The testing of bunkers needs to be a top priority as sales grow, but no building can be made fireproof, the Victorian Bushfires Royal Commission has been told.

The royal commission last week began the second block of hearings examining building standards.

Housing Industry Association National Manager Codes and Standards Michael Harding told the royal commission that bunkers can’t be deemed safe until proper testing has taken place. Ventilation and access in particular need to be explored.

He says building regulations for homes in bushfire-prone areas only slow the rate that buildings burn – they don’t completely fireproof them.

Earlier in the week Victorian Building Commissioner Tony Arnel called for bunkers to be mandatory in high-risk bushfire prone areas. But a Kinglake survivor told the royal commission better building standards would do nothing to save lives in fires as severe as those experienced on February 7.

She described sprinklers fitted to her house as “like throwing a teaspoon of water onto a bonfire”.