Building new developments on flood plains

This project was a private residential one-off building. There had been concerns that building this house would affect the drainage of the surrounding area and cause a flood issue not to mention concerns from the owners about insuring the property.

The recent floods in the UK, most notably in 2007, 2013 and 2020 across the UK, has resulted in concerns about building on floodplains. Given the increasing demand for new homes coupled with the shortage of land to develop solutions for building on flood plains that provide adequate drainage and elevate the residential floors needs to be accepted and implemented. “The most important measure that can be taken to reduce the impact of flooding is to raise the minimum floor level of the property above expected flood levels” (Office of Deputy Prime Minister, 2003).

In the case of this house, we worked with the architects Think Buildings Ltd on a design that would allow water to run under the house without affecting the structure, local residents or homeowners but that wouldn’t require the expense of putting the house on stilts.

Project Team

Client: Private Client

Architect: Thinking Buildings Ltd

Contractor: Peter Grant Construction

The house is a steel frame structure with engineered timber floor joists, the engineered joists allow for services to be distributed easily throughout the house. The ground floor is a suspended precast concrete plank floor, precast planks were chosen to limit the number of subfloor masonry walls required, which would affect the flow of the floodwater within the flood void.

As the building is within a flood plain, within the subfloor masonry we have a number of openings to allow for the free flow of floodwater through the subfloor void.

With our experience of SuDS, we were able to design voids around and underneath the building so water would be able to run freely under the building – alleviating any flood concerns. The ground level of the building is above the highest anticipated level of water so there is no risk to the homeowner.

This is a reasonably new flood-resistant technology but SWJ Consulting have used this method on several projects to great effect and we consider it a good way of avoiding the expense of stilts.

If you have concerns about flooding or drainage issues with a potential new build or development early engagement with SWJ Consulting will enable us to find you the best solution. Please give us a call on 01993 225085 or email mail@swjconsulting.co.uk