Australian building products company Crane Group says appraisers believe Fletcher Building's hostile takeover offer is unfair and undervalues the firm by about 14%.
Fletcher Building, which already owns 14.9% of Crane, launched an $835 million cash and scrip takeover offer for the rest of the company in December.
Crane quickly rejected the offer as too low, but commissioned Ernst and Young to prepare an appraisal report on the offer.
The report isn't being sent to shareholders until next week, but Crane says it concludes the offer is neither fair nor reasonable.
Crane says the experts believe the company is valued at between $A9.92 and $A11.56 a share, whereas Fletcher's offer is now worth between $A9.05 and $A9.45 a share.
Fletcher Building says it won't comment on the issue until it has reviewed the full appraisal report and worked out how the value was calculated.
The takeover offer closes on 25 February and is conditional on Fletcher acquiring 90% of Crane.
The Commerce Commission is considering whether the takeover will reduce competition in the market, and is expected to release its decision shortly.