I don’t know anything about borrowing power but do you know about mortgage lenders insurance. If you have less than a 20% deposit (or if you are borrowing more than 80% of what the home is worth), your bank (or whatever) requires you to pay for mortgage lenders insurance. It not insurance for you, it’s insurance for them – if you default on your loan they are insured. But get this, they will lend you the money to buy the insurance so then you need to borrow more money and then you need to buy more insurance, so it does this crazy compounding thing.

ETA: M2OSB, I'm pretty sure you need a 20% deposit to avoid mortgage lenders insurance.