£5M Two Storey Basement and Refurbishment

Located on the banks of the river Thames near Wargrave, the private owner of this property wanted to create a stunning family home with additional living space, a gym, office and store, wine cellar and leisure facilities.

The owner wanted a complete refurbishment of the existing barn conversion. Rearrangement of internal walls and unusually, an addition of a two storey submerged basement extension. With the roof terrace above taking advantage of the picturesque views down to the river Thames.

Our Brief

Appointed by the Project Manger, our brief was to carry out the full structural design, everything from substructure and temporary works, strengthening of the existing barn, retaining walls, designing the two storey basement and assessment and design of the existing roof.  In addition the design of up to 20 internal beams and trusses.

Drainage and treatment plant also fell within our scope of works.

Design Challenges

One of the most challenging parts of this design was the temporary works to retain the existing barn conversion on the top of the hill, whilst the basement excavations were carried out behind the barn.



Temporary works Revit

The whole rear of the barn was supported on steel frames, on temporary piles, and plunge columns – 8m off the ground.

Temporary works Rebar

Stability frames were designed as we had to suspend the original barn in mid air whilst excavations were carried out underneath.

Basement Revit

Typical Details

Temporary works Revit


We had to use Platipus Anchors to weigh the pile back to reduce their size.  Size was a big issue, everything had to be as small as possible to gain every 10mm.

Gallery Area – Temporary Structure

Temporary works BIM Revit


Temporary works



Revit details BIM

“Gallery” or “out crop” where they had windows all around, was suffering as it was spreading – we had to strengthen that, which in turn meant we had to strengthen the exposed trusses on the first floor. Decorative cast iron brackets were used.



3D Revit Image

Basement Revit