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The Construction Capital podcast is the UK property development market, decoded. Hosted by Georgina, each episode breaks down a specific UK location or finance topic using proprietary transaction data, live regeneration pipelines, and the real-world lender dynamics shaping development finance today. Published by Construction Capital, an independent capital advisory brokerage sourcing terms from over 100 lenders across development finance, bridging, mezzanine, and equity. For developers, investors, and brokers who want the numbers that actually matter.
Welcome back to the Construction and Capital Podcast. I'm Georgina, and this is the London £650 per square foot deep dive. A full episode dedicated to what is, quietly, the single most important number in London property right now. If you took just one number out of London property development in 2026, it would be £650 per square foot. That is the threshold Molyos' analysis identifies as the binary line between viable and undeliverable for residential schemes across Greater London.
Georgina:Below it, the maths does not work on current build cost, finance pricing and end value economics. Above it, schemes are being underwritten and built. The most striking implication: of the 281,000 unbuilt consented homes across the 33 London boroughs, only 119,200 sit above the threshold. The other 162,000 are effectively undeliverable on current economics. That is more than half of London's planned housing stock sitting on consents that will not translate into deliveries, unless either values rise or build costs fall meaningfully.
Georgina:Let me put that in context: the six fifty number is not a planning artefact. It is a build cost versus GDV equation applied at the senior debt stage. Lenders are not negotiating it, they are applying it as a yes or no filter on the GDV input row of every appraisal that comes through the door. The reason it became binary in late twenty twenty five is the combined effect of three pressures. The first is build costs.
Georgina:UK build costs climbed roughly 22% between Q1 twenty twenty two and Q4 twenty twenty five. That is a substantial compression of the gross development margin envelope for schemes that had originally been underwritten on lower assumptions. The second is debt margins. Senior debt margins widened sharply post the twenty twenty two minutei budget, and they only partially reversed after the December 2025 Bank of England cut to 3.75%. Even at the headline base rate, lender margins have not fully normalised.
Georgina:The third is end values. Across most of Greater London, end values have been flat to down through 2024 and 2025. The London index fell 3.3% year on year in February 2026. Inner London prime fell harder, Westminster down 10.8%, Kensington And Chelsea down 11.2%. Each pressure on its own would have been manageable.
Georgina:Together, they pushed the marginal scheme below the financeability line. Now where does the line actually fall borough by borough? The threshold splits London cleanly. Most of the prime central postcode still clear it on price even after recent corrections, but with rising build costs eating much of the headroom, Westminster And Kensington And Chelsea are down sharply, but average values in those boroughs still sit comfortably above £1,200 per square foot, so they clear just with thinner margin. In the connected outer ring, the threshold is the active question.
Georgina:Walthamstow, Redbridge and Croydon clear it on transport adjacent sites. Bromley clears it in Town Centre Regeneration. Further out, in parts of Bexley, Havreng, Hillingdon and Sutton, only specific microlocations near rail nodes clear it. Many sites do not. For the major regeneration platforms, the threshold has been priced in from the master plan stage.
Georgina:Old Oak And Park Royal, Royal Docks, Earl's Court in Hammersmith and Fulham, Meridian Water in Enfield, Canada Water in Bermondsey and Southwark, Brent Cross Cricklewood in Barnett. All of them sit above the line on the proposed product mix. So what does the threshold mean for capital structures? Below the line, schemes are not financeable through conventional senior debt. They need either a change of use angle that lifts GDV, a meaningful equity component to absorb the gap, or a public sector partner taking specific risk off the table.
Georgina:We are seeing several outer borough schemes quietly PBSA or BTR, specifically because the institutional take out values clear the threshold where open market resi values do not. At the line, schemes are financeable but tightly. Senior development finance prices around 6.5% to 7% per annum, at 65% loan to GDV. Mezzanine layers in to take leverage to 90% of cost at 12% per annum. The all in blended cost lands in the 7.5 to 8.5 range.
Georgina:Workable, but it demands cost certainty. Above the line, pricing tightens by 25 to 50 basis points across each layer. Forward funding takeouts from BTR or PBSA institutional buyers re enter the conversation. That is the structural advantage of schemes that clear the threshold by 100 to £200 They get the pricing benefit on the way in and the take out optionality on the way out. Three forces could move the £650 number meaningfully through 2026 and into 2027.
Georgina:The first is rates. The December 2025 bank rate cut to 3.75% has already partially flowed through senior margins. Further cuts of 50 to 75 basis points would lift the financeable share the consented pipeline by an estimated 18,000 to 25,000 homes, those schemes currently sitting just below the line. The second is build costs. UK construction tender price inflation moderated through 2025 but remains positive.
Georgina:A flat or declining tender price index through 2026 would compound the rate effect. The third is the policy package. The time limited planning route at 20% affordable housing by habitable room combined with the Mayor's emergency measures and the second NPPF consultation outcome materially improves the GDV input on a meaningful slice of consents. For the right scheme in the right borough, the policy uplift alone is worth per square foot. That is the difference between a scheme that does not clear and one that does.
Georgina:To wrap up, what this means for site acquisition. If you are pricing a London site in 2026, the threshold question is the threshold question. Run the appraisal at £650 per square foot first. If it does not clear at credible build cost, the site is not financeable through conventional channels, regardless of how attractive the land basis looks. Where appraisals do clear the threshold, the next questions are the obvious ones: Planning runway Infrastructure cost allocation Capital structure fit But the threshold filter removes most of the bad questions before they reach lenderdecks.
Georgina:For full borough by borough sold price data, viability scenario modelling and the underlying capital stack benchmarks behind this analysis, head to constructioncapital.co.uk and look for the Greater London 2026 Market Report. If you found this useful, subscribe to the Construction and Capital Podcast on Apple, Spotify, or wherever you get your podcasts. The full Greater London 2026 episode is 20 angles deep. The viability cliff is just the foundation question. I'm Georgina.
Georgina:Until next time.