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Class H: Industrial and warehouse buildings
Class H permits the erection, extension or alteration of an industrial building or warehouse. The development must be within the curtilage of an existing industrial building or warehouse and must be used for the undertaking in the way required by the Class H conditions.
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Permitted development can avoid a full planning application, but only if the right applies and every relevant limit and condition is met. Planning Geek can check the planning history, Article 4 directions and other restrictions, and help with a lawful development certificate or prior approval where needed.
A new building is limited to 100 square metres on protected land such as conservation areas, National Parks, National Landscapes, the Broads and World Heritage Sites, or on an SSSI, and 200 square metres elsewhere. An extension has different limits: on that protected land it is 10% or 500 square metres, whichever is less; on an SSSI it is 25% or 1,000 square metres, whichever is less; elsewhere it is 50% or 1,000 square metres, whichever is less.
For a new building, the height limit is 5 metres where it is within 10 metres of a curtilage boundary. Elsewhere it is the height of the highest building within the curtilage or 15 metres, whichever is lower. For an extension or alteration, the height limit is 5 metres within 10 metres of a boundary and otherwise the height of the building being extended or altered. No part of Class H development may be within 5 metres of any curtilage boundary.
The development must not reduce the space available for parking or turning vehicles and Class H cannot be used within the curtilage of a listed building. The new or altered building must remain tied to the industrial or warehouse undertaking. Employee facilities have additional restrictions, including limits on use at night and where dangerous substances are present. On protected land such as conservation areas, National Parks, National Landscapes, the Broads and World Heritage Sites, the external materials must have a similar appearance to the relevant existing building. Class H itself has no prior approval procedure.
You can check the legislation below for industrial buildings or warehouses. If you need any assistance, please contact us.
Industrial building legislation
Class H – extensions etc of industrial and warehouse
Permitted development
H. The erection, extension or alteration of an industrial building or a warehouse.
Development not permitted
H.1 Development is not permitted by Class H if—
(a) the gross floor space of any new building erected would exceed—
(i) for a building on article 2(3) land or on a site of special scientific interest, 100 square metres;
(ii) in any other case, would exceed 200 square metres;
(b) the gross floor space of the original building would be exceeded by more than—
(i) in respect of an original building or a development on article 2(3) land, 10% or 500 square metres (whichever is lesser);
(ii) in respect of an original building or a development on a site of special scientific interest, 25% or 1,000 square metres (whichever is the lesser);
(iii) in any other case, 50% or 1,000 square metres (whichever is the lesser);
(c) the height of any part of the new building erected would exceed—
(i) if within 10 metres of a boundary of the curtilage of the premises, 5 metres;
(ii) in all other cases, the height of the highest building within the curtilage of the premises or 15 metres, whichever is lower;
(d) the height of the building as extended or altered would exceed—
(i) if within 10 metres of a boundary of the curtilage of the premises, 5 metres;
(ii) in all other cases, the height of the building being extended or altered;
(e) any part of the development would be within 5 metres of any boundary of the curtilage of the premises;
(f) the development would lead to a reduction in the space available for the parking or turning of vehicles; or
(g) the development would be within the curtilage of a listed building.
Conditions
H.2 Development is permitted by Class H subject to the following conditions—
(a) the development is within the curtilage of an existing industrial building or warehouse;
(b) any building as erected, extended or altered is only to be used—
(i) in the case of an industrial building, for the carrying out of an industrial process for the purposes of the undertaking, for research and development of products or processes, or the provision of employee facilities ancillary to the undertaking;
(ii) in the case of a warehouse, for storage or distribution for the purposes of the undertaking or the provision of employee facilities ancillary to the undertaking;
(c) no building as erected, extended or altered is used to provide employee facilities—
(i) between 7.00pm and 6.30am, for employees other than those present at the premises of the undertaking for the purpose of their employment; or
(ii) at all, if a quantity of a dangerous substance is present at the premises of the undertaking in a quantity equal to or exceeding the quantity listed in the entry for that substance in Parts 2 or 3 of Schedule 1 to the Control of Major Accident Hazards Regulations 1999;
(d) any new building erected is, in the case of article 2(3) land, constructed using materials which have a similar external appearance to those used for the existing industrial building or warehouse; and
(e) any extension or alteration is, in the case of article 2(3) land, constructed using materials which have a similar external appearance to those used for the building being extended or altered.
Interpretation of Class H
H.3 For the purposes of Class H, where 2 or more original buildings are within the same curtilage and are used for the same undertaking, they are to be treated as a single original building in making any measurement.
H.4 For the purposes of Class H—
“dangerous substance” has the meaning given in regulation 2 of the Control of Major Accident Hazards Regulations 1999;
“employee facilities” means social, care or recreational facilities provided for employees of the undertaking, including crèche facilities provided for the children of such employees; and
“original building” does not include any building erected at any time under Class H.
Current legislation: Part 7 of Schedule 2 on legislation.gov.uk
Industrial building Page Updated: 23rd September 2026