New figures from CITB-ConstructionSkills show the number of 16-19 years olds in the industry has fallen by 52% since 2008 while 17% of the workforce is now within 10 years of retirement.
The number of older workers aged 55 years and over in the industry has increased by 65% since 1990, while those aged 24 and under has fallen by more than 40% over the same period.
The trend has accelerated over the last 20 years and now affects professionals such as architects, surveyors and engineers as much as trade occupations.
While the increasing age profile is most pronounced in the manual workforce, professional trades could also stand to lose 19% of their manpower to retirement in the next decade.
CITB-ConstructionSkills chief executive Mark Farrar said: “CITB-ConstructionSkills is working hard to attract new blood into the industry because if we don’t act now this retirement timebomb could compromise our ability to benefit from the up-turn in the economy when it comes.
“In 1990, more than one in five (22%) of workers in the construction industry was aged 24 and under but today, little more than one in 10 of the sector’s workforce (12%) is within this age group.
“The industry lost a lot of 16-24 year olds during the last recession and while numbers had started to recover over the last 10 years the most recent recession has again had a fairly disastrous impact on young people in the sector, particularly 16-19 year olds.
“There are fewer job vacancies available at the moment, but it has also impacted badly on the perceived attractiveness of the sector in the eyes of many young people in terms of it not offering stable and progressive career opportunities.
“The risk is that the ageing workforce, coupled with a failure to train and attract sufficient people now, will result in a skills vacuum and manpower shortage in the future.”