Balfour staff and subcontractors on 750 sites will stop work for an hour with at least 20,000 people taking part.
The “safety stand down” is an annual event now in its third year.
Nicholas Pollard, Chief Executive Officer, Balfour Beatty Construction Services UK, said: “We are standing down so we can take the time to remind ourselves of the importance of sending everyone home safe every day from everywhere we work.
“It is a short, structured pause for everyone to reflect on how they can contribute to improving safety through thoughts, words and deeds.”
This year’s main message is how vital effective daily activity briefings are to site safety.
Site leaders are also making sure that workers are encouraged to come forward with suggestions about how site safety can be improved.