Trade creditors are owed at least $12.5 million in the collapse of Bob Day's Home Australia group of building companies.
The ASX-listed Brickworks is among the hundreds of suppliers and trades people who will be contacting the liquidators McGrath Nicol who are still assessing the full extent of the collapse.
Brickworks had liabilities in excess of $1 million to Senator Day's group, its chief executive Lindsay Partridge said.
"Bob is a good friend and a great customer," Mr Partridge told The Australian Financial Review.
"It's a shock for us. We were supplying them nationally."
The housing group went into liquidation on Monday, leaving up to 230 houses around Australia still under construction.