Since its launch in 2015 the fund has awarded over £21.6m to construction companies employing less than 100 people.
The fund is now being boosted and expanded to cover bigger firms employing between 100 and 250 people.
It is now open for applications with £14m available for contractors to claim this year.
Small and micro firms can apply for up to £10,000 in training grants and medium firms can apply for up to £25,000.
Training company Construction Skills People (CSP) has been instrumental in securing £1.1m for more than 150 contractor clients through the fund.
Director Stuart Anderson said: “We offer a free service to clients that sees our bid writing team put an application together that is rich in the content required to secure enough marks to make a successful application.
“At the completion of the project we also provide our clients with all the evidence they will need to provide to the CITB to substantiate that the funding has been utilised in line with the original application.”
CSP has also worked with NVQ bodies to deliver a model that allows qualifications to still be completed while working from home.
CITB chief executive Sarah Beale said: “The new CITB Skills and Training Fund has been refreshed to become a wider, more flexible offer for employers.
“We have responded to the urgent COVID-19 situation by changing the focus of the fund and offering more flexibility on what businesses can apply for.
“At the moment the main priority is doing all we can to ensuring businesses and employees are protected so that, when the current emergency finally comes to an end, the sector is armed with the skills and resources it needs to keep Britain building.”