More than 900 sales branches will be taking part in the UK's 'largest open house weekend' later this week.
The event, which is organised by Countrywide, sees vendors make their homes available for viewings, with buyers encouraged to make visits to multiple properties.
Countrywide says the event is supported by a nationwide campaign, with featured properties benefitting from enhanced exposure.
Last year, the event featured 11,500 properties and generated 24,500 viewings, resulting in almost 3,000 sales, according to Countrywide.
"The open house weekend allows sellers to truly promote their property to the widest possible audience and our branches will be open over the full weekend to maximise buyer enquiries," said a Countrywide spokesperson.
Strutt & Parker will be holding a similar event in October. Its previous national open house day took place in February, generating around 1,100 viewings, resulting in 32 sales.
Last month, high-end estate agency Hanover Private Office claimed that open house viewings are no longer effective at the top end of the market.
The firm's founder and managing director, Alex Newall, said that High Net Worth Individuals are not prepared to mingle with their competition and that even buying agents are failing to attend the events.