A new report claims tougher enforcement of rules for tradies working from heights of less than three metres are unnecessary, and are drastically driving up costs for homeowners.

The regulations have been around since 1992, but have been strictly enforced since a Preventing a Falls From Height campaign from WorkSafe New Zealand came into force in 2012.

Builders have told the New Zealand Initiative compliance is adding up to $15,000 dollars to the cost of a new single storey house.

Executive Director Oliver Hartwich said it's also bumping up the cost of a new roof by $2000.

"We estimated, and this is a very conservative estimate, that this is costing the economy at least $100 million a year ... we think this regulations is unnecessary and based on what we have seen it hasn't had a considerable benefit, but has had a considerable cost."

But contractors are backing the rules which they say are just about safety.

President of the Specialist Trades Contractors Federation Graham Burke doesn't believe the figures are near as high as the report claims and says safety is key.

"When you've been a tradesman for a long period of your life you know so many people that have had falls that stay with them forever. Guys with smashed ankles or knees or various other body parts. Not to mention people end of paraplegics and all sorts of things."

Burke added the rules are simply about keeping workers safe.

"How would you like to be looking out your kitchen window every morning and see the spot that the roofer had fallen off an broken his neck because you didn't want to pay for a bit of extra protection? If people think about it like that it might bring it home a little bit."