Office to Residential Conversion Finance in the City of London
How developers turn surplus office stock into homes in the Square Mile: the Class MA permitted development route, the real cost of a conversion, how lenders appraise the deal, and how development finance, bridging and JV equity fund the gap.
Office to residential conversion finance is specialist commercial property funding that a lender or equity partner provides to a developer converting a commercial office building into residential dwellings, structured around the planning route, the works, and the completed gross development value rather than the building's existing use. In the City of London, where surplus office stock sits alongside some of the most valuable residential land in the country, converting commercial property to homes has become one of the most active development plays in the Square Mile. This guide explains how the finance works, how lenders appraise a conversion, and how developers combine development finance, bridging finance and equity to fund the gap.
A conversion is not a ground-up build and it is not a light refurbishment either. It sits in between: you are taking an existing commercial asset, changing its use, and delivering finished residential property. That middle position is exactly why conversion finance is its own discipline, and why the lenders who fund it price the deal on the works and the exit, not on the office you started with.
Class MA and the permitted development route
Most office to residential conversions in England now run under Class MA of the permitted development rights, which since 2021 allows commercial, business and service premises to change use to residential without a full planning application. Class MA is a prior approval process, not full planning permission: you apply to the local planning authority for prior approval on a defined list of matters (flooding, contamination, noise, natural light, and the impact of losing commercial floorspace), and if the authority does not refuse within the statutory period, the change of use is permitted.
The distinction matters for finance because prior approval carries less planning risk than a full application, but it is not risk free. There are limits: the building must have been in qualifying commercial use for a continuous period, the conversion is subject to floorspace thresholds, and every new dwelling must meet the nationally described space standards. Listed buildings are excluded, and, critically for central London, land inside a conservation area can lose permitted development rights where an Article 4 direction is in place. A developer buying an office on the assumption that Class MA applies, without checking those exclusions, is taking a risk a lender will price for.
Why the City of London is a special case
The City of London Corporation is its own planning authority, and the Square Mile is unlike any other market for a conversion. Roughly 55 per cent of the City is covered by conservation areas (Historic England and local authority data), and the Corporation has historically protected commercial floorspace to preserve the district's role as a financial centre. Article 4 directions removing Class MA rights apply across large parts of the City, which means many office to residential conversions here need full planning permission rather than the permitted development route, and the Corporation weighs the loss of office space carefully.
That does not make conversion impossible: it makes it a scheme that lenders assess on the strength of the planning position. Where full planning is required, the City's 72 per cent planning approval rate (City of London Planning Committee Reports 2024/25) is the number lenders watch, alongside heritage constraints and the St Paul's Heights sightlines that shape what can be built. Older, lower-grade office stock on the fringes of the City, around Aldgate, Smithfield and Farringdon, is where much of the practical conversion activity sits, and where the residential values that support a fundable exit are strongest.
The real cost of converting commercial property
The single biggest mistake on a conversion is treating it like a refurbishment. Converting a commercial office to residential use is a heavy build. Office floorplates are deep, so achieving compliant natural light and outlook for every habitable room often means carving in lightwells or setting back the massing. Commercial buildings run their services centrally; a residential scheme needs individual metering, new soil stacks, acoustic separation between dwellings, and a fire strategy built for sleeping accommodation rather than daytime occupation.
Facade retention is common in the City, where a conservation area or the building's contribution to the streetscape means the exterior stays while the interior is stripped back to frame. That is expensive and slow, and it drives up both the build cost and the finance cost, because interest rolls up across a longer programme. Add the cost of meeting the space standards, the minimum energy efficiency standards on any retained commercial element, and the professional fees for a scheme with real technical complexity, and the works budget on a City conversion is closer to a new build than to a coat of paint. The lender's monitoring surveyor will test that budget hard.
How lenders appraise a conversion
A conversion sits between two valuations, and understanding both is the key to the finance. On day one the building has an existing use value: what the office is worth as a commercial asset, whether that is vacant possession value or an investment value with income. On completion it has a gross development value, or GDV: the aggregate value of the finished residential units. The scheme only works if the GDV, less the purchase price and the works, leaves a developer's profit that justifies the risk.
