The firm also warns that the delay will be felt across the country once the Government introduces proposals for 11-storey and above block of flats across the country.

In its latest tender price forecast for the UK, the cost consultant warned the new fire safety-based design delay would worsen the wider market slowdown.

Simon Rawlinson, head of Strategic Research & Insight at Arcadis, said that London’s high rise residential market should brace for significant delays following the GLA’s accelerated introduction of a mandatory second staircase requirement for all new residential buildings over 30m.

While many affected buildings are part of long programmes, offering time for redesign, in reality all taller residential developments currently in procurement will likely be postponed by 6-9 months for redesign, he warned

The impact of this will likely spread to regional markets once the staircase requirement is confirmed nationwide.

He said: “Our view is that loss of workload associated with second staircase delays is a material factor influencing market conditions in London, with an anticipated reduction in tender price inflation to 2% in 2023.”

The forecaster also predicted materials price inflation and shortages were behind the industry now as stock levels on products like bricks return to more normal levels and energy prices.

Looking ahead, Rawlinson said: “Even if 2023 turns out to be better than forecast, we will see a significant slowdown compared to the past two years.

“Our view is that building workload will stabilise in 2024 at new but mostly reduced levels and that the greatest area of uncertainty will be the rate of growth of work to power and water networks.”

For 2025, Arcadis forecasts prices across all sectors will rise by 3-4%. This is a marginal upgrade reflecting the potential for some bounce back in price pressure as workload picks up.