The construction industry is accused of "squandering" its own future and that of its trainees in a damning report by the chief inspector of adult education.
The building industry may be expanding and the Government encouraging more new housing, yet most apprentices are failing to complete their training.
And, despite the shortage of workers, women and black people are still rarely seen on construction sites, adds the report by the Adult Learning Inspectorate.
The report says 40 per cent of on-the-job training it inspected was judged "inadequate".
Just 35 per cent of trainees complete their apprenticeships.
The report says the content of the training "apprenticeship framework" may be partly to blame. It is so muddled that employers are discouraged from offering it.
"There is no single cause of poor achievement," says the report. "One obstacle is the complexity of the framework itself and the demands it places on all parties involved.
"Many smaller employers find it hard to offer the variety of work on site which provides the full range of assessment opportunities that learners require."
Just 25 per cent of employers do any training at all, despite the industry's insistence that it wants more skilled people.
Nicky Perry, director of inspection at the ALI, said: "During the 1970s, 100,000 people were being trained every year im the construction skills that are needed - carpentry, plastering, bricklaying, glazing, plumbing and scaffolding to name but a few. However, last year fewer than 40,000 entered the industry, and the statistics suggest that only 34 per cent of them will complete their training.
"The largest provider of training in the building crafts is the Construction Industry Training Board, with 10,000 learners every year. Only 25 per cent of them will complete their qualification. The industry is squandering its own future by not facing up to the critical problems endemic in its training methods today."
The industry now has 300,000 fewer workers than it needs and would have to take on 88,000 new entrants each year for the next five years to reach its full capacity based on projected growth.
There are 35,000 learners on construction apprenticeships, compared with almost 100,000 in the 1970s. The report says: "It is widely accepted that this shortfall will not be met."
The ALI accused the industry of not doing enough to encourage women and members of the ethnic minorities.
But one of the report's statistics will not do much for recruitment, even among white men: the death rate. At 70 deaths a year, the construction industry accounts for 30 per cent of all work-based fatalities and is failing to meet its health and safety targets.
Course completion rates are better among trainees in areas such as gas and electrical fitting, where people have to be licensed to work unsupervised.
Mr Perry added: "The industry, particularly the CITB, should be asking itself why so much of its training is failing its apprentices when there are other areas that are doing a lot better."
While the report slates work-based training, it says colleges and other providers have been oversubscribed with people wanting to do construction courses. Carpentry, joinery and plumbing proving the most popular.
Colleges have struggled to recruit skilled lecturers in these subjects and have lacked the money to invest in workshop facilities.
Further education colleges are the largest provider of off-site training for construction workers.
But, despite the difficulties, colleges enjoy a good reputation with employers. Forty-three of the 45 construction centres of vocational excellence are in colleges.
The vast majority of employers told the ALI that colleges provided "high-quality learning opportunities" and that they would recommend the college they use to other employers.