We want to borrow about $300,000 for renovations. Do we have to have a contract with a builder or can we manage the process ourselves?

Hi Justin, $300,000 is a decent amount so more than likely your bank will want a contract which protects both you & them from over-runs, although it also depends on your situation/value of house/how much you're looking to borrow, as you may be able to get away with just organising a line of credit that you can draw as & when you need, ie. if the house is worth say $1.5m now & your total borrowings including the extra $300,000 is only say $1m then a line of credit will probably work if you can show serviceability, but if you will be reliant upon the increased value after the renos to secure the increased loan, then you probably won't get as much flexibility. Cheers

Short answer Justin is Yes, you can manage the process yourself.
The longer answer is "depends".
You would realistically need to show that you have the ability to manage the job, be able to produce an accurate costing for the job (gather quotes from all trades involved) and have a reasonable equity in the home.
Then there is the question of being treated as an owner builder (check this out to see if required), and finally insurance.
If you do not have a building/trade background, I suggest that it is not worth the headache to do this sort of thing yourself.
It looks easy on TV, but the reality is vastly different.
You go to a doctor if you are sick, a dentist if you have a toothache etc.
My advice would be to get a professional builder in to do the work.