What Can an Architect Do With an Empty Industrial Unit?
You Have 70,000 Square Feet Standing Empty. Here's What an Architect Can Do About It.
A large vacant industrial unit with retail or leisure planning restrictions might look like a problem. To a chartered architect, it looks like an opportunity — if you understand how to read the building, the planning constraints, and the market.
Here’s the scenario:
You're a property developer or a property management agent. You have a large industrial unit — let's say 70,000 square feet — sitting vacant. It might be on a retail park, an edge-of-town site, or a unit that was previously occupied by a distribution or manufacturing business that has since moved on.
The planning constraints say it can only be used for retail or leisure. That rules out straightforward industrial re-letting. And now the clock is ticking on an empty building that costs money to hold.
This is exactly the kind of brief that Dennis Hellyar Architects works with regularly. Commercial clients — developers, agents, landlords — bring us vacant or underperforming properties and ask a fundamental question: what can this building actually become?
Below, we walk through what a professional architect can realistically offer you at every stage of that process.
A 70,000 sq ft single-storey industrial unit. Previously used for warehousing. Planning restriction: Class E (commercial, business and service) or Sui Generis leisure use only — retail or leisure purposes. The building sits on a 4-acre site with generous car parking. Roof apex is approximately 6 metres at the ridge.
The client: a property management company holding the asset on behalf of an investor. The unit has been vacant for 14 months. Rates relief is due to expire. They need a credible plan.
Step One: Understanding What the Planning Restriction Actually Means
The first thing a property developer or agent often gets wrong is assuming that a planning restriction is a fixed wall. It isn't always. It's a starting point for a professional assessment.
In Wales, permitted use categories are governed by the Town and Country Planning (Use Classes) Order 1987 as amended. A restriction to retail or leisure typically means the building falls within Class E (or parts of it) and potentially Sui Generis uses for certain leisure categories. But the precise wording of the original planning consent or any subsequent condition matters enormously.
An architect working with a planning consultant will:
Review the original planning permission and any conditions attached to it
Assess whether any permitted development rights allow a material change of use within the retail/leisure category without a fresh application
Identify the appetite of the local planning authority for a formal variation or new application if needed
Advise on which leisure or retail uses best fit both the planning context and the building's physical characteristics
In short: a planning restriction tells you the direction of travel, not the destination. An architect helps you work out what's actually achievable within that direction.
Step Two: Reading the Building Honestly
This is where the real value of a measured, experienced architect becomes apparent. Not every building is suitable for every use, and the worst thing a developer can do is pursue a tenant or use that the building physically cannot support.
For a 70,000 sq ft former industrial unit, the critical questions are:
Roof height
This is the single most consequential constraint for leisure uses. A 6-metre ridge height sounds substantial — but it creates immediate problems for several popular leisure categories.
Height clearance requirements for common leisure uses:
Padel tennis: Minimum 6 metres internal clearance recommended, ideally 7 metres or more. At 6 metres to the ridge in a pitched roof, internal height may fall below this once structure and insulation are accounted for.
Indoor tennis: The Lawn Tennis Association specifies 7 metres minimum clear internal height for full-size courts.
Five-a-side football / futsal: Typically requires 5–6 metres clear height — potentially viable depending on the roof profile.
Badminton / pickleball: Badminton requires 9 metres internationally, though recreational play is possible at lower heights. Pickleball courts need approximately 6 metres clear.
Indoor climbing: A bouldering wall can work at 4–5 metres; rope climbing requires 12 metres or more.
Trampoline parks: Generally require 7–8 metres clear height.
A skilled architect doesn't simply flag this as a problem and move on. They model the roof geometry against the floor plan, calculate internal clear heights at different points across the building, and work out what the constraints mean for each potential use. In a large industrial unit, the roof profile is rarely uniform — and some areas of the building may offer better height than others.
What this means in practice: In a 70,000 sq ft unit with a 6-metre ridge height, padel and tennis courts may be achievable in specific areas if the roof structure can be partially raised or if the peak of the roof falls across the courts — but this requires a thorough structural and geometric assessment. It's not a binary yes or no.
Structural condition and floor loading
Retail and leisure uses have very different floor loading requirements to industrial use. A gym with heavy equipment, a soft play facility, or a leisure operator with specialist flooring needs a structural survey to confirm the existing slab can carry the load. An architect commissions and interprets this survey as part of the feasibility process.
