Tall buildings in London: definition, location and impacts

Tall building policy London Plan applications turn on a question that national policy does not answer: what counts as tall. The London Plan hands that decision to each borough, requiring the development plan to define a height threshold for specific localities and to identify where tall buildings may be appropriate. The threshold cannot be less than six storeys or 18 metres measured from ground level to the floor of the uppermost storey.

So the first piece of work on any tall building scheme is not a view study. It is reading the borough's own definition and its tall buildings map, because if your site is not in an identified location the policy says the proposal should not be considered acceptable, and no amount of visual analysis cures that.

How a tall building is defined locally

Policy D9 part A puts three duties on boroughs. Define what is a tall building for specific localities. State the height that would be considered tall. Identify the locations where tall buildings may be appropriate, shown on maps in the development plan.

The results vary widely. One borough may set its threshold at 18 metres across the whole area, another at 30 metres in a town centre and 15 metres elsewhere, another by storeys rather than metres. Read the definition in the adopted plan and any emerging plan, and note which document the council will actually determine the application against.

Where a borough has not yet defined a threshold or mapped locations, the position is messier and the default of 18 metres or six storeys becomes the working definition. That is an argument worth having at pre-application rather than at committee.

Height is measured to the floor level of the uppermost storey, not to the top of a plant enclosure or a parapet. Applicants and objectors both get this wrong, usually in the direction that suits them.

Whether the location is identified in the plan

Part B is the gate. Tall buildings should only be developed in locations identified as suitable in the development plan. Not "preferably". Identified.

If your site is inside a mapped location, the argument moves on to impacts. If it is not, you are running an argument that the development plan is out of date, or that the scheme is an exception justified by other material considerations, and that is a materially harder case. An Opportunity Area allocation helps but does not substitute for a tall buildings designation.

Height and capacity are not the same question either. A design-led assessment of capacity under policy D3 can support a taller scheme within an identified location, and the method for that is covered in optimising site capacity under policy D3. It does not create a location where the plan has not identified one.

The visual impact tests and the viewpoints

Part C of the policy groups the impacts under three headings, and visual impact carries the most material.

Six things have to be addressed. Views from the immediate streets and public spaces. The effect on the skyline and on the character of the wider area. Architectural quality, detailing and materials at both distance and close range. The effect on heritage assets, including World Heritage Sites, strategic views and protected vistas. And the cumulative effect of the proposal together with other consented and emerging tall buildings.

That last point is the one most often underdone. A single tower in isolation may read acceptably while the same tower as the fourth in a cluster does not, and the Greater London Authority expects consented schemes to be modelled in the baseline.

The evidence comes through a Townscape and Visual Impact Assessment with accurate visual representations from an agreed viewpoint list. Agree the viewpoints in writing with the borough and, where the scheme is referable, with the Greater London Authority, before the images are produced. Reworking verified views after a consultation response is expensive and slow.

Materials matter more on a tall building than on anything else, because the building is read from three distances: the street, the middle ground and the skyline. Provide a bay study, a materials schedule and physical samples, and expect a condition requiring sample panels on site.

Functional impact: entrances, servicing and transport

Functional impact asks whether the building works as a building and whether the transport network can carry it.

The practical content is the ground floor and the basement. Where is the residential entrance, where does servicing happen, how do refuse vehicles turn, where do cycles go, how does the building meet the pavement, and is the frontage active or a run of plant louvres. Tall buildings concentrate a large population onto a small footprint, and the servicing design is what fails first.

On transport, the questions are station capacity at peak, bus capacity, cycle parking numbers against the London Plan standards, and whether the site's public transport accessibility level supports the proposed car parking. Where the scheme is large enough to need play provision, the child yield calculation and the provision it generates belong in the pack rather than appearing as an afterthought at stage one.

Environmental impact: wind, daylight and glare

Three environmental matters come up on almost every tall building application.

A Wind Microclimate Assessment should be commissioned early, because the mitigation is architectural. Canopies, podium setbacks, screens and planting all change the massing, and finding out at stage two that the entrance sits in an unsafe wind condition means redesigning the base of the building.

Daylight and sunlight in dense London conditions needs the BRE guidance applied with judgement rather than as a pass or fail arithmetic test, and the approach that holds up at appeal is set out in applying BRE 209 daylight guidance in dense London.

Fire safety is not listed under environmental impact but it governs the design all the same. Buildings of 18 metres or more fall within the higher-risk regime, the Building Safety Regulator is a statutory consultee at Planning Gateway One, and a Fire Statement must be submitted with the application under article 9A of the Development Management Procedure Order 2015. It has to be prepared by someone with the necessary fire engineering competence, so an AI-assisted draft is a starting point for that person rather than a substitute.

Public access and the top of the building

Part D of the policy asks for free to enter publicly accessible areas within tall buildings where appropriate, and says the opportunity should be taken to make the top of more prominent buildings publicly accessible.

Treat this as a design question with a management answer. A viewing level needs its own lift strategy, its own means of escape, its own servicing and a security interface with the residential or office floors above and below. Schemes that offer public access without resolving those four things get a condition requiring a management plan and then quietly fail to deliver.

Where public access at the top is not practical, say why, and offer something at the base instead. An open ground floor with a public through route is worth more to the public than a viewing gallery open two days a month.

Assembling the evidence package

A referable tall building application typically carries a planning statement, a design and access statement with a townscape and visual impact assessment and verified views, wind microclimate, daylight and sunlight, solar glare, heritage assessment, transport assessment and travel plan, energy statement, whole life carbon assessment, fire statement, play space, and a basement impact assessment where there is deep excavation.

Order the work so the massing-critical studies land first. Wind, daylight and verified views can all force a change to the envelope, and they cost less to run on a sketch massing than on a coordinated Stage 3 design. Everything else can follow the fixed envelope.

Browse all 66 PlanScope report types to see which documents a tall building application is likely to need.

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