Owner of P and K Roofing Pat Murphy met with his accountants in a last ditch attempt to save the firm, but was told the company could not survive and it was placed in administration on Friday.
Mr Murphy told the Bolton News: "My accountants just said you can't survive this and I've had to let the men go.
"Some of them have been with me since we set the firm up 12 years ago. I wanted people to know what has happened because this will affect our suppliers down the chain and other companies may be dragged under.
"At our peak, we employed 35 slate tilers and now at the age of 58 I don't know what I want to do. Before Rok went under, we were a solvent company and we were doing quite nicely."
He claims Rok was due to pay his company £100 000 for work already carried out on 7 November - the day Rok went into administration. P and K Roofing was also due to receive further payments from Rok in December and January.
Mr Murphy said that subcontracting to Rok constituted around 80% of his company's work.