Foundations for Modular Buildings: Understanding Your Options

ground screws for modular building

Foundation options for modular buildings

Modular buildings arrive on site as complete units, precision-engineered and virtually ready to use. 

However, their success and longevity rely heavily on the foundations they’re placed on. 

Without the right support, modules can swiftly develop serious problems, from leaks to structural issues that risk ongoing problems with windows, doors, and other fittings. 

Every support point needs to be perfectly level. If not, the sections simply won’t align properly.

In this guide, we’ll take a closer look at the different types of foundations suitable for modular buildings, from traditional concrete bases to modern ground screws. 

We’ll also share practical installation advice and real-world examples to help you install modular buildings perfectly – and avoid unnecessary problems down the line.

Why Foundations Can Make or Break Your Modular Building

Every great building project starts with laying solid foundations, and modular construction is no different. 

Even small errors in the foundation can lead to big problems for your build, including:

  • Gaps between sections, letting in drafts, water, or pests
  • Misaligned doors and windows that stick or fail to close properly
  • Floors developing uneven movement or squeaking underfoot
  • Strain on internal fixtures like partitions and cabinetry
  • Visible gaps in external cladding, compromising the finish

Whether you’re setting up a small garden office or a large multi-unit complex, laying accurate, durable foundations is critical to ensuring your modular building functions as intended and stands the test of time. 

So what are your foundation options?

Understanding Modular Building Foundation Options

Modular buildings need solid, longlasting foundations, but choosing between the available systems can be complex.

Let’s examine how each option works in practice, along with their strengths and limitations.

Basic Concrete Blocks and Pad Foundations

The most straightforward foundation uses pre-cast concrete blocks or poured concrete pads. Installers place these at regular intervals around the building’s footprint, typically at corner points and along main beams.

While simple in theory, these foundations bring several challenges:

  • Achieving consistent levels across multiple blocks
  • Preventing blocks from sinking in soft ground
  • Managing water run-off and drainage
  • Dealing with ground movement over time
  • Limited adjustment once installed

Many temporary buildings start life on concrete blocks because they’re quick to place. But this apparent simplicity often leads to problems with doors sticking and floors becoming uneven as blocks settle at different rates.

concrete base
Concrete bases are a go-to for heavy buildings but don’t necessarily suit modular buildings.

Concrete Ring Beam Foundations

Ring beam foundations create a continuous concrete support around the building’s perimeter. This involves:

  • Excavating a continuous trench
  • Adding steel reinforcement
  • Creating shuttering
  • Pouring concrete accurately
  • Allowing several weeks for curing

A well-built ring beam provides excellent stability and load spreading. 

However, getting levels perfect during the concrete pour requires considerable skill. The process also involves significant groundwork, multiple contractor visits, and often weather delays.

Adjustable Jack Pad Systems

Jack pad systems combine concrete pads with adjustable steel supports. They offer some flexibility for leveling and can handle moderate ground slopes. 

Commonly used under temporary classrooms and site offices, they provide a middle ground between basic blocks and full foundations.

However, they still need:

  • Careful ground preparation
  • Regular level checking
  • Maintenance of adjustment mechanisms
  • Protection from water damage
  • Periodic readjustment

Steel Base Plates

Steel plates spread loads across larger areas, making them useful on softer ground. 

They work particularly well for temporary installations where ground preparation is limited. Modern versions often include integral leveling systems.

Limitations include:

  • Need for flat ground preparation
  • Potential rust issues
  • Limited height adjustment
  • Reduced stability in wet conditions
  • Regular maintenance requirements

Ground Screw Systems

Ground screws offer an alternative solution and have become hugely popular for modular construction. 

Each screw is secured deep into the ground, providing a precise mounting point that can be adjusted for perfect levelling. 

The typical ground screw system includes:

  • Engineered steel ground screws
  • Adjustable mounting brackets
  • Connection points for modular frames
  • Built-in leveling capability

The key advantages here are speed and precision. Installation often takes just hours, and the adjustable brackets mean you can achieve perfectly level foundations even on challenging sites. 

modular building
Modular buildings come in all manner of shapes and sizes. Thus, foundation options also vary widely.

Ground Screws for Modular Buildings Explained

Ground screws offer rapid installation and robust yet precise structural support – exactly what modern modular buildings demand. 

Here’s everything you need to know about what they are and how they work:

What Does a Ground Screw Look Like?

Each ground screw consists of a long steel shaft with helical (spiral) plates welded around them – resembling a giant screw. These plates allow the screw to be driven deep into the ground, anchoring it securely in place.

They come in various lengths and diameters to suit different soil conditions and structural requirements. 

How Do Ground Screws Work?

As the ground screw is rotated into place using a mechanical driver, the helical plates cut into the ground while compacting the displaced soil. The process creates a dense, stable foundation point that resists both downward pressure and lateral forces.

