1,800 sq ft Split-Level New Build in Borehamwood, Hertfordshire
Marshall Construction delivered a technically demanding 1,800 sq ft new build home on a steeply sloping plot in Borehamwood, Hertfordshire. With a 2.2-metre fall from front to rear, the site demanded careful engineering, extensive retaining structures and a split-level design that worked with the natural gradient rather than against it. Delivered in 12 months and sold shortly after completion in October 2025.
FLOOR AREA
1,800sq ft
BUILD LEVELS
5 split levels
DURATION
12 months
Completed
October 2025
Status
SOLD
Site Fall
2.2 metres
Groundworks, Retaining Structures & Site Conditions
The sloping terrain in Borehamwood dictated a split-level design constructed across five separate levels, each connected by short flights of steps. This approach allowed us to work with the natural gradient, minimise excavation, and reduce the overall environmental impact of the build. To stabilise the site, we installed extensive retaining walls with full internal and external waterproofing systems. The structure features concrete cavity walls with integrated insulation and masonry, achieving the required U-values for modern thermal performance.
Ground conditions also required land drains around the entire property, all feeding into a newly designed drainage system. A large existing main drain ran directly through the plot, which our team successfully diverted around the site in coordination with the relevant authorities — a complex piece of utility planning that protected the build programme.
Heavy rain and low temperatures during construction frequently caused water to collect in trenches and slab areas, requiring continuous pumping and careful scheduling. All reinforced concrete slabs across the Lower Ground Floor and Ground Floor were tied into the retaining walls to create a unified structural envelope, with traditional timber joist floors on the remaining levels.
Construction and Building Fabric
The home was constructed using a hybrid approach: blockwork with render at lower levels, and lightweight timber frame for the first and second floors. This combination allowed slim wall profiles while still meeting strict thermal performance requirements.
Selected sections of the exterior were clad in Siberian larch — a material that proved difficult to source due to supply chain disruption from the war in Ukraine. We secured high-quality material and finished it with a clear protective coating to ensure long-term colour stability and weather resistance.
The building incorporates a mix of flat roofs and pitched slate roofs, with multiple complex junctions where blockwork transitions into timber frame. These zones required meticulous alignment with rooflights and Velux windows in the main roof. Detailing included aluminium cappings, parapets, and flat-roof glazing.
Internal Works and Heating System
This Borehamwood project was completed in a single continuous phase, including all first and second fix electrics, plumbing, insulation, rendering, internal finishes and fit-out. The property is heated via an air source heat pump paired with aluminium windows for modern efficiency and durability.
Programme and Outcome
Despite challenging weather, complex engineering and a difficult site, the entire project was completed within 12 months. The home was successfully sold shortly after completion in October 2025.
This build stands out as one of Marshall Construction’s most intricate smaller-scale projects in Hertfordshire, requiring advanced problem-solving, close coordination and a high level of technical execution. It reflects our ability to deliver exceptional results — regardless of size — on sites with significant constraints.
Considering a complex new build in Borehamwood or wider Hertfordshire?
Get in touch with Marshall Construction to discuss your project.