Hammersmith, London-based contactor PVAD was extending a basement at a site in Montholme Road near Wandsworth Common, south London, when the HSE visited in March 2017 and identified serious breaches.
There was no edge protection in several areas, including at the site entrance where workers could fall 4 m into the basement. The contractor had also installed unsafe "home-made" ramps.
The inspector found the site lavatory did not have a cistern to flush and washing facilities consisted of a cold water outdoor tap and bucket, with no soap or towel.
The HSE served a prohibition notice halting work until improvements were made. However, follow up inspections in April and May 2017 found new work at height issues that were so serious the inspector had to close the site down on both occasions until it was made safe.
HSE inspector Adam Thompson said: "PVAD were provided with clear written advice to help them make improvements. They failed to take note of this and continued to rely on a site manager with no formal health and safety training."
He added: "On the three occasions the site was visited the workers were at such risk of falling that work had to halt. It was just good fortune that no one was killed or seriously injured at the site."
At the first follow-up visit the inspector also found the company had breached an improvement notice for the welfare facilities.
Westminster Magistrates' Court heard on 11 April that the HSE had inspected other PVAD sites on several occasions in 2015 and 2016. The contractor had been served with three improvement notices for poor welfare facilities and two formal letters highlighting work at height risk, which also gave advice.
Thompson said: "The standards were particularly inexcusable as the company had received clear warnings in the past."
PVAD pleaded guilty to breaching reg 6(3) of the Work at Height Regulations 2005, reg 15(11) of the Construction (Design and Management) Regulations 2015 and s 33(1)(g) of the Health and Safety at Work Act. PVAD also had to pay £1,525 in costs.
