Demolition companies say a law change is needed to make them more accountable for the contents of buildings.
The call follows reports that items from the red zone in Christchurch are being dumped unnecessarily.
The Demolition and Asbestos Association says the law should require crews to make contact with the owners of a building's contents before the building is cleared out.
Association president Diana Stil says at the moment items to be retrieved are specified in a contract agreed to between a demolition company and a building's owner.
However, sometimes building owners fail to tell the contractors what the tenants want salvaged.
Mrs Stil says most demolition crews let the owners know about valuable contents that can be safely retrieved but some will only salvage those listed in the contract.
She says that can lead to the unnecessary dumping of valuable materials.
