Canberra resident Simon Bush learnt he had needed building approval to replace his tile roof with colour bond material after works were finished, when he sought a building inspector's report.

He said when he checked a government website on rules for development and building approvals, it confused the matter further by saying no approval was needed.

Mr Bush said the website was misleading and that clearer guidance was needed to stop residents from renovating their home without approvals.

"It's ambiguous, there's a lack of clarity, and how many people are caught up in it?," he said.

"I just want to make sure the next person isn't undone by it.

"There is a potential for many, many Canberrans to have non-compliant homes as a result."

The website says exemptions from building approval may apply to certain external refinishing of buildings, including changing roofing from tiles to metal sheet. It later says "no specific building approval exemptions apply", language Mr Bush said was unclear.

A Planning Directorate spokesman said the website was correct and did not say replacing a roof required no building approval.

"We will review the information provided to clarify where people can find more information on exemptions and remind people they need to check whether the specific work they are proposing needs a building and/or development approval," he said.

"As with all development proposals we encourage people to contact us or engage professionals to help them navigate the process."

The Planning and Land Authority provides free pre-application meetings to discuss development proposals.

Building approvals, separate from development approvals, ensure that planned work will be structurally sound and safe, and conforms with the requirements of the Building Code of Australia.