Both firms are heading for liquidation while other parts of the wider Diamond Build Group are unaffected.
Accountants at MHA are now working with the companies ahead of their planned liquidation later this month.
MHA said: “There are multiple businesses in the Diamond Build Group; however, only two of these businesses – Diamond Build plc and Diamond Fire Safety Ltd – ceased to trade on 5th January 2024.
“They have both sent notices to creditors that they will go into liquidation on 19 January 2024. A team from auditors MHA is assisting Diamond Build plc and Diamond Fire Safety Ltd with the process of going into formal liquidation but an independent liquidator will be appointed.”
Diamond Build plc is the biggest part of the group with a turnover of £26.8m for the year to December 31 2022 resulting in a pre-tax profit of £359,000 while employing 41 staff.