Defence audited its 30,000 buildings following the deadly Grenfell Tower fire in London in June 2017, initially finding 208 buildings could be at risk.

Fire engineers have since narrowed the list down to five non-compliant buildings in four states, a Senate committee has heard.

"These buildings are essentially low-rise buildings, they're not high-rise buildings," Defence official Steven Grzeskowiak said on Wednesday.

"They're not buildings that people live in, they're not buildings that people would be asleep in overnight."

The buildings have since between fitted with fire-proof awnings as Defence works to replace the cladding by the end of the year.

Defence officials suggested people working in the buildings had been informed of the risk and were practising fire escapes more regularly than others, but could not say when the personnel were told.

Industry Minister Karen Andrews, who has responsibility for cladding and building codes, has claimed rectification works are under way across the five sites.

But Defence officials could not confirm whether this was the case, taking questions about the progress on notice.

FIVE NON-COMPLIANT BUILDINGS:

* HMAS Penguin, Sydney

* HMAS Cairns

* RAAF Townsville

* Fishermans Bend laboratories, Melbourne

* RAAF Edinburgh, Adelaide

Australian Associated Press