Last year ended with average house prices up 1.4% over the 12 months, Nationwide has reported.
December’s average price of £215,282 was slightly down on the £215,734 that the lender reported for November.
Robert Gardner, Nationwide’s chief economist, said that this year he expects house prices to remain broadly flat.
He said that affordability would continue to be a problem for first-time buyers.
In London, he said, rapid house price growth in the three years to 2015 means that “monthly mortgage payments would be unaffordable for a large proportion of the local population”.
Outside London and the south-east, raising a deposit was the main challenge.
He said: “Even in the north and Scotland, where property appears most affordable, it would still take someone earning the average wage and saving 15% of their take-home pay each month more than five years to save a 20% deposit.
“In Wales and Northern Ireland, it would take prospective buyers nearly seven years, and almost eight years for people living in the west midlands.
“Reflecting the trend in overall house prices, the deposit challenge is most daunting in the south of England, where it would take an average earner almost a decade to amass a 20% deposit.
“Again, the pressures are most acute in the capital, where someone earning an average income would need around 15 years to save a 20% deposit on the typical London property.
“This is even longer than was the case before the financial crisis, when it would have taken around ten and a half years.”
Geographically last year, house prices rose most in Scotland and average prices went down most in London, with a 1.8% drop.