Converting an existing barn into a home requires careful groundwork, particularly when working around older structures and challenging ground conditions.
Sibley Contractors was appointed to undertake the groundworks and foundation preparation for a barn conversion and new extension in Ashill, near Ilminster, Somerset.
The project involved preparing the existing barn, constructing a raft foundation and installing the necessary footings to support the proposed building works.
Working closely with the architect’s drawings and the structural engineer’s requirements, the team completed the groundwork over several weeks, leaving the site ready for the next stage of construction.
The challenge
Working within an existing barn presented several challenges, particularly as sections of the original walls were unstable and required additional care during excavation and foundation preparation.
The team needed to work around the existing structure while making sure the new foundations met the specifications for the planned conversion and extension.
Some areas of the barn also required shoring to provide additional support while work was underway.
Persistent wet weather added further complications, making ground conditions particularly muddy and difficult to manage. Careful planning and a considered approach were essential to keeping the project moving while protecting the existing building.
Preparing the site and existing barn
The first stage involved preparing the barn and surrounding ground for the new foundations. Working within the footprint of an existing structure called for particular attention to the condition of the walls and the areas where excavation was needed.
The team carried out the necessary ground preparation, taking care around the unstable sections of masonry and providing additional support where needed.
Throughout the process, work was guided by the architect’s plans and structural engineer’s specifications. Meeting their standards ensured the site was properly prepared to support the upcoming build and provide a reliable foundation for the barn conversion.
Constructing the foundations
With the initial preparation complete, attention turned to constructing the raft foundation and associated footings.
A raft foundation provides a reinforced concrete base that distributes the weight of a building across a wider area. For the Ashill project, the foundation needed to be constructed in accordance with the structural engineer’s design, taking account of the existing barn and planned extension.
One of the key milestones was getting the new steelwork into position ahead of the concrete pour. Accurate placement and coordination at this stage were essential to ensuring the foundations met the specifications.
Despite the challenging weather and restrictions of working within an existing building, the team completed the foundation works successfully.
The result
Over the course of a few weeks, Sibley Contractors transformed a wet, muddy working area into a clean, prepared site with the foundations in place for the next phase of the build.
All groundwork and foundation construction was completed, with the finished work receiving full sign-off from the council's building inspector.
The client was pleased with the outcome, particularly the progress made in preparing the existing barn and creating a clean, dry working environment. With the structural groundwork completed and approved, the project was ready to move forward into the construction stage of the barn conversion and extension.
Planning a barn conversion or building project?
Sibley Contractors provides professional groundworks, excavation and foundation services across Somerset, Devon and the wider South West.
Get in touch with Sibley Contractors to discuss your project and request a free quote, or explore our recent projects to see more examples of our groundwork services.
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Posted by Luke Clark on October 21st 2026
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