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The flat-and-couple borough, and why it hardly ever overcrowds

Census 2021 counted 137,393 households in Wandsworth, the third largest of the thirty-three London local authorities behind Croydon and Barnet. 48.1% of them are in a purpose-built block of flats or tenement and a further 17.7% are part of a converted or shared house, seventh highest in London. 22.2% are terraced. Only 7.0% are semi-detached, twenty-fourth of thirty-three, and 2.2% are detached. Wandsworth's own Joint Strategic Needs Assessment puts it more bluntly: 'Of the almost 150,000 properties in Wandsworth, over two-thirds are flats, and almost a third of the households rent privately'.

The household size distribution is the unusual part. 34.1% of Wandsworth households contain exactly two people, second only to the City of London and above every other borough. 35.8% of homes have two bedrooms, sixth highest in London, and only 21.6% have three, twenty-sixth of thirty-three. Households of six, seven and eight or more are all well below the London average.

The result is that Wandsworth is one of the least overcrowded boroughs in London. Only 6.4% of households sit at an occupancy rating of -1 on the bedroom standard, twenty-fifth of thirty-three, and 1.2% at -2 or less, twenty-sixth. Compare that with Newham at 15.9% and 5.7%. This matters practically: the duty-cycle failures that dominate our work in Ealing or Newham, where systems run at double their designed load, are simply not the Wandsworth pattern.

What replaces it is a shared-services problem. In a two-bed flat in a purpose-built block, the cold feed comes off a communal riser, the stopcock that isolates your flat is frequently on a landing rather than under your sink, and the flat that floods is usually not the flat where the fault is. 36.3% of Wandsworth households rent privately, seventh highest in London, so the person standing next to the water at two in the morning is often a tenant who has never seen the isolation point and cannot authorise spend. We isolate first, stabilise, then quote to whoever is actually paying.

Nine Elms, Battersea and a borough with more heat networks than most

3.9% of Wandsworth households are on a district or communal heat network only, thirteenth in London against a London figure of 3.4% and an England figure of 0.9%. Only 69.7% run on mains gas alone, nineteenth of thirty-three and below the London average, while 13.3% heat on electricity only, eleventh in London.

The Census does not say where inside the borough that 3.9% sits, but the largest single piece of verified heat network infrastructure here is in the Nine Elms and Battersea corridor. The Battersea Power Station development states that its energy centre sits 'ten metres below ground and directly in front of the iconic Power Station building', comprises 'three combined heat and power gas fired (CHP) engines (two 2MWe and one 3.3MWe), three 10MWth gas fired boilers' and is 'split over two levels, totalling 73,000 sq ft', 'with the potential to supply energy to residents and businesses across the wider Nine Elms regeneration area'.

For a resident of a building on that kind of arrangement the plumbing looks nothing like a house. There is no boiler. There is a heat interface unit, a set of communal pipework you do not own, and a plant room you have no key to. When the network goes down you lose heating and hot water at the same time and there is nothing inside the flat to fix. The useful thing an engineer can do at midnight is confirm the fault sits upstream of your heat interface unit, get you hot water another way where that is possible, and give you a written report the managing agent has to act on. When the fault is your own heat interface unit, we repair it on the visit.

Wandsworth also states that it owns 148 high-risk residential buildings, defined on the same page as buildings with 'seven storeys or more, or are greater than 18 metres in height'. That is a substantial high-rise portfolio, and it produces the classic riser and communal tank failures alongside the newer heat network faults. We are not publishing a total council homes figure, because the number commonly repeated online does not appear in any council document we could read.

Licensing arrived in 2025, and the map has already changed once

Wandsworth spent years as one of the London boroughs with no additional or selective licensing at all. That is no longer true, and anyone working from an older understanding of the borough is now wrong.

