Building self-service storage in Greater London is a different exercise from building it anywhere else in the country, and the funding has to reflect that. Land is scarce and priced accordingly, single-storey sites are largely unavailable at sensible values, and the schemes that get consented and built are conversions of existing buildings or multi-storey developments that go up rather than out.
That changes the cost base, it changes where the money goes within a scheme, and it changes what a lender is monitoring as the facility draws down. We arrange self-service storage development finance across the UK, and this guide covers the London version of it specifically: what the facility funds, how the two ceilings work, why conversion usually wins in the capital, and how the whole thing exits. Figures are indicative market commentary, not quotes or offers.
What a development facility covers on a storage scheme
Self-service storage development financing is a short-term facility that funds construction of a new storage facility or conversion of an existing building, released in stages as works progress rather than as a single advance. Loans run from around £500,000 to £50m and beyond.
The part that distinguishes it from ordinary commercial development finance is the fit-out. On most development schemes, the building is the product. On a storage scheme, the building is a shell that produces no income at all until it is racked, partitioned, secured, lit, alarmed and fitted with access control. The racking and partitioning that turn open floorspace into lettable storage units are what create the revenue, and they have to be inside the facility.
We flag this because sponsors coming from residential or industrial development routinely size their first storage facility against the build cost and then discover the fit-out sitting outside the loan. A lender that understands the sector will fund it. A generalist lender will not, and that difference is worth more than a few basis points on the rate.
The two ceilings: loan to cost and loan to gross development value
A storage development facility is sized against two tests simultaneously, and takes whichever produces the lower number.
The first is loan to cost, up to around 65 to 75% of total project cost including land, build and fit-out. The second is loan to gross development value, up to around 60 to 65% of the appraised value of the finished store. The developer funds the balance in equity.
Which one binds tells you something useful about the scheme. If loan to cost binds, the scheme is expensive relative to what it will be worth, which in London usually means the land was bought keenly rather than cheaply. If loan to GDV binds, the appraisal is doing a lot of work and the lender is signalling that it does not fully believe the projected stabilised trading income the GDV is built on.
That second point deserves attention, because the GDV of a self-service storage scheme is not a comparable-based number. It is the capitalised value of an operating business that does not exist yet, built from projected occupancy, projected achieved rate and a projected stabilisation date. The evidence base for those projections is what a credible appraisal stands on. Prime London and South East weighted trading stock values at £458 per sq ft on a 5.0% net initial yield (Big Yellow FY2026 results, JLL-valued), which is the top of the UK range and the reason London schemes appraise strongly, but a lender will still test whether your specific catchment supports prime assumptions.
Where the gap between the lender’s advance and the equity you want to commit is too wide, mezzanine finance can top the stack to around 85 to 90% of cost from around 12%, or an equity partner can take the gap in exchange for a profit share. Both are covered in other guides in this series.
Why conversion beats ground-up in the capital
Our planning dataset holds 99 self storage applications across 49 local planning authorities, and Ealing is the single most active authority in it with seven applications (Construction Capital planning data, August 2026). Roughly half of all applications in the dataset explicitly cite use class B8, storage and distribution, which is the planning route conversions take.
That is the London pattern in miniature. Where land is expensive, you buy a building that already exists, usually an industrial or retail unit with the right use class or a realistic path to it, and you convert it. You avoid groundworks, you avoid most of the structure, and you shorten the programme substantially, which on a facility charging from around 8% with interest rolling is worth real money.
Construction costs bear this out. Core build plus fit-out runs at £550 to £850 per sq m excluding land and professional fees, with single-storey at £550 to £700 and multi-storey at £700 to £850 (PSL Limited, UK Self Storage Construction Costs, February 2026). A conversion starts from an existing envelope, so a much larger share of that spend is fit-out rather than structure.
The London caveats are real, though. Conversion carries planning risk if the use class does not already fit, and the prior approval route under Class R appears only four times in our whole dataset, so the agricultural-to-storage permitted development path is marginal rather than a strategy. Existing buildings also carry surprises: floor loadings that will not take racking at the density you modelled, inadequate power, fire strategy work on a multi-storey conversion, and access constraints that limit the vehicle sizes your customers can bring. Budget contingency for the building you cannot fully survey until you own it.
What fit-out costs, and why it is most of the spend
On a conversion, expect fit-out to dominate the construction budget. The elements are racking and partitioning systems, doors and locks, access control and CCTV, fire detection and suppression, lighting, power distribution, lift provision on a multi-storey scheme, and the reception and retail area that sells packaging and takes enquiries.
Two things follow for the funding. First, fit-out can be phased. You do not have to fit out every floor before you open, and phasing lets you match capital deployment to actual demand, which shortens the period you are paying development-facility rates on money you are not yet earning against. Lenders are generally comfortable with phased fit-out where the first phase is sized to reach a credible opening occupancy.
Second, fit-out is what the monitoring surveyor is checking on a storage drawdown, and it does not behave like structural progress. Racking arrives and is installed quickly, so drawdowns can be lumpier than on a conventional build. Agree the drawdown schedule against the actual procurement programme rather than a standard monthly profile, or you will find yourself funding a large racking order out of equity while waiting for the next certified draw.
Staged drawdowns and rolled interest, in practice
The facility is drawn in stages against certified works, and interest is rolled into the loan rather than serviced monthly, because a site under construction generates no income to service anything from.
