Basement planning conditions by London borough: drainage, SuDS and the start date
How often a basement approval carries a drainage or SuDS condition in each London borough, how often that condition must be discharged before work starts, and what it asks for.
A basement adds habitable space below ground and usually takes garden or hardstanding with it, so the drainage condition arrives with the structural one. Every figure here carries its own sample.
Basements are the one kind of London project where the structural package and the drainage package cannot be separated: the retaining structure, the waterproofing, the lightwells and the surface water all land on the same drawings. This page reads the decision notices for basement schemes across London and reports how often the approval carries a drainage or SuDS condition, how often that condition binds the start date, and what it asks for. Built from public planning records; individual schemes are never named.
Which boroughs attach drainage conditions to basements most often?
The borough table appears once enough basement applications have been read in each borough to report it reliably.
What do the conditions on basements ask for?
The theme breakdown appears once the basement slice is large enough to report it reliably.
What this means for a structural engineer
The condition lands on the applicant, but the documents it asks for are drawn by the engineer or by a drainage consultant the engineer coordinates: attenuation sized against the retained basement footprint, pump and non-return arrangements for the lightwells, a maintenance regime somebody has to own. Where the condition is pre-commencement, the discharge submission is the item holding the start date, and the practice that wrote the planning drawings will be deciding who does it. What a basement impact assessment condition requires covers the structural side of the same approval.
Where does this come from?
We read planning decision notices across London boroughs every morning and pick out the basement schemes by their proposal description. A figure is published only when its own sample clears a floor of 20; where it does not, the cell says so. Only aggregate figures appear here: never a scheme address, an application reference, condition wording or a practice name. See the methodology page or the London-wide picture.
This is the free, public view. Structural engineers use Trails to see the same picture at scheme level: which basement schemes in their boroughs were just approved, the practice behind each one, and which conditions are holding the start date.
See how Trails works for structural engineers →