This appears to be largely down to rising mortgage rates, as cash sales are expected to fall by just one per cent, while mortgage sales plummet by almost a third (28 per cent).
New buy-to-let has also been squeezed by rising mortgage rates, with BTL mortgage purchases accounting for 8 per cent of sales each year.
As Zoopla explains, the typical buy-to-let buyer in the south of England needs to inject 40-50 per cent of the property's value as equity to make the numbers stack up, which isn't a good idea for below-base rate properties with gross rental yields of less than five per cent.
Sales of new three- and four-bedroom homes fell by 40 per cent in July compared to the same period over the past five years, while sales of smaller - and more affordable - homes fell by a smaller margin.
Mortgage rates have been falling in recent weeks, albeit slowly, but still by more than 5 per cent.
Zoopla says mortgage rates must fall below 5 per cent to improve affordability and stimulate more demand for home ownership.
With wages growing rapidly (up 7 per cent last year), affordability is improving relative to income.
With house prices falling modestly and average incomes growing, housing affordability in terms of house price to income ratio will improve by 9-10 per cent in 2023.
By the end of 2023, the UK house price to income ratio will be 6.3 times the 20-year average.
Surprisingly, the greatest improvement in affordability will be in London, where the house price to income ratio will reach single digits for the first time in 11 years as house price growth continues to lag behind income growth.