The share of household income needed to pay off a home loan for a typical house in Sydney is near a ten-year high, new figures show, despite interest rates being at their lowest levels in decades.

Credit ratings agency Moody's on Monday highlighted the extent to which the city's price boom was pressuring home buyers to spend a greater share of their pay on their mortgage.

Australia's apartment prices will be flat to falling in 2017. Credit:Glenn Hunt

The research by Moody's analyst Natsumi Matsuda​ calculated how much a two-income household, with average incomes, needed to cover the monthly loan repayments on a median price house.

The ratio is a key measure of housing affordability, which is affected by both house prices and the cost of debt.