Fire strategy and means of escape
A large open industrial shell needs a completely different fire strategy when it becomes a space occupied by the public, especially in high-occupancy leisure scenarios. This affects everything from internal layout to the number and position of exits, and it influences what configurations are actually buildable.
Services and utilities
Former industrial units often have heavy three-phase electrical supplies but limited gas, inadequate welfare facilities, and drainage that was designed for industrial processes rather than public use. An architect assesses the gap between what's there and what each potential use demands — and gives you a realistic cost to bridge it.
Step Three: Developing a Credible Use Strategy
Once the building is properly understood, the architect can help develop a use strategy that's grounded in what's actually achievable — rather than what looks good on a brochure.
For a 70,000 sq ft unit with retail/leisure restrictions and a 6-metre roof, realistic and commercially viable uses to explore include:
Gym and fitness
Large-format fitness operators (Pure Gym, JD Gyms, The Gym Group) actively seek units of this scale. Floor loading and roof height are generally not limiting factors. High footfall, strong covenant.
Tenpin bowling / entertainment
Operators such as Hollywood Bowl require large footprints and benefit from lower ceiling heights. A 6-metre roof is workable. Often combined with food and beverage to increase dwell time.
Discount / value retail
B&M, Home Bargains, The Range and similar operators regularly take 20,000–40,000 sq ft. A 70,000 sq ft unit may suit a single anchor or a multi-let retail configuration with smaller units created internally.
Soft play / children's leisure
Large-format indoor play facilities work well in former industrial units. Relatively low fit-out ceiling requirements. Growing market in South Wales with limited quality supply.
Padel + multi-sport (with conditions)
Padel's explosive growth makes it attractive, but the roof height requires careful assessment. Viable if internal clear height is sufficient in the right areas of the building — or if a partial roof raise is economically justified.
Food and beverage anchor
Restaurant pods or a food hall concept within part of the unit can complement an adjacent leisure operator and drive combined footfall. Requires significant services upgrade but is increasingly popular with developers.
Multi-let vs. single occupier: A building this size doesn't have to be a single let. An architect can design a subdivision strategy that creates multiple smaller units within the shell — allowing you to spread risk across several tenants at different lease lengths, while retaining flexibility to recombine if a single large occupier emerges. This is a common and effective strategy for units over 50,000 sq ft with planning restrictions that limit the occupier pool.
The Roof Height Question: What Are the Options?
Let's deal with this directly, because it's often the deciding factor for the most commercially attractive leisure uses — padel, tennis, and similar sports.
If the existing roof sits at 6 metres and you need 7 metres of internal clear height, there are four realistic responses:
Rule out height-sensitive uses and pursue alternatives. Straightforward, lowest cost, fastest. The building becomes a gym, a soft play centre, or a retail occupier. You don't spend money solving a problem you don't have to solve.
Partial roof raise over specific courts. In some structural configurations, it is possible to raise a section of the roof over a defined area of the building — enough for four to six padel courts, for example — while leaving the surrounding area at existing height. An architect and structural engineer will assess whether the existing frame can accommodate this and at what cost.
Full roof replacement to a greater height. Possible but expensive. Rarely justified unless the building's value uplift clearly outweighs the capital cost, or unless you have a pre-let in hand with an operator who requires it.
Re-examine the height data. Industrial units are often measured to the apex of a pitched roof, but padel courts require clearance above the court area — which may be at a lower point on the pitch. A detailed measured survey sometimes reveals that the internal clear height is better than the apex measurement suggests, or that positioning courts along the centreline of the building solves the problem without any structural intervention.
"The roof height problem is real, but it is almost never binary. The architect's job is to find out exactly what the numbers are — and then explore what's possible."
This is a case where engaging an architect early — before you've had conversations with operators or committed to a use — can save significant time and money. The cost of a measured survey and a preliminary feasibility assessment is modest compared to the cost of pursuing the wrong use for six months.
What Happens After Feasibility?
Once there's a preferred use or a shortlist of viable options, an architect can move into the formal stages of developing the scheme:
Pre-application engagement with the local planning authority
Before submitting any application, a pre-application discussion helps establish the LPA's likely position on the proposed change of use, any design conditions they'd want to see met, and whether there are any material planning considerations specific to the site.
