Hi Matt,
I don’t know of any builders in Sydney, but we have been referred work from our local building inspector on several occasions, so I would suggest that if no-one can help with a referral that your mate rings a local building inspector and asks them for 2-3 names of good quality tradesman for the type of job he has. A building inspector would have inspected work from the best and worst of them so he can be assured he will avoid the contractors whose work is substandard.

Regards
Julie Fisher
Daryl Fisher Homes