Cardiff-based Opco Construction has entered administration and all 55 employees have been made redundant.
Accountants at KPMG were appointed as administrators of the contractor on 17 June.
KPMG said Opco effectively ceased trading towards the end of April 2013 with the majority of the 55 staff placed on extended leave.
Following the appointment of administrators, all employees have been made redundant.
Joint administrator and head of KPMG’s restructuring team in Wales Joff Pope said: “The economic downturn has negatively impacted the UK construction sector and these difficult trading conditions resulted in severe liquidity problems for Opco, leading to the ultimate demise of the business.
“We are now in the process of realising the company’s assets, which consist of development land in Cardiff and Swansea, and a debtor book.”
Opco is a Cardiff-based company providing design and technical services to the construction industry and operating in south Wales, the South West and the South East.
According to its website, Opco had over 70 employees based in Cardiff and Exeter.
In February it began work on a £6m contract to refurbish Swansea’s Glynn Vivian Art Gallery and a £1.5m six-storey residential and commercial building for Taylor Wimpey on the banks of the River Usk, in Newport.
Swansea council is now looking for a new contractor to complete the refurbishment of the Glynn Vivian Art Gallery.
A council spokesman said: “The process of appointing a contractor will take three months and we expect them to be on site a month later.
“We’ve worked closely with our partners, the Welsh Government and Arts Council of Wales, and have taken immediate steps to ensure this scheme moves forward as quickly as possible.”
The council added that Opco had been part of a detailed procurement process that included thorough financial and credit checks.
The refurbishment project is expected to be completed within its original £6m budget.
A Taylor Wimpey spokesman said: “We have already taken appropriate measures to ensure that work continues to deliver much-needed employment and high-quality waterside homes to the City of Newport.
“We were saddened to hear of Opco going into administration, having worked with the company successfully on a number of multi-storey projects in recent years,” he added.
Other recent clients have included the Ministry of Defence, University of Cardiff, Torquay United Football Club and Cardiff International Airport.