Planning application (if required)
If the proposed use requires a formal change of use application — or if any structural alterations to the building require full planning — the architect prepares and submits the application, including design and access statements, drawings, and any supporting reports.
Building Regulations
Converting a former industrial building for public occupation always requires Building Regulations approval. This covers fire safety, means of escape, structural changes, energy performance, accessibility (Part M), and ventilation. The architect coordinates the technical package and works with the BCB (Building Control Body) through the process.
Technical design and fit-out drawings
For the fit-out itself — whether you're doing it speculatively to attract a tenant, or designing to a specific operator's brief — the architect produces the technical drawings that contractors price and build from.
Tendering and contract administration
Where appropriate, the architect can manage the tender process, appoint a contractor, and administer the building contract through to practical completion. This protects the client's interests and provides an independent check on quality and programme.
What Does This Look Like for a Property Manager?
If you're a property management agent rather than a developer — holding an asset on behalf of an investor client — your brief is slightly different. You need to demonstrate to your client that you have a credible plan to re-let the building, and you need to be able to quantify the capital expenditure required before you can establish a rental expectation.
An architect can provide a structured feasibility report that gives you:
A clear assessment of the building's physical suitability for each use category
A range of use options ranked by planning deliverability, market demand, and capital cost
A high-level cost estimate for each option (prepared with a quantity surveyor where appropriate)
A programme estimate — how long from instruction to practical completion for each route
A recommendation on whether to proceed speculatively or pursue a pre-let before committing to fit-out expenditure
That report becomes the document you take to your investor client — or to prospective occupiers — to demonstrate that the asset has a realistic future.
The Value of Local Knowledge
In South Wales specifically, understanding the planning framework matters. Wales operates under its own planning policy system — Planning Policy Wales and associated Technical Advice Notes — which differs in important respects from the English system. Local planning authorities across the region, from Cardiff Council to the Vale of Glamorgan, have their own retail and leisure policies that reflect their local development plans.
Dennis Hellyar Architects has worked on commercial projects across Cardiff, the Vale of Glamorgan, and the wider South Wales area, and has an established understanding of how local planning authorities approach commercial change-of-use applications. That knowledge matters when you're trying to get a scheme through planning efficiently.
Frequently Asked Questions
Do we need planning permission to change the use from industrial to retail or leisure if the planning restriction already allows it?
Not necessarily. If the building already has an extant planning consent or condition restricting it to retail or leisure, and you're proposing a use that falls within those categories, you may not need a formal change of use application. However, any structural alterations — including roof modifications or the creation of new mezzanines — will typically require both planning permission and Building Regulations approval. An architect and planning consultant should review the specific consent documents before you proceed.
How long does it take to get a 70,000 sq ft unit from vacant to operational for a leisure use?
From initial feasibility to practical completion of a fit-out, a project of this scale typically takes 18 to 30 months. Planning (if required) alone can take 3 to 6 months. A pre-application process, where you engage the LPA before formal submission, can reduce uncertainty and improve the quality of the eventual consent. The programme depends heavily on whether you're fitting out speculatively or to a tenant's specific brief.
Is padel tennis viable in a building with a 6-metre roof?
It depends on the internal clear height rather than the apex measurement, and on where in the building the courts are positioned. A measured survey is essential before drawing any conclusions. In some buildings with 6-metre apexes, court positioning under the ridge makes padel workable without structural intervention. In others, a partial roof raise over the court area is needed. This is a question of engineering and geometry, not a simple yes or no.
What's the difference between a planning restriction and a planning condition?
A planning restriction can refer either to a condition attached to a specific planning permission, or to the general use class designation applied to a site or building. The implications are different: a use class restriction defines what categories of use are generally permissible, while a planning condition attached to a consent may be more specific and binding. Understanding which applies — and whether there's scope to vary it — requires a review of the original consent documentation by a qualified professional.
Can we subdivide the unit to attract multiple smaller tenants?
In most cases, yes — subject to planning and Building Regulations. A subdivision strategy can make a building of this size significantly more lettable by reducing the commitment required from any single occupier. An architect designs the subdivision in a way that preserves flexibility, meets fire safety requirements for each unit, provides independent access and servicing, and allows the units to be recombined if required.
Talk to Us About Your Commercial Property
If you have a vacant industrial or commercial unit in South Wales that you need to unlock, we're happy to have an initial conversation about what's possible. No obligation, no jargon.
