Measuring building height
Taller buildings have more stringent regulations regarding fire safety and maintenance due to potential evacuation challenges. This means that knowing a building’s height is critical for the building’s ‘responsible party’. This is usually the managing agents or building owner. If a building is self managed, that could include the directors of a freehold company or any RTM (right to manage company).
Why do I need to know the height of my building?
Under the Building Safety Act 2022, a building’s height determines the category it falls within under the legislation. The applicable guidelines for compliance must then be followed.
As a building owner, you need to understand the obligations you have. As a resident, or leaseholder, you need to understand your rights. If you’re a resident of high rise building, take a look at the Your Home, Your Safety guide.
What is the building safety act?
The Building Safety Act came into force in October 2023. It is a health and safety law that applies to all buildings in England (and only in part to Wales and Northern Ireland). The Act concentrates on building structural safety and fire safety only.
For more information, take a look at the RICS FAQs about the Building Safety Act. You can read it in full on the Government website.
What does the building safety act say about building height?
For building owners, the Act states they will be required to manage safety risks, with clear lines of responsibility for safety during design, construction, completion and occupation of high-rise buildings.
It is of particular importance to leaseholders, as it means they are no longer considered to be the first party responsible for paying for historical safety defects. It also means residents in high-rise buildings have more say in how their building is kept safe.
What are the different categories of building height?
Buildings can be designated as a relevant building or a high-risk building (or neither). The inspection routines for fire doors and other core safety aspects are subject to these categories:
- A high-risk building is at least 18m in height or has at least 7 storeys’, and ‘contains at least 2 residential units’ (a ‘dwelling’ or any other ‘unit of living accommodation’).
- A relevant building is at least 11 metres tall, or has at least five storeys, contains at least two dwellings, is not leaseholder-owned.
- It could be neither of these if the building has two or more sets of domestic premises.
What requirements are there for buildings over certain heights?
Building owners must ensure that specific procedures are in place for buildings within each category:
How do I accurately measure my building’s height?
This is not as straightforward as it may initially appear. The Safety Act states that the height of a building is to be measured from ground level, to the finished surface of the floor of the top storey of the building (ignoring any storey which is a roof-top machinery or plant area or consists exclusively of machinery or plant rooms).
Importantly, ground level may not be pavement level. It may be a lower ground level, if there is a lightwell or the property is on a sloping site. The diagram below explains this:
How do I count building storeys correctly?
To determine the number of storeys a building has, you should ignore:
- Any storey which is below ground level, ie, wholly a basement, with the ground against the external walls.
- Any storey which is a roof-top machinery, roof-top plant area, or consists exclusively of roof-top machinery or roof-top plant rooms.
- Any storey consisting of a gallery, with an internal floor area that is less than 50% of the internal floor area of the largest storey vertically above or below it which is not below ground level.
More information about ‘Counting storeys and measuring height’. This also includes useful diagrams.
Get in touch with Collier Stevens for expert advice
If you’d like to ensure the height of your building is measured correctly, get in touch with party wall surveyors in London for expert advice. The Collier Stevens team, experts in party wall matters and building surveys, can help you do this, and provide advice regarding the correct procedures you need in place for the height of your building.
Steven Way
Steven Way BSc MIHEEM MFPWS MRICS is the Practice Principal and is a Chartered Building Surveyor. With over 35 years as a practicing surveyor, Steve has a wealth of experience and expertise in both residential and commercial building surveying, party wall advice and disabled access auditing. He has also built his reputation as an expert witness.