Part 7 permitted development for commercial extensions

Part 7 of Schedule 2 to the General Permitted Development Order 2015 lets some commercial buildings be extended without a planning application, and the limits are tighter than most occupiers expect. A shop can usually add the lesser of 50 m² or 25 per cent of the gross floor space of the original building. An industrial or warehouse building gets far more room, the lesser of 1,000 m² or 50 per cent. Offices sit awkwardly, because the class written for retail and financial or professional services was never drafted to cover them. Those figures and the exclusions around them are the whole of the Part 7 commercial extension permitted development question, so work through them in order before anyone orders steel.

Which non-domestic uses Part 7 reaches

Part 7 is a collection of classes, each tied to a type of premises. One class deals with extensions and alterations to shops and to financial or professional services establishments. Another pair deals with industrial and warehouse premises. Further classes cover schools, colleges, universities and hospitals, hard surfaces, click-and-collect points, loading bays and the installation of plant on industrial land.

The Part has been amended repeatedly and some classes have been re-lettered along the way, so quote the limits from the current consolidated text of the Order rather than from an older note. That matters most where a lender or a purchaser is relying on the position.

Offices are the trap. The retail class in Part 7 is written around display and retail sale and around the provision of financial, professional or other services, and the 2020 Use Classes changes were carried into the Order by reference to those specific sub-paragraphs of Class E rather than to the whole of it. On that reading a pure office in Class E(g) is outside the extension right, even though it now shares a use class with a shop. Occupiers who assume that Class E flexibility carries across into the building rights are often disappointed, and this is a point worth checking against the consolidated Order before design work begins.

The floorspace and height limits

Two words in that table do the heavy lifting. "Original" means the building as it stood on 1 July 1948 or as first built after that date, so every earlier extension, including one built by a previous occupier under the same right, comes off your allowance. "Gross floor space" is measured internally and includes the whole building, not the unit you happen to lease.

The arithmetic is cumulative, and the allowance does not reset when a building changes hands. A 300 m² shop that has already taken a 40 m² lean-to has 10 m² left at best, and probably less once the 25 per cent calculation is run properly. Before taking a lease on the strength of an extension plan, ask the landlord for a planning history and measure the original footprint from the earliest reliable drawing or historic mapping.

Height is measured for the building as extended, not for the extension alone, which catches single-storey shops with a tall parapet.

Boundaries, dwellings and what sits nearby

Separation distances decide more Part 7 cases than floorspace does.

For shops, no part of the development may be within 2 metres of the boundary of the curtilage. For industrial and warehouse premises the figure is 5 metres, and the height allowance drops where the extension sits within a set distance of the boundary. Industrial sites on tight urban plots frequently lose the right on this ground alone.

There are also restrictions keyed to nearby residential use. A Part 7 extension cannot be used as a separate dwelling, and the industrial classes are limited where the premises adjoin a dwelling or where the extension would be within a stated distance of one. The policy intent is plain enough: the right exists to let businesses grow on their own land, not to push plant and loading closer to people's windows.

Parking matters in a less obvious way. Several classes are not permitted where the development would reduce the space available for the parking or turning of vehicles on the site. A yard extension that eats the turning circle can fail even when the floorspace maths works, so plot the swept path before relying on the right.

Article 2(3) land, listed buildings and other exclusions

Several gateways sit outside the numbers.

• Article 2(3) land, meaning conservation areas, National Parks, the Broads, National Landscapes and World Heritage Sites, removes or restricts a number of these rights.
• Development within the curtilage of a listed building is excluded, and listed building consent would be needed in any event.
• A scheduled monument on or adjoining the site removes the right.
• An Article 4 direction made by the council can withdraw the class for a defined area, which is common in town centres with design codes.
• A condition on an earlier permission can remove permitted development rights for the site, which is why the planning history is the first document to read, not the last.
• Where an environmental impact assessment would be required, the right falls away and a full application is needed.

Check the council's local plan proposals map and its list of Article 4 directions, and look at the planning history for every permission on the site rather than only the most recent one.

Hard surfaces, plant and the related classes

The classes that sit alongside the extension rights are the ones most often used in practice and least often checked.

Hard surfaces for the purposes of the undertaking are permitted within the curtilage, subject to limits and to a requirement about surface water where the area is large. The domestic equivalent is a familiar comparison: the rules on front garden paving and permeable surfaces follow the same logic of controlling run-off rather than appearance.

Plant and machinery on industrial land is permitted within limits on height and position, and this is where extraction equipment, chillers and dust plant usually sit. The right covers the installation. It does not neutralise the noise and odour consequences, and a council can still act under statutory nuisance powers. Where a kitchen or food process is involved, a ventilation and extraction statement is worth preparing even when no application is needed, because it is the document the environmental health officer will ask for first.

Enclosures, trolley stores, bicycle stores and waste enclosures are dealt with by their own limits on size and position. Many are small enough to fall within a class, and many fail because they sit forward of the building line or within the boundary separation distance.

Where a change of use defeats the right

Part 7 rights attach to the building's current lawful use. Change the use and the right changes with it, sometimes to nothing.

Three sequences cause trouble. A shop that becomes a hot food takeaway moves into sui generis and leaves the retail class behind. A warehouse that becomes a trade counter operation may move into Class E and lose the generous industrial allowance. And an office or shop that goes residential under the prior approval route takes the building out of Part 7 altogether, which is one of several reasons to settle the long-term use before extending. The sequencing points around Class MA vacancy and continuous use conditions are a good illustration of how a change of use reshapes what is possible afterwards.

The reverse sequence is also worth planning. Extending first under the industrial class and changing use afterwards is lawful, but the council may look at the combination as a single scheme if the two steps are close together and the extension is plainly designed for the later use.

Deciding whether to rely on the right

A prior approval application is not required for these extension classes, so there is no council stamp confirming your reading. That silence is a risk at sale or refinancing.

1. Pull the full planning history for the site, including conditions on every permission.
2. Establish the original building and measure its gross floor space from the best available drawing.
3. Subtract every previous extension, whoever built it.
4. Check Article 2(3) land, Article 4 directions, listed status and scheduled monuments.
5. Check the boundary separation, height and parking or turning limits against the current text of the Order.
6. Where the margin is thin or the value at stake is high, apply for a lawful development certificate for proposed use or development under section 192 of the Town and Country Planning Act 1990. It is the only formal confirmation that works are lawful without permission.
7. Keep the measurements, drawings and dated screenshots of the datasets you relied on.

Where the answer is that a full application is needed, a short planning statement explaining the business need, the floorspace and the amenity effects usually carries a modest commercial extension on its own.

Check which reports a commercial extension needs by browsing the report categories and starting a draft.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.