Push Piers vs. Helical Piers
Push piers and helical piers are different types of mechanisms for supporting the structure of a building. A push pier functions as a giant nail – it’s pushed into the ground using a hydraulic ram and provides strength by compressing down on the solid ground underneath. A helical pier is a giant screw rotated into the ground and provides strength based on the torque and resistance from the soil around it. Each is used in a slightly different way, and each has a slightly different set of strengths.
This guide will cover the key information and help inform you about which one may be best for your home.
WHAT ARE THE DIFFERENCES IN BUILD SPECIFICATIONS?
The key difference between push piers and helical piers is that helical piers have helical plates attached to the central pipe. This means that they can be ‘screwed’ into the ground. The strength of helical piers comes from the torque of the insertion process. By contrast, push piers are ‘pushed’ into the ground. The strength of push piers comes from the ‘refusal’ – the point at which it meets solid bedrock. The greater the weight of the structure above it (i.e., the building), the stronger the ‘hold’ on the ground.
Aside from this key difference, there are smaller distinctions you can make between the two types of piers. Taking a standard 3.5-inch pier as a comparison, you can see that there are the following distinctions:
External sleeve wall
Yield strength minimum (i.e., the amount of stress it can hold without deformation)
Tensile strength minimum (i.e., the stress load it can carry per square inch)
Allowable system capacity (pounds per inch it can carry)
32.5 - 44 kips
Does the pier meet ICC codes for safe design in construction
These differences highlight the small but crucial implications in the different ways that the two types of piers are built. The nature of each gives them very clear strengths and weaknesses, particularly when it comes to strength. These differences shape the way that each is used in construction and the type of project in which both are used. The section below will discuss the different functions in more detail.
WHAT ARE THE DIFFERENCES IN FUNCTION?
As the above section shows, the way that the two piers are constructed has an effect on their function. The three key distinctions are outlined below:
Despite the fact that push piers rely on a building’s weight to stay in place, helical piers can actually carry a heavier weight. In addition, because of the way that they are twisted into the ground, their strength comes from the torque with the ground, and only secondarily are they connected to the building. By contrast, a push pier has no torque until the building is attached. In the case of shifting soil (or sand), a helical pier can bear a great deal more.
Although both options can be extremely enduring – particularly compared with other methods of raising up a footer, helical piers do have a clear advantage when it comes to how long they will last. Most push pier manufacturers offer only a 10-year warranty.
By contrast, helical piers are likely to last as long as the structure they are attached to. This obviously excludes any external influences, such as soil shifting or seismic activity. In both cases, the essential structure of the piers is sound (and your home is unlikely to begin sinking unless something dramatic happens!).
When it comes to engineering, most elements are stress tested. This means that they are able to endure far beyond what they are usually expected to experience. Piers are no exception. Because of the design of helical and push piers, the stress factors are very different. Push piers are totally reliant upon the weight of the structure to provide their strength. If the house shifts and the pressure releases on the piers, they offer no strength at all.
By contrast, helical piers are strong regardless of the weight or movement of the house. This gives them an edge when it comes to strength in the face of additional stress.
When are push piers preferable?
Push piers are more common in construction projects throughout the United States. As the above section has shown, however, push piers have a number of limitations that helical piers do not. In a lot of situations, however, push piers are a better choice.
As mentioned throughout, push piers are very much reliant on the weight of the home to provide strength. While this may seem limiting, it does, in fact, have some major advantages in some circumstances. Most obviously, that means in situations where a large or heavy building has experienced some sinking of its foundation. In these situations, the high compressive strength of a push pier will provide a great deal of stability. After all, there’s a reason why push piers are commonly used when dealing with skyscrapers.
In addition to very large buildings, buildings with a poured concrete footing and/or a concrete foundation wall tend to be well-suited to push piers. These types of buildings not only have a slightly higher weight but also have the structural ability to utilize push piers. The large slab making up the foundation is extremely easy for the brackets to latch on to and makes it relatively easy for contractors to insert the piers in a suitable location.
Push piers also work well when there is relatively little space in which to work. Because they are inserted in small stages, using extensions, and because they are inserted vertically down, you need only have a space of 3 feet by 3 feet, with roughly 6 feet of headroom, and you can install a push pier system. For buildings with crawl spaces, this is usually a workable option.
When are helical piers preferable?
Helical piers have a number of inherent structural advantages – such as being strong independent of the structure they are attached to. This means that for smaller buildings, helical piers are the only workable option. For example, if you have a single-story building, a push pier is likely to not provide the required anchorage, and a helical pier is the only option available. For example, any building with two stories or less is well-suited to helical piers rather than push piers.
As hinted above, for buildings without poured concrete flooring, a helical pier may be a preferable option. For most other foundation types, in fact, a helical pier will be the best way of either pre-empting any sinking or simply responding to any sinking or shifting that may have taken place. For that reason, helical piers are preferable in older buildings (particularly historic ones) that may have begun to subside due to movement of soil or other related factors.
In some cases, helical piers are actually added to new buildings as a preventative measure. The space required for helical piers is often less of an issue when it comes to new buildings, and the added strength is obviously a major benefit.
One further consideration is the type of soil. Helical piers were invented to anchor large ships to sand or sandy soil. The fact that helical piers were adept at doing so means that they are still a preferred option for buildings built on soil that is not solid enough to provide support on its own. Again, this is particularly applicable when it comes to older buildings, which may have sunk over time because of the lack of support from the soil underneath. In areas of the United States with sandy soil, a helical pier may be just the ticket.
WHAT ARE THE COST DIFFERENCES?
THE OVERALL COST
Obviously, there are a lot of factors involved in the cost of different types of piers. The most notable of these is the cost of living in your area.
However, as a ballpark figure, the cost per push pier is likely to be somewhere between $2,100 and $2,500.
The cost per helical pier is between $2,100 and $3,000. Generally, a helical pier is around $200 – $300 more expensive per pier than a push pier. This is because of the additional labor involved in installing it. A push pier can be installed by one contractor, whereas a helical pier usually needs two or three.
Both helical and push piers are extremely solid options for your home, and either one of them can do an excellent job of supporting the foundation and structure of your house. In fact, it’s fairly rare to have an open choice between the two – the circumstances usually dictate a clear preference for one over the other.