Redevelopment schemes in London that would result in the demolition of social housing will only get city hall funding if existing residents approve the scheme in a ballot, it has been announced, following a spate of controversial rebuilding programmes.

However, the measure announced on Wednesday by the London mayor, Sadiq Khan, will not apply retrospectively, meaning it will have no impact on some hugely contentious plans by London councils to raze existing estates.

A combination of soaring rents and house prices and cuts to council funding have seen local authorities in the capital seek to knock down older estates, sometimes building private homes alongside new social rented ones to boost funds.

The mayoral housing budget can contribute millions of pounds towards such schemes. Under the new plan, which was heavily backed in a consultation, this can only be received if the scheme is supported in an independently run ballot by all existing residents aged 16 or over.

The condition – billed as the first of its kind in the country – comes into force immediately. Khan has also urged councils and housing associations in London to carry out such ballots even if they are not seeking mayoral regeneration funding.

Two planned schemes in Westminster will now require such ballots to receive promised funding.

One, on the Ebury Bridge estate in Pimlico, will require a ballot even though the council polled residents in 2013, as the scheme has since changed, to involve the demolition of more affordable homes.

Another proposed regeneration, for the Church Street estate in Edgware Road, will only receive the planned £23.5m in mayoral funding if a ballot is held.

However, other projects already in place will not be affected, including two highly controversial schemes proposed by Lambeth council in south London.

A number of residents of Cressingham Gardens in Tulse Hill have been fighting a long battle against the planned razing of their 1960s estate, and have run their own poll, which the campaigners say shows a majority of people do not want the scheme to go ahead.

Ahead of the local elections in May, the Greens held their national campaign launch on the Central Hill estate in Crystal Palace, highlighting what the party said was opposition to Lambeth’s regeneration plans.

Khan said: “When estate regeneration is done well, it can improve the lives of existing residents as well as building more social housing. But that has not always been the case.

“Anyone drawing up plans for estate regeneration must involve local people and must consider what impact their plans will have on people who live there now.”