Basement structural method statement
A structural method statement explaining how a basement will be designed and built safely, for planning and party wall purposes.
About this service
A basement structural method statement explains, in a way councils, neighbours and party wall surveyors can follow, how a basement will be built without endangering the house or its neighbours. It covers the structural scheme, the order of excavation, how walls and floors are supported while the ground is open, and how movement will be monitored. Many London councils require one with any basement planning application.
We have prepared 15 basement method statements, mainly for terraced and semi-detached houses in boroughs such as Camden and Kensington and Chelsea, where basement policies are detailed. Typical schemes are single-storey basements under the footprint of a house, often extending under the rear garden, using underpinning to party walls and reinforced concrete retaining walls. Lightwells at the front and rear are usually part of the scheme too.
The statement is usually written at planning stage, before detailed design, so it sets out a realistic scheme and construction sequence rather than final member sizes. It often forms part of a full Basement Impact Assessment and gives party wall surveyors the information they need to agree awards. Fees start from £750 + VAT, fixed in writing before any work starts.
When you need it
- Your council requires a structural method statement
- Party wall surveyors need to understand the construction sequence
- You need an engineer's input at planning stage
What's included
- Outline structural scheme
- Construction sequence and temporary works
- Protection of neighbouring properties
- Monitoring proposals
How it works
- Review site and proposalsWe review the architect's drawings, the existing house and its neighbours, likely ground and groundwater conditions, and the council's basement policy and validation requirements so the statement answers what the council will ask.
- Develop the structural schemeWe set out the permanent structure, typically underpinned party walls, retaining walls, a new slab and beams supporting the house above, with outline sizes and a waterproofing approach.
- Set the construction sequenceWe describe excavation stages, underpinning bays dug in a hit-and-miss pattern, propping at each stage, and how the house above stays supported while the ground beneath it is opened up.
- Protect neighbours and monitorWe describe measures to limit movement to neighbouring properties, such as stiff propping and short bays, and propose monitoring with trigger levels and clear actions if readings are exceeded.
What you receive
Temporary works are where basement risk really sits
Most basement damage happens during construction, not afterwards. Permanent retaining walls are designed for the long term, but each stage of digging leaves soil and walls temporarily unsupported. A credible method statement shows how propping keeps pace with excavation, how underpinning bays are kept short, and what happens if water or soft ground is found. Councils and party wall surveyors look for this detail first.
Because the method statement is an outline, the contractor's temporary works engineer usually develops the propping design further before work starts, and the two must stay consistent. Any change to the sequence on site should be reviewed against the planning version. Our basement conversion guide explains the wider process, from planning through to Building Control sign-off.
Projects that used this service
Frequently asked questions
What is a basement construction method statement?
It is a document describing how a basement will be built safely: the structural scheme, excavation sequence, temporary support, protection of neighbouring buildings and monitoring. Councils use it to judge whether the basement can be built without unacceptable risk, and party wall surveyors use it to understand the effect on adjoining owners.
Does my council need a structural method statement for a basement?
Many London boroughs require one for basement planning applications, either on its own or within a Basement Impact Assessment. Requirements vary, so check the council's validation list or basement planning guidance. We confirm what is needed for your borough before starting work.
Who prepares a basement method statement?
A structural engineer normally prepares it, as it covers the structural scheme and temporary works, often with geotechnical input on ground and groundwater. The contractor's own method statement and temporary works design follow later and should be consistent with the planning version.
How are neighbours protected during basement works?
Through careful sequencing, short underpinning bays, robust propping, and monitoring of neighbouring walls against agreed trigger levels. A schedule of condition before work starts records existing defects. Party wall awards set out each side's obligations, and the method statement gives surveyors the technical basis for those awards.