Development finance for a conversion is sized off two ratios. Loan to cost measures the facility against total project cost, including the purchase, the works, fees and finance; a senior conversion facility typically runs to 65 to 70 per cent of cost. Loan to GDV caps the facility against the finished value, usually around 65 per cent. Your facility is limited by whichever ratio bites first. The gap between what the senior lender advances and the total cost is the equity the developer must find, and closing that gap is where the funding structure is really decided. A clean planning position, whether a granted prior approval or a full consent, widens the lender panel and sharpens the terms, because it removes the biggest single unknown from the appraisal.
The valuation itself does a lot of work on a conversion. A lender instructs a valuation of the completed residential property to set the GDV, and often a second valuation of the commercial building in its existing use to confirm the day-one security. Because a conversion changes a commercial asset into residential property, the two figures can be far apart, and the whole appraisal turns on the valuer's view of the finished units in that location. In the City, where residential values run to £1,400 per square foot (HM Land Registry Price Paid Data 2025), a well-located conversion project can support a GDV that carries the works and the finance costs comfortably, which is exactly why the numbers stack up here when they would not elsewhere.
Funding structures: development finance, bridging and equity
There are three building blocks in a City conversion, and most deals use more than one. Senior conversion development finance is the foundation: a first charge facility, drawn in stages against the works as a monitoring surveyor certifies progress, with interest rolled up and repaid at exit. It is the cheapest money in the stack and it funds the bulk of the build.
Bridging finance does a different job. A conversion bridging loan, or a bridge to convert, is short-term money used to buy the office quickly, often before prior approval is confirmed or while a full planning application is running, and it is drawn as a lump sum rather than in stages. Developers use a bridging loan to secure the building, then refinance onto conversion development finance once the planning position and the works package are ready. Bridging finance is more expensive per month than development finance, so it earns its place by winning the site, not by funding the build.
Equity closes what debt will not. Where senior debt and bridging leave a shortfall, or where a developer wants to preserve cash across several schemes, a joint venture equity partner funds the balance in return for a share of the profit. Equity is the layer that can carry prior-approval risk on a Class MA scheme, or planning risk on a full application, because the partner takes development risk alongside the developer rather than lending against a settled consent. This is the gap that equity funding for London conversion schemes is built to close, funding the deposit and shared costs that a senior lender will not reach in exchange for a profit share rather than a track record. On a City conversion, where the works are heavy and the planning position can be finely balanced, the equity layer is often what makes the deal fundable at all.
Exit routes: unit sales or a block sale
A lender funds the exit as much as the build, so the exit strategy has to be evidenced before anyone commits. Most City conversions exit one of two ways. The first is individual unit sales: the finished apartments are sold on the open market, and the sales proceeds repay the development finance. Where sales run slower than the programme, development exit finance, a lower-cost bridge against completed and unsold units, buys time to sell without the original facility expiring.
The second is a single block sale to an institutional buyer or a build to rent operator, who takes the whole scheme as an income-producing residential asset. A block sale is a cleaner, faster exit that removes sales risk, but it usually prices below the aggregate of individual sales, so the appraisal has to work at the block value. A third route is to hold: a developer who wants to keep the finished apartments refinances the development finance onto a term mortgage, usually a buy-to-let mortgage on the residential units or a commercial mortgage where part of the scheme stays commercial, and lets the property produce rental income. Which exit a lender underwrites shapes the whole facility, and a credible, evidenced exit is the difference between competitive terms and no terms at all.
Why use a specialist conversion finance broker
Office to residential conversion finance is not a single product you choose off a shelf; it is a stack of facilities that has to be assembled to fit the building, the planning route and the exit. A specialist commercial property finance broker earns their place by knowing which lenders are genuinely comfortable funding a City conversion, which will take a Class MA prior approval and which insist on full planning, and which price the works realistically rather than as if the office needed a light refurbishment. Securing the right terms is as much about matching the scheme to the lender as it is about the headline rate.
Choosing between debt, bridging and equity is where a broker adds the most value. On a heavy conversion project the cheapest facility on paper is rarely the best solution once the works programme, the valuation and the exit are modelled in full. We arrange the senior development finance, layer in a conversion bridging loan to win the building, and structure the equity that carries the planning and delivery risk, so the developer takes the funding solution that actually completes the project rather than the one that looks cheapest at term sheet stage. As changes to permitted development rights and City planning policy shift what is possible, having a broker who tracks those changes keeps a conversion project fundable.
