At H Fraser Consulting Ltd, we have extensive experience helping homeowners navigate the planning process for basement developments – particularly in areas with strict regulations like the London Borough of Camden. Our team recently supported a private homeowner in extending their five-storey semi-detached property, which involved creating a new basement beneath the ground-floor flat. The project included removing an old conservatory and building two ensuite bedrooms with a central lightwell, plus a kitchen with a green roof and terrace above.
Working alongside Jon Smithson from Ground and Project Consultants Ltd, together we carried out a Basement Impact Assessment (BIA) to meet Camden’s planning requirements. This involved a Ground Movement and Building Damage Assessment as well as hydrology and geotechnical studies to ensure the design was safe and compliant. Given Camden’s rigid basement extension guidelines, our in-depth understanding of these requirements helped move the application smoothly through the approval process.
Our work included:
- Desk study & site investigation – Borehole drilling confirmed the site’s ground conditions, revealing Made Ground, Head, and London Clay Formation with no aquifer present. London Clay was deemed stable for construction.
- Ground movement analysis – We assessed the potential impact on surrounding buildings, rating structural damage risk as negligible to very slight.
- Flood Risk Assessment (FRA) – The site had a medium risk of pluvial and sewer flooding, so we designed mitigation measures to protect the development.
Engineering Solutions
To ensure a safe and resilient basement, we recommended:
- Reinforced concrete retaining walls, designed to withstand hydrostatic pressure and buoyant uplift.
- A Grade 3 waterproofing system to prevent groundwater ingress.
- A sump and automatic pumping system to manage any water accumulation in the lightwell.
- A Sustainable Drainage System (SuDS) to prevent excess runoff from impacting the sewer network. This directed rainwater from impermeable surfaces and the green roof to a dedicated drainage system
The Outcome
Thanks to our thorough assessments and strategic mitigation measures, the BIA confirmed that the development posed no significant flood risk. With our expertise, the project gained planning approval, ensuring the homeowner could proceed with their dream basement extension.
How We Can Help
At H Fraser Consulting Ltd, we specialise in securing planning approvals for complex projects, from small scale basement developments to larger commercial and industrial developments. If you’re considering a similar project, our team can help you navigate planning regulations, mitigate risks, and provide expert hydrological and geotechnical assessments.
Need help with your basement project? Get in touch with us today!
