The Building Safety Act is not the only thing stopping us from building upwards

That logic for higher density is well understood by planners and policymakers: it is acknowledged that higher-density development supports sustainable transport, makes better use of existing infrastructure and helps to underpin town centres and local services.

In theory, it is an efficient response to constrained urban conditions. In practice, delivering density has become increasingly difficult, due to market and regulatory factors.

The Building Safety Act 2022 was introduced with the important objective of tightening the regime and restoring confidence in higher-risk buildings following the Grenfell Tower fire. Few in the industry would dispute the need for a stronger safety regime and more effective oversight. However, its implementation has brought with it approval bottlenecks with knock-on effects on how and where developers are prepared to build.

“Although the levy is modest when viewed in isolation, it does not operate in isolation; it sits alongside high affordable housing requirements, biodiversity net gain, energy performance standards and Community Infrastructure Levy (CIL) charges”

The requirement for Building Safety Regulator sign-off at Gateway 2, before works can begin on higher-risk buildings, has introduced a new layer of uncertainty into development programmes. Target timescales are frequently exceeded, and in the absence of settled precedent, developers are often unable to predict how long approvals will take. For schemes that rely on height to achieve viability, this uncertainty quickly becomes a material risk.

The problem is compounded by cost pressures. The requirement for second staircases in buildings over 18 metres reduces net internal area and efficiency. Furthermore, compliance costs add up across design, procurement and construction, and taken together, these factors have encouraged a shift away from taller buildings towards mid-rise.

The forthcoming Building Safety Levy adds another layer to an already complex viability picture. Although the levy is modest when viewed in isolation, it does not operate in isolation; it sits alongside high affordable housing requirements, biodiversity net gain, energy performance standards and Community Infrastructure Levy (CIL) charges, all at a time when the government’s Help to Buy scheme has been phased out and registered providers are focusing investment on their existing stock.

On marginal urban sites, where density is often the only route to making schemes stack up, these cumulative burdens matter. The levy is payable early in a scheme’s life and in full, which has implications for cashflow as well as headline viability. For larger developers this may be absorbed, albeit reluctantly. For smaller developers who lack the same economies of scale, the impact is proportionally greater.

Due to the rapid slowdown in completions in London as a result of recent regulatory changes and general market conditions, the GLA is consulting on changes to its affordable housing policies for a short, temporary period to help stimulate the development market, most notably a reduction in the fast-track affordable housing planning route threshold from 35% to 20% on privately owned sites.

The government is also consulting on providing CIL relief for residential schemes in London, also for a shorter period. Whether the short period of time for implementation can make a real difference to market activity remains to be seen.

Alongside safety and cost, potential leasehold reform adds another layer of uncertainty. The government has stated its ambition to move towards commonhold for new flats and a Draft Leasehold and Commonhold Reform Bill is expected imminently.

Commonhold remains largely untested at scale in England and Wales. The majority of developers are cautious about being early adopters, lenders remain unconvinced about risk and security and buyers are wary of a step into the unknown.

“Mid-rise buildings, typically between six and 10 storeys, can achieve high densities without triggering the most onerous aspects of the higher-risk regime”

From my perspective, a balanced approach is essential. Reforming leasehold to address its shortcomings while building confidence in commonhold over time would allow the market to adjust. Moving too quickly risks undermining the apartment market on which higher-density delivery depends.

There are ways to reconcile density with safety and deliverability. Mid-rise buildings, typically between six and 10 storeys, can achieve high densities without triggering the most onerous aspects of the higher-risk regime (although any residential scheme of seven storeys or at least 18 metres high requires approval from the Building Safety Regulator). Mansion blocks and perimeter blocks deliver efficient layouts and good amenity while sitting comfortably within established urban fabric.

Construction methods also matter. Robust structural systems, simple geometries and repeatable design solutions are easier to verify and less prone to delay. Early engagement with the regulator, particularly where modern methods of construction are proposed, can reduce risk later in the process.

Crucially, the regulatory system itself could evolve. A more proportionate approach for simpler or mid-rise schemes, clearer guidance on Gateway submissions and better integration between planning and building control would all improve predictability without compromising safety.

The need for density is not going away. If anything, it will intensify as housing targets remain under pressure and urban land becomes scarcer. The question is whether the current framework allows that density to be delivered at scale.

Safety must remain paramount. But safety delivered through uncertainty, delay and cumulative cost risks suppressing supply. A more calibrated approach, one that recognises different levels of risk, supports viable schemes and manages reform carefully, would help to close the growing gap between ambition and delivery.

Chris Hemmings, partner, Carter Jonas