The expert firm hired by Boral’s independent directors has cut its valuation range for the building materials group after criticisms by Kerry Stokes’ Seven Group Holdings, which claimed a week ago that there were fundamental errors in its work.

But Grant Samuel’s lower valuation has not changed the advice from Boral’s independent directors that shareholders should reject Seven’s $1.9 billion buyout offer. Seven had previously said its work had “fundamental errors”, leading Grant Samuel to lower its valuation range for Boral by 8¢ per share in a note to investors.