Hall Chadwick representatives have been appointed administrators of builders Cooper & Oxley, and Cooper & Oxley WA.
Embattled building companies Cooper & Oxley, and Cooper & Oxley WA have entered voluntary administration, which could leave some local subcontractors up to $1 million out of pocket.
Hall Chadwick representatives were appointed administrators and will assess the companies' finances, including examining current projects.
The company's director is proposing a deed of company arrangement to allow trading to continue.
An initial notice to creditors was being prepared and the administrators were organising meetings with sub-contractors.
Contractors were shocked on Monday to find they had to battle security guards to access Cooper & Oxley worksites to pick up their tools and machinery.
Subcontractors WA chairwoman Louise Stewart told AAP the group was working with more than 100 subcontractors.
"There will be a number of subcontractors whose businesses will not survive," she said.
Ms Stewart said there would also be a ripple effect on other even smaller subcontractors.
"We will be working extremely hard to make sure that we get a fair deal from administrators," she said.
The Department of Mines, Industry Regulation and Safety has contacted Hall Chadwick regarding its intentions for incomplete building work.
Meanwhile, Cooper & Oxley is suing developers Sirona Capital for more than $5 million over the Kings Square redevelopment in Fremantle.
Sirona Capital managing director Matthew McNeilly said the legal action would be vigorously defended.
He said Cooper & Oxley became a unit holder in 2011 but their investment could not be construed as a loan and their involvement was limited to their investment in the trust.
Sirona Capital is trying to release Cooper & Oxley's investment by selling their units, but Mr McNeilly said the legal action could undermine their ability to do so.
Cooper & Oxley was sought for comment.
SOME OF THE MAJOR COOPER & OXLEY PROJECTS IN WA:
* A $101 million mixed use development including seven levels of offices, nine levels of hotel accommodation and a cinema complex at 500 Hay Street, Subiaco
* A $21 million 12-storey hotel tower, which is integrated with a refurbished two-storey heritage building at 1309 Hay Street, West Perth
* The $147 million Karratha Health Campus
* A $12 million redevelopment of the Kaleeya Hospital building
* The $15 million Roebourne Regional Work Camp, which is a new correctional facility accommodating 30 prisoners and located adjacent to Roebourne Regional Prison
* The $27 million Butler Railway Station
* ALDI stores at Cockburn Central, Morley Galleria, Currambine and Banksia Grove.
Source: Cooper & Oxley website