Building Height Assessment
Precise, RICS-regulated vertical measurement across London, Surrey and Sussex — giving developers, freeholders and building managers the exact height data they need for planning, permitted development and Building Safety Act compliance.
Accurate building heights, measured to a defined datum
A building’s height sounds simple to pin down — until it decides whether your scheme needs prior approval, whether a block falls inside the Building Safety Act 2022 regime, or whether a neighbour’s right to light claim holds up. Get the figure wrong and the consequences are real.
Blackacre carries out professional building height assessments that produce a defensible, measured figure — captured with 3D laser scanning, drone (UAV) survey and total-station equipment, referenced to a clear ground datum, and delivered as a dimensioned cross-section and CAD drawing you can put in front of a planning authority or the Building Safety Regulator.
When you need a height assessment
Planning & permitted development
Confirm ridge, eaves and storey heights against local height limits and permitted development thresholds before you submit — and evidence them if challenged.
Building Safety Act 2022
Establish whether a block crosses the 11m or 18m thresholds that trigger the higher-risk and relevant-building regimes and leaseholder protections.
Rights of light & massing
Feed accurate heights and massing envelopes into right to light and daylight & sunlight analysis, and into party wall and expert witness work.
The Building Safety Act 2022 thresholds
For owners and managers, the first question is which regime a building falls into. Two height-based definitions matter, and a building needs to meet either the metre or the storey test — not both.
Higher-risk building
At least 18 metres in height or at least 7 storeys, and containing at least two residential units. These fall within the higher-risk regime overseen by the Building Safety Regulator.
Relevant building
At least 11 metres in height or at least 5 storeys, containing at least two dwellings and not leaseholder-owned. This is the threshold for the leaseholder protections in Schedule 8.
How the height is measured matters. Height is taken from ground level to the finished floor surface of the top storey — and on sloping ground, from the lowest part of the ground next to the building. When counting storeys, a basement below ground level and roof-top plant rooms are excluded. A few centimetres can move a building across a threshold, which is exactly why a measured assessment — not an estimate — is worth having.
For a fuller walk-through, see our guide: Building Height Assessments — a guide to the Building Safety Act 2022. You can also check the government’s higher-risk building criteria.
How we measure it
Every assessment is captured with survey-grade instruments and tied to a defined ground datum, so the figure is repeatable and defensible:
• 3D laser scanning for millimetre-accurate point clouds of the elevation
• Drone / UAV survey to reach ridges, parapets and roof plant safely
• Total station & levelling to establish ground level and datum
• Deliverables: measured overall height, floor-to-floor and storey heights, a dimensioned cross-section and CAD drawing
Height work sits alongside our wider measurement services — measured building surveys, 3D laser scanning, drone surveys, topographical surveys and 3D modelling — so a height assessment can be delivered on its own or as part of a full measured package.
Why Blackacre
RICS-regulated
An independent, RICS-regulated practice — our figures and drawings are prepared to a professional standard and stand up to scrutiny.
In-house capture
Laser scanning and drone capability in-house, so we control accuracy end to end and can mobilise quickly across London and the South East.
Joined-up advice
Height data that feeds directly into planning, Building Safety Act, rights of light and party wall work — one team, no gaps between reports.
Key contact
Ben Salvage MRICS C.Build E MCABE
Director | Chartered Building Surveyor
Ben leads Blackacre’s building surveying and measurement work. Get in touch for a building height assessment across London, Surrey and Sussex.
Need an accurate building height?
Tell us the building and what the height is for — planning, Building Safety Act, rights of light or party wall — and we’ll advise on the right survey and turn a measured assessment around quickly.