The Prime Minister highlighted construction as he announced plans to restart the economy while containing the spread of covid-19.
Johnson said: “We now need to stress that anyone who can’t work from home, for instance those in construction or manufacturing, should be actively encouraged to go to work.
“And we want it to be safe for you to get to work. So you should avoid public transport if at all possible – because we must and will maintain social distancing, and capacity will therefore be limited.
“So work from home if you can, but you should go to work if you can’t work from home.
“And to ensure you are safe at work we have been working to establish new guidance for employers to make workplaces covid-secure.
“And when you do go to work, if possible do so by car or even better by walking or bicycle.”
Government advice during the pandemic has always been that construction can continue.
Most sites closed when lockdown started in March followed by a gradual return to work which has picked-up pace in recent weeks.
Build UK’s latest figures show that work has already restarted on 73% of its contractor member sites.
But productivity is still well down with work levels on infrastructure and construction sites averaging 71%, up from 67% the previous week.
Sites in London remain a particular challenge although output has improved from 56% to 63% in the last week.
The Scottish Government has not changed its advice that all but essential construction sites should remain closed.