Evidencing no net loss of industrial floorspace in a SIL
No net loss in a Strategic Industrial Location is tested against capacity rather than the sheds standing today. How to measure, evidence and present the floorspace case.
If your site sits inside a Strategic Industrial Location, the question an officer asks first is arithmetic. How much industrial floorspace is there now, how much will there be afterwards, and where is the measurement from. The strategic industrial location policy in the adopted London Plan protects these areas for industrial, logistics and related uses, and expects no net loss of industrial floorspace capacity when sites are redeveloped. The policy survives, but the arithmetic is where applications are won.
Our overview of industrial land and no net loss in London covers the policy structure. This note deals with evidencing the floorspace position in a redevelopment application.
What the designation protects
Strategic Industrial Locations are designated in borough local plans within the strategic framework of the London Plan. They are reserved for industrial and related functions, which in use class terms covers general industrial and storage and distribution uses, light industrial uses of an industrial character, and a range of sui generis activities such as waste management, utilities, fleet and logistics operations.
The designation protects a function rather than a set of buildings. That distinction matters when the existing buildings are obsolete, because replacing a 1960s shed with modern floorspace of the same or greater quantum is entirely consistent with the designation, while replacing it with offices or housing is not.
Check which designation you actually have before building an argument. Strategic Industrial Locations, Locally Significant Industrial Sites and non-designated industrial land are governed by different policy, and the scope for mixed use rises as you move down that list. Borough proposals maps and the national planning data service both carry the boundaries.
The no net loss expectation in practice
No net loss is tested against capacity rather than against the floorspace that happens to stand on the site today. Capacity reflects what the site could accommodate for industrial purposes, which on a site with low site cover may be more than the existing building.
| Measurement question | What to settle before you draw anything |
|---|---|
| Basis of measurement | Gross internal or gross external area, used consistently |
| Baseline date | The floorspace at a stated date, with evidence |
| Vacant floorspace | Counted as existing, not written off |
| Mezzanines and ancillary offices | Whether included, and on what basis |
| Recently demolished buildings | Usually counted as existing capacity |
| Yard, service and circulation space | Capacity, not floorspace, but assessed |
Settle the measurement basis with the borough in writing at pre-application stage. An application that measures existing floorspace gross externally and proposed floorspace gross internally will be read as presenting a loss as a gain, whether or not that was the intention.
Intensification and co-location routes
Intensification is the orthodox answer where a site is underused. Multi-storey industrial, taller single-storey units with increased clear height, shared yards, stacked parking and basement servicing all increase floorspace on the same footprint.
The practical constraints are real. Multi-storey industrial needs vehicle access to upper floors by ramp or goods lift, and the floor loadings, column grid and clear heights that logistics occupiers require. A design that technically adds floorspace but cannot be let to an industrial occupier delivers nothing the policy was protecting, and boroughs have become good at spotting it.
Residential co-location is a different matter. Within a Strategic Industrial Location, introducing housing is generally not supported, and the co-location routes in London Plan policy are directed at locally designated and non-designated industrial sites. Where an applicant wants residential on designated land, the honest route is to test the designation itself through the local plan process rather than through an application.
Evidence on existing floorspace
Four strands of evidence make this section of a planning statement defensible.
- A measured survey of the existing buildings, by a surveyor, stating the measurement standard used.
- Historic evidence of floorspace that has been demolished or is unlettable, including rating records, earlier planning permissions and dated aerial imagery.
- A schedule of existing uses by unit, with use class and occupier type, to establish the industrial character of the baseline.
- A capacity assessment showing what the site could accommodate under a policy-compliant industrial scheme, used as the comparator.
Point four is the one applicants resist and officers rely on. Where the site cover is low, the borough will compare your proposal against a notional intensified industrial scheme rather than against the sheds standing today. Produce that comparator yourself, with your assumptions stated, instead of letting the authority build one.
Relocating existing occupiers
Redevelopment displaces businesses, and the planning process now asks what happens to them. Expect a relocation strategy where occupiers are in place: who they are by sector and size, what floorspace and yard they need, what has been offered, and what the phasing allows.
Phasing is the strongest answer. A scheme that builds new units on part of the site, moves occupiers across, then redevelops the remainder, keeps businesses in the borough and takes most of the heat out of the objection. It costs programme time. It also removes a reason for refusal, and obligations securing relocation assistance or marketing of new units to displaced occupiers often appear in the section 106 agreement.
Where the designation will not bend
Three positions are close to fixed, and knowing them saves months of abortive work.
Housing within a Strategic Industrial Location is not supported by the policy, whatever the viability case. A net reduction in industrial floorspace capacity without replacement elsewhere will be resisted. And a scheme that converts industrial floorspace to office or light industrial of a non-industrial character, in a building no logistics occupier could use, will be treated as a loss even where the floorspace figure holds.
What is negotiable is the mix of industrial uses, the building typology, the phasing, and the treatment of boundaries where the designation adjoins housing. Those are the arguments worth having. The same policy discipline appears in schemes within opportunity areas, where several strategic designations can apply to one site, and in design-led capacity work of the kind described in our note on optimising site capacity.
Writing the floorspace case
Put the numbers in the first two pages of the planning statement, in a single table, with the measurement basis named and the source of each figure cited. Existing floorspace, proposed floorspace, the difference, and the capacity comparator. Then explain the industrial quality of what is proposed: clear heights, floor loadings, yard depths, service access and the occupier types the design suits.
The London Plan is kept under review and a replacement plan changes policy numbering and sometimes substance, so check which version is adopted at the time you submit and cite it by edition. Section 38(6) of the Planning and Compulsory Purchase Act 2004 still requires determination in accordance with the development plan unless material considerations indicate otherwise, and in London that plan includes the London Plan alongside the borough's own.
To see which supporting documents an industrial redevelopment is likely to need, enter the site postcode on PlanScope and work through the guided questions.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. This is general guidance, not legal advice; check the position with the borough or a qualified professional before relying on it.
Frequently asked questions
What does no net loss actually measure?
Industrial floorspace capacity rather than the floorspace standing today. On a site with low site cover, the borough will compare your proposal against a notional intensified industrial scheme. Settle the measurement basis, gross internal or gross external, and the baseline date in writing at pre-application stage.
Does vacant floorspace count in the baseline?
Yes. Vacant and unlettable floorspace is normally counted as existing, and recently demolished buildings are usually treated as existing capacity. Support the position with rating records, earlier permissions and dated aerial imagery rather than relying on the current occupancy schedule alone.
Can housing be built in a Strategic Industrial Location?
Generally not. The co-location routes in London Plan policy are directed at locally designated and non-designated industrial sites. Where an applicant believes designated land should come forward for housing, the route is to test the designation through the local plan process rather than through a planning application.
Is multi-storey industrial a reliable answer?
Only where it is lettable. Upper floors need vehicle access by ramp or goods lift, and the floor loadings, column grid and clear heights that logistics occupiers require. A design that adds floorspace no industrial occupier can use delivers nothing the policy protects, and boroughs identify it quickly.
What should a relocation strategy contain?
The existing occupiers by sector and size, the floorspace and yard each needs, what has been offered to them, and how the phasing accommodates the moves. Phased redevelopment that builds new units first and moves occupiers across is the strongest answer, and obligations securing it often appear in the agreement.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.