Only a fraction of NSW residents living in bushfire zones have checked their insurance policies to make sure they have proper coverage since last year's devastating bushfire disaster.

As a result, some homeowners risk falling short by more than $100,000 if they lose their property in a blaze, a leading insurer claims.

Insurance company GIO says changes to building regulations to make homes more bushfire resilient could add up to 25 per cent to the rebuilding cost.

“Checking you have the right coverage is a must,” GIO spokesman Stephen Bell said.

“The new code means houses built in bushfire zones now have stringent construction and material requirements.”

In the wake of the Victorian bushfires in 2009, changes were made to national building standards for homes built in at risk areas.

According to results from a Newspoll survey carried out in February, Mr Bell claimed only 13 per cent of NSW residents in bushfire risk areas had ensured they had adequate coverage despite publicity from last year’s disaster in the Blue Mountains.

More than 200 homes were destroyed last October, most in the small village of Winmalee, when fires ripped through the region.

Many Blue Mountains residents are still grappling with blown-out rebuild costs after losing their homes.

Springwood resident Joe Moore had his family home insured for $500,000 before it burnt down in the fires.

He is now facing being left hundreds of thousands of dollars short after taking into account building regulations like double glazed windows and constructing in a flame zone.

Mr Moore, who cares for five foster children and has three sons, says he is not alone in deciding whether to rebuild or not.

“That’s why some people haven’t made their minds up because they are also under insured and had to downsize,” he told AAP recently.

GIO Insurance says its customers have lodged $60 million in claims since the fires with a majority coming out of the Blue Mountains.