What is a helical pier?
Helical piers are not new to the construction industry. In fact, they were being used as far back as the the early 1800’s for lighthouse foundations. Helical piers are also known as helical piles, helical anchors, screw piles, and screw anchors. Helical piers are basically large metal screws that are driven into the ground. They are typically used as footings for structures when traditional masonry footings are not a practical or economical solution.
How does a helical pier work?
Engineers have determined that the amount of force a pier can resist is proportional to the amount of torque that’s required to spin them into the ground. So, the beauty of this foundation system is that you’re guaranteed to end up with a solid footing every time. That’s because the installer will monitor a torque meter that’s attached to the drive head and will keep on drilling down until the required amount of torque is met.
Helical piers for poor soil conditions
Combating poor soil condition is where helical piers have traditionally been used. If you have to build a lighthouse in a swamp, digging down fifty feet to hit solid soil is not a great option. But driving down a bunch of piers is relatively easy.
Helical piers to strengthen existing footings
Beefing up existing footings has become another common example where helical piers are being used. If a contractor is hired to add a second story addition to a home, it’s probable that the existing footings were not engineered to handle the additional weight. Instead of excavating around the entire foundation to increase its size, the contractor could drive helical piers into the soil alongside the existing foundation and fasten the two together with straps and brackets. Of course, an engineer would have to come up with the exact size and spacing, but that would also be the case if concrete footings were to be installed.
Helical piers for deck footings
Helical piers are also fast becoming the go-to footing solution for decks, porches and additions. No matter how hard you try, the use of the heavy equipment needed to build concrete footings is going to destroy a finished yard and likely frustrate the homeowner. Helical piers don’t require any excavation, and there’s no need for concrete trucks. There are some walk-behind machines that are so small and maneuverable that they can even drive down piers inside a home.
Best machine to install a helical pier
Some commercial projects will require a large excavator, but most companies working on residential projects are using mini track excavators because they have a lighter footprint and can maneuver much better in tight spaces. Skid steers can be set up to drive piers as well, but they are harder on the terrain and require more space, and nothing can beat the dexterity of a mini excavators fitted with a gimbal style drive head that can spin 360 degrees.
Here are some other situations where the use of helical piers is ideal:
- Limited access areas
- Remote areas
- Water locations
- Footings in wetlands
- Railings supports
- Temporary footings
The benefits of helical piers vs. standard masonry footings:
- High capacity capabilities
- Vertical or horizontal load stabilization
- Quick and efficient installation
- Can reach tight spaces
- Less mess / No excavating required
- No need to bell a hole for a concrete pier footing
- No hauling out fill
- Accurate installations
- Unlimited depth
- Can be installed in the winter
- Can’t freeze, crack or heave
- Can’t fill up with water
- Can be removed
- Fast installations
- No dry times/ ready for instant use
- One-time visual inspections
- Brackets on a threaded rod can be set and fine-tuned to a desired height
- Custom brackets can be made
- Can steer around or power through most rocks that are basketball size or smaller
How much do helical piers cost?
Helical piers are more expensive and may not be the footing solution for every project. But more and more contractors have figured out that there is no other footing that makes more sense when dealing with finished landscaping, tight spaces or poor soil conditions. In the Twin Cities area the average cost of an individual pier footing spec’d for a deck, porch or small addition range from $200-$250 each. Before ordering, check with your helical pier contractor to make sure they have completed the proper training and have received the certification that is usually required for installing these piers.