Design & Build Foundation Package

Work Type

Design & Build Suspended Piled Raft Foundation, Integrated Reinforced retaining wall fixed into 300mm RC slab for Huf Haus Showroom in Weighbridge.


Huf Haus


Weybridge, Surrey, KT13

Project Overview

Our client installed a pre-fabricated Huf Haus built in Germany and imported to UK to construct. The house itself is Huf’s first UK showroom. Speedeck Foundations were engaged by Projekt Plus to produce a cost-effective design and build foundation that was built to a high quality with high tolerances.

Site Review

The site is based in Weighbridge just off the river Wey, surrounded by established trees so a cost-effective foundation solution had to be developed that:

  • Took into account that the lower level of site is subject to seasonal flooding from the nearby river.
  • Enabled construction works to be carried out that would mitigate any damage to the trees and numerous established shrubs around the perimeter of the site.
  • Reduced the risk of potentially contaminating the nearby river Wey.

The soils of the site can be described as topsoil, made ground, Alluvium, Kempton Park Gravel over Bagshot formation.


Upon invitation to tender our engineer made a site visit to complete our own site appraisal to understand the constraints of the site and extent of the TPO’s and potential flood risk from the river. Based on the original concept produced by our client we created a 3D design model of the proposed foundation solution using state of the art foundation modelling software.

By collaborating with our client, SPEEDECK specified an economical continuous 300mm reinforced concrete raft that was to be built up from the lower level to give a 1.3mtr clear void to protect the foundation from potential flooding from the river.

The raft was to be supported by 29 no. 273mm steel cased driven piles to reach a set within the Kempton Park Gravel at 6.5mtrs. This piling method was selected due to: the depth of the piles required, it is quieter than alternative methods available, with the additional benefit of reducing the possibility of contaminating the nearby river due to the controlled nature associated to this method.

The level differences of the site and the flood zone at the lower level meant that we had to extend the piles installed on the lower platform to 400mm squared reinforced 1.3mtr high concrete columns to underside of the soffit to facilitate the formation of raft construction including a downstand detail to the balcony area.

Skills Applied

  • Structural and Geotechnical Engineering
  • 3D design modelling
  • Reinforced concrete columns
  • Integrated reinforced retaining wall
  • Falsework to create suspended RC slab
  • Formwork Timber shutters and downstand details
  • Concrete placing with F1 and F3 finishing