QUICK ANSWER: A basement conversion in Richmond upon Thames always requires full planning permission, since a borough-wide Article 4 Direction (in force since April 2018) removes permitted development rights for all subterranean work — driven largely by the borough's flood risk from the Thames. Freeholder consent is required before you even submit an application, a Construction Management Statement is mandatory, and most properties sit within one of the borough's 87 conservation areas, the highest count in London. Costs typically run £250,000–£600,000 for a full single-storey excavation.
Digging a basement anywhere in London involves paperwork. Digging one in Richmond involves paperwork that specifically exists because the borough sits right next to a river that has, historically, had opinions about where water should go. That's not a throwaway line — it's the actual reason Richmond's basement rules are stricter than almost anywhere else in London. Here's what genuinely matters if you're planning one.
Tip One: Assume You Need Planning Permission, Because You Do
Richmond's borough-wide Article 4 Direction removes permitted development rights for basement work entirely — there's no smaller-scale exemption, no "it's only a small dig" workaround. Every basement excavation in the borough needs full planning permission, full stop, whether it's under a Victorian terrace in Twickenham or a detached property in Ham.
Tip Two: Freeholder Consent Comes Before the Council, Not After
Richmond explicitly requires freeholder consent before a planning application is even submitted, not as a formality that runs alongside it. Sort this first — it's the one step homeowners most often assume they can circle back to later, and it's the one Richmond specifically won't let you skip to the front of the queue.
Tip Three: You'll Need a Construction Management Statement
This is Richmond-specific and easy to miss if your contractor's experience is mostly in other boroughs. The council requires a formal statement covering how you'll manage highway impact, parking, noise, dust, and vibration during construction — and signing up to a Considerate Construction Scheme is expected alongside it. This isn't paperwork for paperwork's sake; Richmond genuinely enforces it.
Tip Four: Respect the Flood Risk, Because the Council Will
Given Richmond's position along the Thames, basement proposals are assessed against the borough's flood-risk policies as standard, not as an exception. Waterproofing specification matters more here than in almost any other London borough — a proper Type C cavity drain system, built to BS 8102, isn't an upgrade in Richmond, it's the baseline any competent contractor should be proposing from the first conversation.
Tip Five: Check Which of the 87 Conservation Areas You're In
Richmond has more conservation areas than any other London borough — 87, covering the vast majority of the borough from Barnes and Kew through Richmond Town, Petersham, and Hammersmith to Twickenham and Teddington. Combined with over 800 listed buildings, this means the external impact of a basement dig — where spoil is removed, where site access sits, how the finished garden is reinstated — gets scrutinised as closely as the excavation itself.
What It Actually Costs
A basement conversion in Richmond typically runs £250,000 to £600,000 for a full single-storey excavation, rising higher for double-level or structurally complex schemes. Costs sit above the general London average, reflecting the additional flood-risk assessment, freeholder consultancy, and Construction Management Statement work required before a spade goes in the ground.
Frequently Asked Questions
Why does Richmond have stricter basement rules than most of London? Primarily flood risk. The borough's proximity to the Thames means subterranean development is assessed against flood-risk policy as standard, which is also the main driver behind the borough-wide Article 4 Direction removing permitted development rights for all basement work.
How long does basement planning permission take in Richmond? Beyond the standard 8-week decision target, Richmond applications commonly take longer given the Construction Management Statement, flood-risk assessment, and freeholder consent that typically need resolving first.
Do I need a Considerate Construction Scheme for a basement conversion? It's expected by Richmond council as part of the Construction Management Statement process, even though it isn't always a strict legal requirement — in practice, contractors who skip it tend to face more scrutiny at application stage.
Thinking About a Basement in Richmond?
Dominant Construction has managed basement conversions and full renovations across Richmond and the rest of West London for over 15 years — FMB-registered, working to JCT contracts, and familiar enough with Richmond's specific requirements to tell you what's realistic before an application goes in.
Call 020 7118 6155 for a consultation, get in touch online, or see recent projects at dominantconstruction.co.uk.