At least 350,000 households will be excluded from the housing market by 2020 because of a lack of affordable homes to rent or buy, according to a new report.

The figures, which were published as property website Rightmove reported the smallest November slowdown in asking prices in four years, underline how the rising cost of all private sector housing is locking out those on low and middle incomes.

Analysis by property firm Savills shows that, over the next five years, 70,000 new households a year will be unable to afford to rent or buy homes at a market rate unless assisted in some way. This means that 350,000 will need some form of housing priced at below market rate by 2020, the firm said.

The figures use current incomes and prices for buying and renting and assume a household can pay up to 30% of its gross income on housing. They do not include “any backlog of unmet need and the effect of falling stock levels due to right to buy and proposed sale of high-value council homes,” Savills said, which suggests the impact of rising prices could be even more severe