Each screw can be installed to a specific depth, ensuring consistent performance even in uneven or sloping terrain. 

Once secured, the top of the screw connects to the modular building’s frame via mounting brackets. Brackets allow precise alignment adjustments to achieve a perfectly level foundation.

ground screw modular building
Modular building mounted on ground screws.

Why Are Ground Screws Ideal for Modular Buildings?

Ground screws are a reliable and practical foundation solution for modular construction, offering consistent support and versatility. Their key advantages include:

  • Targeted load support: Screws are installed at precise locations to handle specific weight distributions and load requirements.
  • Rapid installation: The system is quick to install and ready for use immediately, with no delays caused by curing or heavy excavation.
  • Minimal disruption: Installation is clean and efficient, with no need for large-scale digging or extensive site preparation.
  • Long-term stability: Soil compression during installation prevents settling over time, maintaining structural integrity.
  • Adaptability: Suitable for various soil types and easily adjustable for terrain challenges.
modular building foundations
Ground screws are quick to install and robust; making them a superb alternative to traditional modular building foundations.

Where Ground Screws Work Best: Real Examples

Ground screws are highly effective for modular buildings, mostly thanks to their adaptability and ease of installation. 

They’ve become a go-to solution for sites where traditional foundations are disruptive, impractical, or forbidden by local authorities, but can offer benefits for any modular construction project. 

Let’s take a look at some real-world examples where ground screws deliver exceptional results:

School Buildings and Classrooms

Modular school buildings have become a practical choice for many schools, especially in light of the RAAC concrete crisis, which also affected some hospitals.  

Installing new classrooms or facilities on a busy school site isn’t easy – there’s limited space, strict deadlines tied to term dates, and the school day can’t just stop for construction!

That’s where ground screws come in, so why do they work so well for schools?

  • They can be installed quickly and quietly, so the school can carry on as normal.
  • There’s no need for noisy digging or constant traffic from heavy machinery.
  • The process is clean – no messy concrete mixing or piles of waste to deal with.
  • Projects can be completed during holidays or other short windows, with minimal disruption.

Another key advantage is flexibility. Schools often grow or change over time, and modular classrooms need to keep up.

Unlike concrete, with ground screws, buildings can be moved, expanded, or even removed without causing damage to the site. 

Commercial and Retail Units

Modular commercial buildings, whether they’re offices, retail spaces, or pop-up shops, need to be built quickly and with minimal fuss. Deadlines are often tight, and many projects are on active sites where disruption must be minimal.

With long installation times and site preparation requirements, traditional concrete foundations can cause delays and complications that ground screws solve. Here’s why they’re a superb choice:

  • Ground screws can be installed quickly, helping projects stay on schedule.
  • There’s no noisy digging or heavy machinery, which means less disruption on-site.
  • Installation is clean – no piles of waste or messy concrete mixing.
  • They’re suitable for both temporary structures and permanent buildings.
  • If plans change, they can be removed or reused without leaving a mark.

Again, flexibility is a key advantage here. Modular commercial spaces are often changed or converted, whether it’s adding more units, relocating to a new site, or dismantling temporary structures. 

Ground screws simplify these processes, essentially acting as a modular foundation counterpart to the buildings themselves. 

Expert Tips for Installing Ground Screws

Installing ground screws is relatively straightforward, but getting it right requires attention to detail at every stage. Since modular construction projects are quite complex and vary widely depending on the buildings in question, the site, ground, etc, professional installation is highly recommended. 

Our domestic and commercial installation teams handle modular building projects of all sizes, from single units to large commercial developments. 

Before any work starts, we conduct a thorough site survey to check:

  • Ground conditions and soil types
  • Underground services and obstacles
  • Access requirements for equipment
  • Final height and level requirements
  • Building connection specifications

On installation day, our team marks out each screw position precisely. Using specialised equipment, we drive each ground screw to the exact depth needed, then fit and level the mounting brackets. This creates perfect connection points ready to receive your modular building.

When it comes to making those vital final adjustments, our installers ensure each screw lines up with your building’s connection points, checking levels repeatedly throughout the installation. 

We’ll also verify the load-bearing capacity of each screw, especially important for larger modular buildings or challenging ground conditions.

ground screw install
Ground Screw Centre provides professional ground screw installation services for modular buildings.

Creating Modular Building Foundations With GSC

Ground screws have changed how we think about foundations for modular buildings, offering speed and precision that traditional methods struggle to match.

GSC brings 15 years of ground screw expertise to modular construction. Our nationwide teams ensure perfect foundations for your building, with every screw installed to exact specifications. 

We handle projects of all sizes, from garden rooms through to major commercial developments, providing the same attention to detail at every stage. Full load testing and site assessments ensure your foundations perform exactly as needed.

Ready to start your project? Explore our complete range of ground screws and brackets, or contact the GSC team to discuss your requirements.