Daniel Dennis, 17, died in April 2003 after he fell through a skylight at a Matalan store in Cwmbran, Gwent.
He was working for Bridgend firm North-Eastern Roofing, which was subcontracted to Midas Construction. North-eastern owner Roy Clarke will be charged with manslaughter.
The CPS decided not to prosecute for gross negligence manslaughter in March 2006.
But this decision was quashed by the High Court last Decem-ber following a challenge brought by family lawyers, instructed by the GMB union.
Gwent CPS said it will now prosecute Mr Dennis’ employer. The family’s solicitor Mick Antoniw said: “There are lessons to learn. In future, it’s essential for the CPS to become more proactive and to take a greater interest in workplace fatalities and develop greater expertise in health and safety law.”