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Helical Piers for Decks: Pros, Cons, & FAQs
When Rise's CEO and Founder, Matt Daigle, was planning for his new deck, he wanted to make sure it would be low maintenance and extremely durable. Who can blame him? Decks represent a significant upfront investment. If we don't pay attention, it's easy to choose materials or make choices that will mean ongoing maintenance and frequent repairs.
After Matt chose thermally modified wood as his decking material (watch that research unfold in this video), it was time to select a foundation option.
Anyone who researches deck foundations will quickly face the ultimate question: helical piers or concrete piers? It's evident by the title of this article what Matt chose. So, to save you the Googling, we'll lay out the results of his research here. Keep reading, and we'll take a look at the pros, cons, and frequently asked questions about helical piers (also known as screw piles) for decks.
Table of Contents
What Are Screw Piles?
Screw piles, or helical piers, are a type of foundation system. This method of supporting a structure has been around since the 1800s - which hints at their long lifespan. They're essentially giant galvanized steel shafts with screw-like flanges. To install screw piles, they are twisted into the ground to a depth that the torque required to turn them indicates proper soil bearing capacity.
Usually, installation extends to just below the frost line. They can sometimes even extend to hundreds of feet down, depending on soil conditions.
These piers can be driven into most types of ground. However, if solid bedrock is encountered, it requires some pre-drilling, which will add to your cost. Stony soils are okay, but sometimes you might hit a large enough rock to have to start the process all over again and reposition the screw.
Advantages of Screw Piles
Screw piles are quick to install — it's kind of like an instant foundation. They work in a variety of soil conditions, and the installation is pretty cost-effective. Screw piles have relatively low embodied energy and are relatively non-intrusive in the surrounding environment.
Disadvantages of Screw Piles
While they're easy to install, screw piles are not a DIY job. You need specialized machinery to install them.
How Much Do Screw Piles Cost?
On average, screw piles (helical pier) cost $250 per standard screw pile That price includes the full installation, brackets, and a helpful little engineering report at the end. This professional installation gives you the peace of mind, knowing that the piers are appropriately sized, correctly torqued, and will stay in the ground without shifting.
What's the Difference Between Screw Piles and Concrete Piers?
Now some of you may say that's a hefty price to pay for a single pier, and you might be right. But consider concrete piers for comparison. These are another common pier wherein a hole is dug, and concrete poured. Concrete piers are likely the most commonly used alternative for backyards and other pier applications.
How Do Screw Piles Impact the Environment?
Most of the embodied energy that goes into making helical piers stems from the harvesting and manufacturing process, and a bit in transportation. They're typically made from steel and coated with zinc and require sources of high heat. One advantage is that waste from this manufacturing process is quite low and mostly from offcuts. That said, the overall embodied energy for helical piers is relatively small.
How Long Do Screw Piles Last?
Durability and longevity are also critical to the helical pier's low impact. These products typically last a very long time. Their durability is, of course, dependent on the quality of the pier and the soil in which it is placed.
How Might Screw Piles Impact Your Health?
Steel piers have very little to no impact on their surroundings from a health perspective. Typically we'd look at any potential off-gassing from the material or any possible soil contamination in their vicinity. Soil health is also an excellent reason to pick a galvanized finish over a painted one.
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