A Freedom of Information (FOI) request to the HSE by construction union UCATT revealed that 552 unannounced inspections took place in 2014/15. This is 55.7% less than the 1,248 inspections in 2012/13.
UCATT said this decline took place as the sector was recovering from the recession and construction activity was increasing.
"These findings are shocking," said Harry Frew, regional secretary for UCATT Scotland. "It is only the prospect of an HSE inspector knocking on the door which means that many construction employers comply with safety laws. If that deterrent doesn't exist then employers are going to be increasingly tempted to cut corners and risk workers' lives."
The fall in inspections is reflected in a drop in formal enforcement action. The number of formal notices issued to companies following an inspection has decreased by 25% and the number of prohibition notices has fallen 33%.
Frew added: "The HSE needs to explain why this reduction has happened. Is this due to budget cuts or a result of specific HSE policies? Scottish construction workers deserve to be told the truth."
