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Ground Screws for Annexes

Create more functional living space in your home with a garden annex. We offer robust, efficient, and compliant ground screw foundations and joist bases for annexes of all styles, shapes, and sizes. Whether you're a private homeowner or a company building annexes for clients, we provide load testing for building control approval and a fast, environmentally friendly alternative to concrete.

The benefits of ground screws for annexes

  • Rapid Installation

    Fast and effective installation which requires no digging or concrete, creating an immediate foundation for your structure.

  • Tested and Quantifiable

    Our ground screws can be compression load tested, and our helical screw piles are installed with calibrated torque monitoring. Both produce certified data for building control approval.

  • Designed to last

    Our ground screws are fully galvanised to BS EN 1461:2009. Our helical screw piles are manufactured to EN 1090-1, ISO 3834, and EN ISO 1461. All products are CE-approved.

  • Immediately load bearing

    Both ground screws and helical screw piles are immediately load-bearing – so as soon as they are installed, you can start building.

  • Ideal for permanent structures

    Engineered for habitable, building-control-regulated annexes, with a 20-year guarantee on ground screws and a design life of up to 100 years on helical screw piles.

  • Environmentally friendly

    Reduced CO2 compared to pouring concrete. Helps protect habitats and prevent damage to tree root systems.

  • Lightweight & Compact

    Ground screws eliminate access issues – screws, brackets, and tools can all be carried by hand. Helical screw piles are installed using compact tracked machines, suitable for tight residential gardens.

  • Reduced Disruption

    A screw foundation system minimises disruption to your property and your neighbours, involving less noise, debris, and disturbance than traditional foundation construction.

Make more space for living

A garden annex is a popular extension to increase the value of your home. These self-contained units can be used as a guest suite, home office or workshop. The granny annex is also a popular choice for multi-generational living.

Whatever your plans for your extra living space, high quality Ground Screws can help make them a reality. You can manage the construction of your garden annex from start to finish with the help of our Ground Screws for annexes. No more digging up your lawn or clearing trees to gain access. Ground Screws can be carried to the site and installed by hand, meaning access is rarely an issue.

Kinder to the environment

The outdated method for building a garden annex would include digging deep excavations for the foundations and then filling them with concrete. Concrete can pollute nearby waterways and digging for the foundations can disrupt local wildlife and will create mess.

If you want to protect and preserve your garden while building your annex, Ground Screws can help you to achieve this goal. Ground Screws for annexes produce around 60% less CO2 than concrete, making it a greener and kinder choice that will limit damage to the surrounding areas.

Why choose Ground Screws for your Annexe?

Ground screws present numerous advantages for annexes. Their rapid installation – often within hours – means quicker occupancy. They minimise site disturbance due to requiring no excavation compared to conventional foundations, which is particularly advantageous in residential areas where neighbourly consideration is paramount.

Their versatility enables installation across various soil types. Ground screws are adjustable to ensure precise levelling, which allows you to accommodate undulating ground or elevation changes. From an environmental perspective, they are highly favourable, generating far less carbon emissions during installation and offering reuse potential. Savings arise from reduced labour, no digging, no soil removal, and a reduced working schedule. Their structural stability assures enduring support for annexes of diverse designs and sizes, ensuring their long-term integrity.

Load Testing & Building Control Approval

Due to planning permission requirements, structures that are used for living or short-term stays require building control approval and planning permission. As part of our service, we provide a site-specific compression load test on our ground screws which proves the load capacity in the site soil conditions, aligned with the load requirements set by a structural engineer.

For annexe builders and developers handling higher-load or multi-unit projects, our helical screw pile foundations streamline the building control process:

  • Machine-installed using excavators with calibrated torque monitoring – every pile verified on site
  • Comprehensive torque pile logs recording installation torque, depth, pile identification, and performance data
  • Certified load capacity reports generated through deep foundation software
  • Stock sizes from 76R to 140R, manufactured to EN 1090-1 (CE/UKCA) and EN ISO 1461
  • Design life of up to 100 years

This gives your structural engineer and building control officer exactly what they need in one package – no chasing separate piling contractors or waiting on third-party certification.

For further information, please visit our Load Testing page.

Why choose our ground screws for annexes?

  • Nationwide installation service
  • Site-specific load testing with report for building control approval
  • Bespoke structural timber joist bases available
  • Range of ground screw lengths to overcome slope and meet load requirements
  • 15 years of experience working within the granny annexe market
  • CE-approved with a 20-year product guarantee
  • Hot-dip galvanised to BS EN 1461:2009

Frequently asked questions

  • Most garden annexes work well with ground screws and compression load testing. Helical screw piles are worth considering for larger annexe projects with higher structural loads or where building control requires more detailed engineering documentation – they produce comprehensive torque pile logs and certified load capacity reports.

  • Most domestic annexe foundations are installed within a few hours, including fitting the structural timber joist base. There’s no curing time, so your build starts the same day.

  • Yes. Our ground screws provide a fully load-bearing foundation suitable for habitable annexes with all standard services. For projects requiring building control approval, we provide compression load testing with a detailed report – or helical screw pile foundations with certified torque pile logs for higher-load builds.

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