steel and will be screwed, using either truck mounted or excavator with special rotary head, into the ground until they become stable.
The Purpose of Underpinning
When a foundation wall moves or cracks the wooden frame above (which may be bolted to it) will try to move with the moving foundation sections, and can get damaged. This can result in the upper structure having bowed and cracked walls and floors; racked doors and windows; and even structural failure (where members begin to crack).
Uses of Helical Piles
Uses for helical piles include foundations for houses, commercial buildings, light poles, pedestrian bridges, and sound walls to name a few. Helical piles also are used as underpinning elements for repair of failed foundations or to augment existing foundations for support of new loads. Helical piers can be driven into the soil horizontally or at an angle; it doesn’t just have to be used vertically. When used horizontally or at an angle, helical anchors are effective at reinforcing retaining walls and foundation walls. In new construction they are used in the place of “old fashioned” drilled concrete piers. The amount of torque required to install is directly correlated to their capacity.
Installation Process of Helical Piles
Once the pier has been installed, a steel bracket connected to the pier is secured against the foundation to stabilize it. In some cases, the foundation repair contractor may jack the foundation up to get it closer to its original position before securing the bracket.The total number of piers, and where they are placed, will also depend on the extent of failure, weight of the supported structure, condition of the foundation, and the type of pier you decide to use. Each of them has their benefits and situations where they shine. The greatest numbers of piers are usually required along the perimeter of the foundation due to weight and this is where failure generally occurs. If the interior area of the foundation is also sinking or shifting, piers may be necessary there too.
Pressed Concrete Piers Discussed
Pressed concrete piers are probably the cheapest of all pier types. That is why it is the most commonly used method of foundation repair. In some areas, they account for more foundation repairs than all other methods combined. They are also why the foundation repair industry has a “black eye” in the mind of the average homeowner.
How Micropiles Can Be Used
Like helical piles and push piers, micropiles can be installed in limited access areas with relatively small equipment. This maneuverability makes them ideally suited for foundation repair applications. Portable equipment has been developed to allow for access to basements and other low overhead applications where soils or access is limiting to other more conventional methods of foundation repair.
Other Anchoring Methods
Solid square shaft helical piles have been used successfully for decades in tension applications; i.e., as anchors, tie backs, and soil nails, and have proven to be a suitable and reliable support alternative for such projects. (Tie Backs are a helical anchor that transfers a lateral load from a failing wall to suitable load bearing soils. Used on new and existing walls for vertical support and slope stabilization) Not surprisingly, some manufacturers have then adapted the use of square shaft helical piles to include support of compression loads.
Different Perspectives
From an engineering /architecture standpoint, Helical Piles can be adapted to support many different types of structures with a number of problematic subsurface conditions. From a contractor perspective, they are easy to install and capacity can be verified to a high degree of certainty. From the public perspective, they are perhaps one of the most interesting, innovative, and environmentally friendly foundation solutions available today.
If you have a sinking basement wall or bowed basement walls, contact us to discuss if a foundation helical pile is necessary or which type of underpinning method will be best for you.
