The Government has defended allowing construction work to continue despite the lockdown measures.
Builders and construction workers have said they feel “angry and unprotected” going to work following the introduction of the stricter anti-Covid-19 measures.
Prime Minister Boris Johnson placed the UK on lockdown on Monday evening.
But Downing Street said that construction work should continue if it can be done following Public Health England and industry guidance.
The Prime Minister’s official spokesman said on Tuesday that the Construction Leadership Council had issued guidance to the industry.
He added: “It should continue where it can happen in a way that follows Public Health England and industry guidance.
“We urge employers to use their common sense when managing live projects and ensuring that employees can follow the Government guidance and practice safe social distancing on site.”
London Mayor Sadiq Khan has said he told Mr Johnson “forcibly” at a Cobra meeting that construction workers should not be going into work.
After more scenes of packed Tube trains on Tuesday morning, Mr Khan was asked if construction workers in London should be among the travellers.
He told ITV’s Good Morning Britain: “My view is no, and I made that point quite forcibly at yesterday’s Cobra, I made that point quite clearly to the Prime Minister.
“According to the Government’s advice the answer is yes.”
A crane operator at a London construction site with 400 to 500 workers said: “Everyone on site at the minute feels angry and unprotected.”
The man, who asked not to be named, said if he opted not to go in he “wouldn’t get paid or even could lose my job”.
“(It’s) scary really – I’ve got a family and kids at home. I’m in London around all these people, bringing it all back into an isolated home.”
Electrician Dan Dobson said the Government must provide support to self-employed workers, including about a million in the construction industry, and then shut down building sites.
He added: “They have no incentive to stay at home, they have bills to pay.
“Everyone on site at the minute feels angry and unprotected.
“None of them want to go to work, everyone is worried about taking it (coronavirus) home to their families.
“But they still have bills to pay, they still have rent to pay, they still have to buy food.
“Construction sites will stay open until the Government issues an order to close.
“But the Government cannot issue the order to close until it offers support to the one million-plus construction workers – it has to go hand in hand.”
British Safety Council chairman Lawrence Waterman said that all non-essential construction work should be stopped so that workers can stay safe.
He added: “The construction sector needs clarity from the Government – on most sites social distancing will be impossible or simply unsafe.
“All non-essential construction should end now so that construction workers can go home and stay home like everyone else.”
While some companies said they were closing sites down and suspending work, others said they would remain open with “strict precautions” in place.
Transport for London (TfL) announced on Tuesday that work on its Crossrail sites was being temporarily suspended but that essential maintenance of the transport network will continue.
Aylesbury Tory MP Rob Butler said he had told ministers that work on HS2 should be stopped after contractors in his area were failing to comply with social distancing.
He tweeted: “Following shocking reports of @HS2ltd contractors failing to comply with social distancing & even coughing over local people, I’ve told the #HS2 minister that work must stop now, to protect the health of my constituents. Yesterday I wrote to the CEO calling for an immediate halt.”
HS2 said its “joint venture partners” are responsible for their sites and the health, safety and well-being of their workers.
A spokesman added: “Over the course of this week and into next, we will be reviewing the majority of works on our construction sites in-line with government advice on dealing with Covid-19.”
House-builder Taylor Wimpey also said it has closed its construction sites, show homes and sale sites.
But earlier on Tuesday, rival Redrow said its sites remain open with “strict precautions in place including enhanced levels of cleaning, additional hygiene facilities and social distancing”.