If you’re looking for advice on the internet about alternatives to concrete foundations, especially with regards to home offices, garden rooms, home gyms and man caves, you’ll no doubt have come across the terms ‘ground screw’ and ‘screw pile’. 

The terms are often used interchangeably. In some cases, you may even see a single product discussed or advertised using both terms. But it’s really important to understand that ground screws and screw piles are different products. They work in different ways, have different capacities and perform differently. So, when selecting a product for your foundations, it’s integral that you know which you are dealing with so you make an informed decision.

The Difference Between DIY Ground Screws and Screw Piles

What are ground screws and screw piles?

Both screw piles and ground screws have similar appearances in that they look like large metal screws that are rotated into the ground in order to provide foundational support for a structure. They both often have a bracket or plate which can be attached to wooden beams, steel or concrete.

But they have different build qualities, require differing installation styles, and behave differently in situ. So, what are the key differences?

What is the difference between a ground screw and screw pile?

The two products take loads differently

Ground screws and screw piles carry their loads in different ways. Ground screws transmit their load to the surrounding area through friction between the surface of the screw and soil. Screw piles primarily carry the load on their helical endplate.

Screw piles can take more load

Screw piles and ground screws, with regard to garden structures, often perform a very similar job. But screw piles can take higher loads due to their end bearing plate. This means that you typically need much fewer screw piles to safely complete a job. Every project is different, but as a rough guide, nine helical piles would do the same job as around 20 ground screws (This number would typically cover a small to medium-sized garden room). You should remember this point when costing a project, because screw piles may often be more expensive “per unit” however if you use far less of them they can still end up being a cheaper option.

Screw piles typically don’t require pilot holes

One of the primary benefits of screw piles is that they can be installed manually, without the need for any groundworks. Pilot holes are not usually required. And in many instances, it is entirely feasible for screw piles to be installed by hand by the DIY-savvy. This is typically not the case for ground screws. Ground screws often need a pilot hole for installation, which adds another process in installation. And this is usually where providers make their money. While ground screws are often available more cheaply than screw piles, you will usually need to pay professionals to perform the installation.  

Screw piles are less susceptible to heave

Heave – the upward movement of a foundation caused by fluctuations in the moisture levels of the surrounding earth – is known to occur in all foundation types. But it is far less common in screw piles than it is when ground screws are used.

Heave associated with frost, moisture and root activity typically occurs in the UK at a depth of 1-1.5 metres below ground level. Ground screws take their load through friction which is spread across the thread that runs up the screw. This thread typically covers 50-100% of the screw. Any instance where heave occurs and is in contact with the load-bearing thread can leave the ground screw susceptible to heave.

In contrast, a screw pile carries its load on an end bearing plate which 99% of the time is installed below any heave activity. Areas that might be affected have contact with the screw piles tube which provides no friction. So movement can happen but the end anchoring plate is left unaffected.

Are ground screws or screw piles the best option for your project?

Every project has its own unique set of requirements. But screw piles are typically the more secure and durable option. With low levels of disturbance, easy installation – even in areas where there may be obstacles, such as tree roots – minimal vibration, and strong load-bearing capabilities, screw piles can offer strength, versatility, and ease. And if you change your mind about your build at a later date, screw piles can be removed with little disturbance. While ground screws share some of these qualities, they typically do not have anywhere near the same load-bearing capacity as screw piles, so you will always need more. You will also usually require professional help to manage installation, and for later removal.

Screw piles and ground screws have surface similarities. And it’s easy to see why the two terms are often confused. But before you begin your next building project, make sure that you understand the differences. And find the best product for your needs.

If you need help finding the best screw piles for your next project, get in touch with UK Helix

Disclaimer –Information in this blog does not in any way constitute building advice or guidance for private or commercial building projects.

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