Commercial property finance for a conversion is a specialist market, and the costs, the covenants and the valuation requirements differ from lender to lender. Some elements of a commercial mortgage are unregulated, and this guide is general information about how conversion finance works rather than financial advice or an offer of finance; the Financial Conduct Authority regulates certain lending, and the right structure for any given conversion project depends on the specifics of the scheme, the borrower and the exit.
Every conversion has its own challenges, and the due diligence a lender runs reflects that. Beyond the valuation and the planning check, expect scrutiny of the works package, the professional team's record on similar residential conversions, ground and structural surveys, and the considerations specific to an older commercial building: asbestos, existing services, and the condition of any retained facade. Well-run conversion projects budget for this diligence and the associated costs up front, because a surprise mid-build is far more expensive than finding it early. It is also where a commercial property broker who has funded comparable projects saves a developer time, steering the scheme past the problems that stall other applications and keeping the mortgage or refinance exit on track.
A worked example
Take a tired 12,000 square foot office building on the fringe of the City with the benefit of prior approval under Class MA for conversion to eight apartments. The purchase price is £4.2 million. The conversion works, including facade retention, new services, lightwells and the professional team, come in at £2.4 million, with fees and finance taking total project cost to around £7.4 million. At City residential values, the finished scheme has a gross development value of roughly £9.6 million.
A senior lender advances 65 per cent of GDV, about £6.2 million, but caps the same facility at 70 per cent of cost. The developer needs to find the balance of roughly £1.2 million plus contingency. A conversion bridging loan buys the building at pace, is refinanced onto the senior development facility once works begin, and a joint venture equity partner funds most of the remaining gap in return for an agreed profit share. The developer contributes a modest slice of cash and the delivery expertise, and the scheme that would have been unfundable on debt alone gets built. The numbers here are illustrative, not a quote, but the shape is typical of how a City conversion is funded.
The City of London conversion picture
The Square Mile is a demanding place to convert, but the residential values and the depth of surplus office stock are why the numbers work. These figures set the context lenders price against.
City of London residential values are among the highest in the country, supporting fundable GDVs on well-located office conversions.
Most applications to the City of London Corporation are approved, though heritage and floorspace-protection policies shape what gets consent.
More than half the Square Mile sits in a conservation area, where Article 4 directions often remove Class MA permitted development rights.
A steady pipeline of live schemes across the City, with older fringe office stock the main source of conversion opportunities.
Office to residential conversion finance FAQs
Can I get conversion finance without planning permission in place?
Sometimes, but on tighter terms. A conversion bridging loan can be arranged to buy an office before prior approval or full planning is confirmed, priced for the added planning risk. Most development finance lenders, though, want the planning position settled, a granted Class MA prior approval or a full consent, before they will fund the works. The cleaner the planning, the wider the lender panel and the keener the rate.
What is the difference between a conversion bridging loan and development finance?
A conversion bridging loan is short-term money drawn as a lump sum to buy the building quickly. Conversion development finance is drawn in stages against the works as a monitoring surveyor certifies progress, and it funds the build itself. Many City conversions use both: bridging to secure the site, then development finance for the conversion, refinanced once the planning and works package is ready.
Does the City of London allow office to residential conversion under permitted development?
In parts, but Article 4 directions across much of the City remove Class MA permitted development rights, so many conversions here need full planning permission rather than the prior approval route. The Corporation also protects commercial floorspace. A developer should check the specific building's planning position, including any conservation area and Article 4 constraints, before assuming permitted development applies.
How much deposit or equity does a conversion need?
On a senior facility capped around 65 to 70 per cent of cost, expect to contribute at least 30 to 35 per cent of total project cost, before contingency. Mezzanine finance can trim the cash requirement, and a joint venture equity partner can fund most of the balance in return for a profit share, which is how many developers reach a workable deal on a heavy City conversion.
Do I need conversion experience to get finance?
It helps but it is not essential. Lenders and equity partners want to see a credible scheme, a costed works package, an experienced professional team and a realistic exit. A first-time converter can still get funded by surrounding the deal with delivery expertise and, where the numbers demand it, an equity partner who lends experience as well as capital.
Data sources: HM Land Registry Price Paid Data 2025 (residential values); City of London Planning Committee Reports 2024/25 (planning approval rate); Historic England and local authority data (conservation coverage). Figures are typical ranges for illustration and not a quote or an offer of finance.
Funding a City of London conversion?
Tell us about the building, the planning position and the works, and we will tell you which combination of development finance, bridging and equity gets it built.