Additional HMO licensing applies borough-wide. The public notice states that 'The Designation is made on 22 July 2024 and shall come into force on 01/07/2025', that it 'shall cease to have effect on 30/06/ 2030' and that it 'shall apply to the entire area of the London Borough of Wandsworth as delineated in red on the map in annex A'. It catches 'all Houses in Multiple Occupation (HMOs) as defined by section 254 of the Act that are occupied by 3 or more persons comprising 2 or more households'.

Section 257 buildings are treated differently here from Ealing and Haringey. Wandsworth states that 'The additional HMO scheme will not apply to certain converted flats or blocks, known as Section 257 HMOs (self-contained flats). However, if a converted block falls within the selective licensing designation, each individual flat within the block will require its own selective licence, unless it is otherwise exempt'. So the building is not licensed but the individual lettings inside it may be, depending which ward it is in.

Selective licensing runs in two designations. The first took effect in July 2025 and covers Furzedown, Tooting Bec, Tooting Broadway and South Balham. The second, 'known as the London Borough of Wandsworth Designation 2 for Areas for Selective Licensing 2026', came into force on 1 April 2026, ceases on 31 March 2031, and covers East Putney, Northcote and West Putney. Seven wards in total, split across two schemes with different timelines and different early bird windows. The council states that the early bird discount for designation 2 'will run from 1 April 2026 to 1 October 2026' and that the discount for the first designation and the additional scheme 'ended on 31 December 2025'.

One oddity worth knowing if you are dealing with the council: both Wandsworth designation notices give a Merton contact address in Morden. Private sector housing here is run as a shared service with Merton, so a Wandsworth licensing enquiry may be answered from another borough's civic centre. That is normal, not an error.

On penalties, both notices state that the council may impose 'a financial penalty of up to £30,000' as an alternative to prosecution, and that a licence condition breach carries 'a maximum fine of £5,000 per breach'. Section 249A(4) of the Housing Act 2004 as in force sets the ceiling at £40,000, raised from £30,000 on 1 May 2026, so Wandsworth's published figure predates the uplift. We give you both, attributed.

Basements, 46 conservation areas and no HMO Article 4 at all

Wandsworth states that it 'currently contains 46 conservation areas which range from historic villages such as Battersea Square' and that it 'has around 500 listed buildings which include a wide range of building types and ages that are considered to be of national importance'. Forty-six is a high count for a borough this size and it covers a great deal of the Victorian terrace stock in Battersea, Clapham, Balham, Wandsworth Town and Putney.

What Wandsworth does not have is an Article 4 direction on HMO conversion. Its published Article 4 list covers change of use from Class E commercial premises to dwellinghouses and from B1a offices to dwellinghouses, and nothing on C3 to C4. That is the reverse of Croydon, Ealing and Lewisham, all of which have removed those permitted development rights borough-wide. It is a real difference and landlords should not assume the Ealing or Lewisham position applies here.

Basements are the other distinctive planning constraint, and it is one that lands squarely on plumbing. Wandsworth's local plan carries a specific basements policy, LP6 Basements and Subterranean Developments, and its application requirements state that a Construction Method Statement for a basement must cover 'a ground and hydrological condition report dealing with groundwater flow ensuring structural stability during excavation', with the Construction Management Plan 'signed by a Chartered Civil Engineer (MICE) or Chartered Structural Engineer (MI Struct. E.)'. The Local Plan was adopted on 19 July 2023 and a Partial Review was adopted on 4 March 2026, which did not supersede LP6.

Basement flats and converted lower ground floors are where water ends up in this borough, and where the consequences are worst. A riser leak six floors up drains downwards. A blocked shared stack backs up into the lowest connection. A surcharging drain in heavy rain finds the lowest gully. On flood risk more broadly, the Thames Estuary 2100 Wandsworth to Deptford Policy Unit identifies 'tidal flooding from the Thames upriver (west) of the Thames Barrier' and 'fluvial flooding from the River Wandle', with the area protected by the Thames Barrier and other tidal defences. Wandsworth's own strategic flood risk assessment work confirms the tidal modelling and the Environment Agency's Wandle modelling.