London’s housing delivery slowdown between 2024 and 2026 is often described as a market failure or a planning issue. In practice, it is increasingly a programme risk problem. Building safety regulation, introduced to address legitimate post‑Grenfell failings, has altered the sequencing, certainty and cashflow profile of high‑rise residential development to the point where regulatory approval itself now determines whether projects start at all.

This is not a debate about whether regulation is necessary. It is an examination of how the current approval architecture interacts with London’s delivery model and why that interaction has materially changed programme risk across the capital.

The scale of the delivery slowdown

Housing delivery data between 2024 and 2026 shows a contraction in London that is historically severe and structurally distinct from the rest of the UK.

Housing starts in London fell by approximately 72% in the 2024–25 financial year, with fewer than 4,500 homes commencing construction compared with over 15,000 the year before. Completions fell to around 30,000 homes in 2024, roughly 36% of the annual housing need identified in London Plan modelling. Affordable housing delivery has been hit particularly hard, with major housing associations reporting a two‑thirds reduction in new starts over the same period.

What differentiates this downturn from previous cycles is not demand. London continues to face acute housing pressure. The constraint is the point at which projects move from consent to construction.

How the regulatory model changed

The Building Safety Act 2022 replaced the previous building control regime for Higher‑Risk Buildings with a gateway‑based approval system enforced by the Building Safety Regulator. The most consequential change for programme risk sits at Gateway 2.

Gateway 2 introduced a mandatory hard stop before construction can begin. Unlike the previous system, where work could often proceed under an initial notice with conditions resolved in parallel, construction on HRBs cannot legally start until full approval is granted. Designs must be completed and effectively frozen to RIBA Stage 4, supported by detailed fire and structural strategies, competence declarations and a formal change control framework.

This has shifted risk earlier in the programme and removed much of the flexibility that historically allowed London schemes to absorb regulatory interaction without stalling.

Gateway 2 as a programme bottleneck

Between 2024 and 2026, Gateway 2 approval times in London consistently exceeded statutory targets by a wide margin. While the statutory determination period for new‑build HRBs is 12 weeks, observed approval times in London averaged close to 48 weeks through much of 2025.

The effect has been cumulative. By late 2025, industry bodies reported that close to 10,000 London homes were awaiting Gateway 2 approval for more than six months, with some projects delayed for nearly a year. London accounts for the majority of the BSR’s national workload, with roughly 69% of decisions in late 2025 relating to London schemes.

Although a dedicated Innovation Unit introduced in late 2025 has reduced approval times for a subset of new applications, the underlying exposure remains: programme critical paths now pass directly through a regulator with finite capacity and a sequential approval model.

Consequences for live programmes

The programme effects of this shift are visible on sites across the capital.

Construction sequencing is now fully dependent on regulatory clearance, creating idle periods where land is owned, finance is accruing and no physical progress is permitted. Industry reporting in 2025 identified more than 150 tower cranes standing idle on London sites due to Gateway 2 delays alone.

The impact extends to completion. Gateway 3 operates as a legal barrier to occupation, requiring full as‑built evidence, commissioning records and signed dutyholder declarations. Occupation before certification is a criminal offence. As a result, completed homes can remain empty while approval is finalised. By late 2025, approximately 1,300 completed flats in London were reported to be awaiting Gateway 3 certification, directly delaying sales and cashflow.

Any material change during construction (including adjustments to wall build‑ups, fire stopping details or floor layouts) triggers formal change control and, in some cases, re‑approval. These interventions can pause works mid‑sequence for weeks, compounding delay risk.

Viability effects in high‑density schemes

London’s housing model relies heavily on high‑rise and high‑density delivery. This makes it particularly sensitive to regulatory friction applied at the building level.

The introduction of the second staircase requirement for residential buildings over 18 metres has reduced net saleable area while increasing construction cost, disproportionately affecting schemes on constrained urban sites. At the same time, the need to complete and submit detailed designs earlier in the programme has shifted significant cost and risk forward, increasing exposure before certainty of approval.

For marginal schemes, the combined effect of delayed starts, extended finance periods and reduced yield has been sufficient to halt projects entirely. Multiple industry surveys conducted between 2024 and 2026 identify building safety approval risk as a primary factor in decisions to pause or abandon London schemes.

Why London is affected differently

The impact of the gateway regime is not evenly distributed across the UK. London contains a far higher concentration of buildings that fall within the Higher‑Risk Building definition, meaning a greater proportion of its housing pipeline is subject to full BSR control.

While low‑rise housing outside London has shown resilience, the capital’s apartment‑led delivery model places it directly within the most regulated segment of the market. This structural exposure explains why housing starts in London diverged sharply from national trends during 2024–25, despite similar economic conditions.

A programme risk, not a policy debate

Between 2024 and 2026, building safety regulation in London has moved from an administrative compliance layer to a primary determinant of programme certainty. Approval timing, evidence sequencing and change control now sit on the critical path of residential delivery.

Recent efforts to increase regulatory capacity and streamline decision‑making may ease some pressure, but the underlying risk profile has changed. Until approval timelines become predictable and proportionate to programme planning, building safety regulation will continue to suppress housing starts in London regardless of demand or planning consent.

This is not a question of whether safety standards should exist. It is a recognition that, in their current operational form, they now define the pace and viability of housing delivery in the capital.

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Expert Verification & Authorship: Mihai Chelmus Founder, London Construction Magazine | Construction Testing & Investigation Specialist