Tens of thousands of London homes have been left uninhabited for so long they are considered “long-term vacant” with more than 1,100 of them empty for over a decade, according to data obtained by the Guardian.

Despite a chronic shortage of housing in the capital, more than 22,000 homes have been left empty by their owners for longer than six months, data received from London boroughs in response to freedom of information requests has revealed.



Councils looking to bring vacant properties back into use have a range of options, including levying an additional rate of council tax, helping homeowners with the cost of repairs, or even compulsory purchase orders.



But the data shows that a large proportion of the homes have been empty for years rather than months, calling into question efforts to ensure existing housing stock does not go to waste.



More than a third of the total – 8,561 – have been left uninhabited for over two years, according to the data, with 1,151 empty for more than a decade.

Siân Berry, the Green party candidate for mayor of London, said: “With homelessness rising to crisis proportions it’s not right that so many properties should be sitting empty, and for so long.

“The best way of bringing them back into use is via self-help housing groups – in many cases building a constructive relationship with the owner, who may well not have wanted the property to fall into disuse in the first place and will welcome efforts to put matters right.”

The true number of empty homes could be even higher than the figures indicate. Homeowners are not obliged to report to the local council that their property is empty, and councils do not have to keep registers of empty homes. Council tax databases also do not include properties in such a state of disrepair that they are uninhabitable.



Also, the data comes from 31 of 33 London authorities who responded to the FoI request sent in October 2015. Bromley council did not respond, while Westminster said it could not supply the dates the properties became empty.

In addition, since April 2013 councils have been able to impose a punitive “empty homes premium” of an additional 50% council tax, disincentivising homeowners from admitting that they are leaving properties empty.

With the 3.4m homes in Greater London no longer sufficient for the capital’s growing population, some councils are beginning to take action against the phenomenon of “buy to leave”, whereby asset speculators buy homes with the intention of leaving them uninhabited so as to take maximum advantage of spiralling London property prices.



Last year, Islington council implemented planning laws aimed at banning owners of new homes from leaving the properties empty for longer than three months, with the threat of legal action for those flouting the ban.



Other reasons properties fall empty include owners not knowing what to do with inherited property, or lacking the funds to return damaged properties to a habitable state.



“With so many people priced out of decent housing across London, it makes sense to make the most of existing properties, as well as build new homes, to address the capital’s housing needs,” said Helen Williams, the chief executive of charity Empty Homes.



“The casework that councils do with property owners can be incredibly effective in ensuring that homes that have been stuck empty are brought back into use. At the same time, we would like to see more long-term empty properties across England bought by councils and charities to create new homes that are affordable to people on low to moderate incomes.



“But questions remain as to how well government-funded housing programmes will continue to support this work, now that dedicated empty homes programmes have come to an end”.