A construction sector voice says mandatory home warranties are well overdue.

The Government's announced plans to require warranties for new homes three storeys or less and all renos worth at least $100,000.

Building and Construction Minister Chris Penk says it hopes to protect homeowners from cowboys.

Certified Builders Association Chief Executive Malcolm Fleming told Ryan Bridge it will cost more, but only marginally.

He says it will make up 0.4% of a $200,000 project.

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