Substructure
The Building Cost Information Service (BCIS), Elemental Standard Form of Cost Analysis Principles, Instructions, Elements and Definitions 4th (NRM) Edition published by the Royal Institution of Chartered Surveyors (RICS) in 2012, describes the rules for preparing an elemental cost analysis in standard BCIS format.
It defines the term substructure as:
‘All work below underside of screed or, where no screed exists, to underside of lowest floor finishes including damp-proof membrane, together with relevant excavations and foundations (includes walls to basements designed as retaining walls).’
It suggests that the function of the substructure is to, ‘… transfer the load of the building to the ground and to isolate it horizontally from the ground.’
According to BCIS, the substructure includes:
- Foundations up to and including the damp proof course.
- Lowest floor assembly below the underside of the screed or the lowest floor finish.
- Basement excavation.
- Basement retaining walls up to and including the damp proof course.
This a fairly narrower definition which excludes items such as; finishes, basement walls not in contact with earthwork, retaining walls not providing external walls, and so on.
Some much broader definitions consider the substructure to include all works below ground level, although clearly, this is a fairly ambiguous description.
[edit] Related articles on Designing Buildings Wiki
- Basement.
- Basement excavation.
- Basement v cellar.
- Building Cost Information Service.
- BCIS elements.
- Concept structural design.
- Cost planning.
- Deflection.
- Diaphragm wall.
- Elemental cost plan.
- Excavation.
- Footings.
- Groundworks.
- Planning (Subterranean Development) Bill.
- Structure definition.
- Structural engineer.
- Structural principles.
- Substrate.
- Superstructure.
- Types of structure.
Featured articles and news
Embedding AI tools into architectural education
Beyond the render: LMU share how student led research is shaping the future of visualisation workflows.
Why document control still fails UK construction projects
A Chartered Quantity Surveyor explains what needs to change and how.
New planning reforms and Warm Homes Bill
Take centre stage at UK Construction Week London.
A brief run down of changes intentions from April in an onwards.
Reslating an ancient water mill
A rare opportunity to record, study and repair early vernacular roofs.
CIOB Apprentice of the Year 2025/26
Construction apprentice from Lincoln Mia Owen wins this years title.
Insulation solutions with less waste for a circular economy
Rob Firman, Technical and Specification Manager, Polyfoam XPS explains.
Recycled waste plastic in construction
Hierarchy, prevention to disposal, plastic types and approaches.
UK Net Zero Carbon Buildings Standard V1 published
Free-to-access technical standard to enable robust proof of a decarbonising built environment.
Prostate Cancer Awareness Month
Why talking about prostate cancer matters in construction.
The Architectural Technology podcast: Where it's AT
Catch up for free, subscribe and share with your network.
The Association of Consultant Architects recap
A reintroduction and recap of ACA President; Patrick Inglis' Autumn update.
The Home Energy Model and its wrappers
From SAP to HEM, EPC for MEES and FHS assessment wrappers.
Future Homes Standard Essentials launched
Future Homes Hub launches new campaign to help sector prepare for the implementation of new building standards.
Building Safety recap February, 2026
Our regular run-down of key building safety related events of the month.
Planning reform: draft NPPF and industry responses.
Last chance to comment on proposed changes to the NPPF.
A Regency palace of colour and sensation. Book review.