Planned standards for properties which have housed P-labs must ensure landlords are not taken for a ride by cleaning companies, property investors says.
The government is putting up more than $60,000 towards developing standards for remediating properties contaminated with methamphetamine.
Property Investors Federation executive director Andrew King said it also wanted clearer guidelines about when and how P-houses should be decontaminated, and what level of the drug was safe.
Some homeowners were being charged for services which were not necessary, and people were potentially overcleaning, he said.
"They're not too sure when they actually need to clean, what the adverse health affects are on people living in the house and what levels actually need to have some cleaning done."
Mr King said he hoped the new standards were not expensive for companies to comply with, as the costs would be passed on to homeowners.