That has a compounding consequence people underestimate. A headline rate from around 8% on a facility that runs 12 to 36 months with interest rolling means the total accrued cost at exit is materially above what the headline suggests. We model the total cost over the term rather than comparing headline rates, and we advise every sponsor to do the same when they compare offers. A slightly higher rate on a facility with a faster drawdown profile and no exit fee can cost less in cash than a keener headline with a heavy fee structure.
Add the arrangement fee at typically 1 to 2%, monitoring surveyor costs across the term, valuation, and sometimes an exit fee. Those are the numbers that decide which offer is actually cheaper.
Who lends on storage development, and what investors want to see
Self-storage development sits awkwardly for generalist real estate lenders, so it is worth knowing which desks actually write these loans.
Specialist property lenders and debt funds with operational real estate experience are the core of the market. They understand that the fit-out is revenue-generating capital expenditure rather than a cost overrun, and they are comfortable sizing against a gross development value built from projected trading. Challenger banks lend on the sector, generally to operators with a completed scheme behind them. High-street banks appear mainly where the sponsor is an established storage operator with an existing relationship. The self-storage industry has enough of a track record now that appetite among storage operators and their funders is genuinely broad, but the difference between a lender who has funded stores before and one who has not shows up in the terms and in how much of the fit-out sits inside the facility.
Where equity investors are involved, their diligence runs alongside the lender’s and asks different questions. Investors want the catchment work: population within the drive-time, competing self storage facility stock and its achieved rates, and what happens to the projection if a competitor opens during lease-up. They want the trading assumptions evidenced rather than benchmarked against national averages. And they want to know the exit, because their return arrives at the refinance or the sale rather than at practical completion.
The three institutional transactions of the last two years are the reference point for what that exit can look like at scale: Shurgard acquired Lok’nStore for £378m (Lok’nStore RNS, April 2024), CapitaLand agreed just over £1bn for Access Self Storage’s 57 facilities, and QuadReal and Clear Sky bought a 27-asset portfolio inside a £480m joint venture, both in March 2026 (Inside Self Storage and QuadReal, March 2026). Investors reading a single-scheme appraisal are, ultimately, asking whether it could one day be part of something a buyer like that wants.
Where the scheme needs bridging finance to secure the building before the development facility is in place, that is a separate conversation and we cover it in the bridging guide in this series.
The exit is the price of entry
No development lender writes a storage facility without knowing how it gets repaid, and on a storage scheme the exit is more complicated than on a residential build where you sell the units.
Practical completion does not repay a development facility, because the store opens close to empty. The route is a development exit loan: a refinance at practical completion that repays the development facility and carries the store through lease-up at a materially lower rate, typically up to 60 to 70% loan to value from around 6%. Then, once occupancy settles, typically 3 to 5 years after opening, the store refinances again onto a long-term commercial mortgage at the keenest pricing it will see.
The national occupancy figures explain why that middle step exists. All-store occupancy across the UK runs at 74.5% while mature stores average 79.6% (SSA UK / Cushman & Wakefield Annual Industry Report, 2026). That gap is lease-up drag, and a newly opened store sits at the bottom of it. A development lender will want to see that you have a credible exit route and enough term on the facility to reach it, which is why terms run to 36 months rather than stopping at practical completion.
Frequently asked questions
Is converting a building cheaper than building from scratch? Usually, where a suitable building exists. A conversion avoids groundworks and most of the structure, and it shortens the programme, which matters when interest is rolling on a facility priced from around 8%. Construction costs run at £550 to £850 per sq m across formats (PSL Limited, February 2026), and a conversion starts from an existing envelope so more of that is fit-out than structure. The trade-off is planning risk where the use class does not fit, and the constraints of a building you inherit: floor loadings, power, fire strategy and access.
What are self storage development finance rates? Indicatively from around 8%, with an arrangement fee of 1 to 2%, monitoring costs and sometimes an exit fee. Pricing moves with leverage, the strength of the feasibility work and the sponsor’s track record. Because interest is rolled into the facility during the build, compare total accrued cost over the term rather than headline rates.
How long should a development facility run on a storage scheme? Typically 12 to 36 months. Size it against the construction programme plus a realistic buffer to reach the development exit refinance, not just to practical completion. A store that opens on time but cannot refinance for another six months because the exit lender wants to see early occupancy is a facility that needs the term to cover it.
Talk to us about a scheme
If you have a London site or a building to convert and you want to know what it will fund at, send us the appraisal. We will tell you which of the two ceilings binds, whether the fit-out sits inside the facility, and what the exit route realistically looks like. Talk to an experienced broker about a storage scheme.
Self Storage Finance is a trading name of Lenzie Consulting Ltd, registered in England and Wales under company number 08174104, registered office Lynch Farm, Kensworth, Dunstable, LU6 3QZ. We are a finance arranger and introducer, not a lender, and we do not provide financial, legal or tax advice. Most self-storage property finance arranged for corporate and experienced-investor borrowers is unregulated business lending that falls outside the Financial Conduct Authority’s regulated-mortgage perimeter. Some lending, including to individuals or owner-occupiers, can be a regulated mortgage contract; where a transaction would be a regulated mortgage contract or otherwise require FCA authorisation, we refer it to an appropriately authorised firm. Indicative terms, rates and loan-to-value figures are illustrative, vary by lender, asset and borrower, and are not an offer of finance.