An estimated extra 140,000 construction workers would be needed for each of the next five years to help retrofit all social and private homes under the government's Warm Homes Plan, the BBC has learned.
In its manifesto, Labour committed to insulating and upgrading five million homes over the next five years to cut bills for families and slash fuel poverty.
The Construction Industry Training Board's (CITB) scenarios also estimate 61,000 new workers each year would be needed to meet the government's target of 1.5 million new homes by 2030.
The government said it was investing £600m to create up to 60,000 more engineers, bricklayers, electricians, and joiners by 2029 to tackle skills shortages and to help deliver its target.
CITB chief executive Tim Balcon says the construction industry has "the capabilities to meet current demand" but this "won't happen overnight".
Currently, it is really difficult to coordinate training in the industry, he says, because there are "lots of different systems at play", with many subcontractors and training colleges.
Mr Balcon adds that "everybody wants to do the right thing but they're not aligned".
The BBC spent a day on a 575-home development site in Southall, west London, speaking to several of these parties.
The apprentice
Plumbing apprentice Will Cunningham, 24, was recruited through a local labour scheme in March.
"I didn't really feel like working in an office or anything like that. Wanted to do something physical... keep physical, keep fit, and it's pretty good money."
He adds getting a job in the industry was more difficult than he had expected.
"I applied for at least 20 companies before I found a job. It took about four months of looking - it was tough.
"They hire for experience - they get chosen first. So it's hard to start, but once you're chosen it's not too bad."
The CITB says the industry needs more "strongly visible" work to encourage employers to invest in training.
Its Construction Workforce Outlook forecasts an extra 240,000 construction workers will be needed over the next five years.
According to the board, this number would need to increase significantly depending on progress measured against policy ambitions.
The CITB's scenarios indicate that, to meet the aspiration of building 1.5 million new homes, an extra 61,000 workers will be needed every year for five years.
Similarly, an extra 140,000 workers will be needed every year for five years to retrofit all private and social rental properties to an EPC-C rating, as the government hopes to achieve with its Warm Homes Plan.
The government is set to announce further details in the Warm Homes Plan later this year.
However, data seen by the BBC shows residential applications for heat pumps has dropped during 2025 after a steady increase since 2021.
Ed Griffiths, head of business and client analytics at construction data experts Barbour ABI, said: "Given that the government has set out its ambition to support the growth of the heat pump market to around 600,000 installation per year by 2028, there will obviously need to be a bigger installation drive in all areas combined with a push for more trained installers."
The plumbing manager
Ian Berney, managing director of RG Taylor Engineering, says they employ five apprentices a year.
"It's been difficult to get people in when we haven't been as busy as we normally are."
He says developers "are finding it very difficult to get planning across the line", adding: "Consequently, we end up with a backlog of jobs that need to be progressed.
"I think by the time next year comes around we're going to see a lot of sites not started because of Gateway 2. I think if that could change so we can speed the process up, recruitment will come into it tenfold."
Gateway 2, within the UK's Building Safety Act 2022, is a mandatory pre-construction approval stage for higher-risk buildings.
In June, the government announced new reforms to the building Safety Regulator to address delays to building new high-rise homes, including a fast track process, changes in leadership, and plans to establish a single building regulator.
The developer
Mike Keaveny, director of land and development at Grainger, says in the past few years, labour shortages have made it much more expensive to build.
"Developers and contracts are finding it hard to find basic trades like bricklayers, ground workers, plumbers, scaffolders, so we're having to work our way round that shortage as best we can.
"Sometimes you have to delay works but we're also pivoting to different types of construction."
On the Southall development site, parts of the building are made in a factory offsite, including panels and pre-plumbed bathroom pods, which has helped to keep the project on track.
"Building off-site can be more efficient in terms of wastage as well. The industry is pivoting towards that, particularly in high-rise buildings," Mr Keaveny says.
Mr Balcon says in order to solve the shortage of construction workers, the industry needs to focus on retention and productivity.
"The industry recruits about 200,000 people every year, and it loses 200,000 people every year. If we were to address the retention of skilled workers, that would relieve some pressure on the amount of people we have to bring into the industry.
"The other factor is the productivity of the sector. Construction really has lagged behind in terms of its productivity by 1% - that's the equivalent of 33,000 workers."
He also highlighted the problems with "word-of-mouth" recruitment, which means "the visibility of those jobs is sometimes quite hard to see".
He says a regional approach is needed "to understand where those hotspots are - areas of high demand. In London the demand for construction is huge. You can just look at the skyline to see that."
A Department for Energy Security and Net Zero spokesperson said: "The energy shocks of recent years have shown the urgent need to upgrade British homes.
"We are already training 18,000 skilled workers to work on heat pumps, insulation, heat networks and solar panels, while working closely with the construction industry to train many thousands more – resulting in lower bills and warmer homes for millions of families.
"We will announce further details in the Warm Homes Plan later this year."
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