Basement surveys that inform the build

Replace assumptions with site information before committing to a basement design. We help define and coordinate the investigation inputs for your construction package, so foundations, ground conditions, drainage and access inform the work from the start.

Discuss your project

Turn site information into construction decisions

We review the information available for the proposed basement against the work being planned. Foundation details inform the support strategy; ground and water conditions influence excavation and waterproofing; existing service routes affect where construction can proceed.

Where investigations form part of our agreed package, we organise the access and construction input they need, then incorporate the findings into the works. Specialist surveys and engineering assessments are undertaken by the appropriately appointed professionals.

Blockwork walls and scaffolding around a basement opening
Core drilling equipment positioned over a concrete slab

Different investigations answer different questions

  • Measured and level information: establishes the relationship between existing floors, the proposed basement, external ground and access points.
  • Foundation investigations: help establish the depth and form of existing support where the engineer needs that information.
  • Ground and groundwater investigations: inform the excavation design and assessment of water conditions.
  • Drainage and service investigations: establish routes, levels and obstructions that can conflict with the proposed structure.
  • Existing building investigations: address hidden construction and materials that may be disturbed by the works.

The scope follows the site's unanswered questions. A measured survey alone cannot establish what lies beneath a neighbouring foundation.

Use the results before fixing the method

An unexpected drain can affect a wall position. Different foundation depths can change the excavation sequence. Groundwater can alter the temporary works and water management approach. We bring these findings into the structural and excavation package and the waterproofing design, identifying decisions that require the engineer's or another specialist's review.

The same evidence may support planning submissions. Camden's BIA process and Westminster's basement methodology requirements both call for site-specific technical information.

Plan intrusive work around the property

Trial pits and opening-up works need defined locations, access and a safe method. Existing services must be addressed before excavation, and relevant asbestos information must be available before disturbing suspect building fabric. Access limits are recorded because an uninspected area leaves a question unresolved.

Contact us about the investigations needed for your basement construction.

Frequently asked questions

Can existing surveys be used?

Yes, where they cover the proposed works and remain relevant. Their extent, assumptions and access restrictions need checking. A report for a previous layout or shallower excavation may leave important gaps for the current scheme.

Are trial pits and boreholes interchangeable?

No. A trial pit may expose a foundation or local construction, while a borehole can investigate the ground at depth. The engineer or ground specialist determines which investigation will answer the project's particular questions.

Does a dry cellar mean there is no groundwater risk?

No. The proposed excavation may extend below the existing floor and encounter different conditions. Groundwater information needs to relate to the intended basement and its design, rather than relying solely on the cellar's present appearance.

Does a normal asbestos management survey cover structural alterations?

Not necessarily. Management surveys support normal occupation. Refurbishment or demolition work can require intrusive investigation of hidden materials in the affected area before structural work begins. The appropriate survey scope must match the planned disturbance.

Do surveys remove all risk of unexpected conditions?

No. They reduce uncertainty within their scope and access limits. If excavation reveals a material difference, the finding needs assessment and any necessary design or method change before the affected work continues.

Basement design and planning in London

Basement design and planning support within a complete construction service, connecting layouts, structural design, waterproofing and borough requirements.