The FMB and Chartered Institute of Building (CIOB's) latest State of Trade Survey reveals that 40% of firms cited extreme weather or climate events as a cause of project delays in the second half of 2025, making it the single biggest factor ahead of planning delays (36%) and market uncertainty (35%).

Nine in 10 firms experienced some form of delay over the period, up from eight in 10 in the first half of the year.

In particular, with a heatwave in most parts of the UK this week, the FMB has warned of the implications of severe heat.

Not only does this result in slower working conditions, but the federation has recommended the use of mandatory rest breaks and rescheduling outdoor tasks during the hottest parts of the day due to health concerns.

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The FMB is urging member firms to ensure workers have access to shade, regular hydration, and sun cream with a minimum SPF 30 and reminding clients that responsible employers will adapt working patterns when the mercury rises.

"Heat exhaustion and sunburn can put skilled tradespeople out of action and put projects back further,” said Brian Berry, CEO at the FMB.

“We'll be watching the weather data closely in our next survey, but the direction of travel is clear — extreme weather is becoming an increasingly serious operational challenge for small builders across the UK.

“Our message to firms is simple: protect your workforce and our message to clients is: a firm that looks after its workers is exactly the kind of firm you want on your job."