UK prime minister Theresa May has committed an extra £2 billion to building new affordable housing – but the figure is nowhere near high enough to solve the housing crisis, according to Royal British Institute of Architects president Ben Derbyshire.

Derbyshire, who took on the role of RIBA president last month, said that much more funding is necessary to undo years of under-investment in new housing.

"While it's good news that the prime minister has made fixing the housing crisis a central priority for the government, the extra £2 billion promised just won't meet the scale of investment needed to address decades of under-supply," said Derbyshire.

"The government spends billions of pounds a year subsidising private landlords because of a shortage of social housing," he continued. "They need to dial up the approach and investment, moving beyond describing the problems and big rhetoric to delivering solutions and the investment that will make the difference."

Conservatives will spend £9 billion on housing over two years

May announced the extra funding in a speech at the Conservative Party Conference in Manchester yesterday. The funding injection brings the government's total contribution to affordable housing construction to just shy of £9 billion over a two-year period.

The prime minister said councils and housing associations would be invited to bid for the money as part of a push towards "fixing our broken housing market".

"For 30 or 40 years we simply haven't built enough homes, and as a result the prices have risen so much that the average home now costs almost eight times average earnings. And that's been a disaster for young people in particular," said May.

"We will invest an addition £2 billion in affordable housing, taking the government's total affordable housing budget to almost £9 billion."

Government must invest more in social housing, says Derbyshire

Earlier this week, Derbyshire presented this year's RIBA Royal Gold Medal to architect Neave Brown, recognising the role he played in improving the standard of the UK's public housing.

He claims that major housebuilding programmes, like the ones Brown was involved in, are essential to tackle the crisis.

"Earlier this week the RIBA awarded Neave Brown the Royal Gold Medal, architecture's highest accolade, for his outstanding work in building high quality affordable housing, cherished by local communities," he said. "Social housing like this plays a vital role in ensuring that we have a society that works for everyone."

"Warm words won't put roofs over people's heads," he added. "We need a concerted programme of public investment in new social housing across the country and that means spending a lot more."

Ben Derbyshire took over the role of RIBA president from Jane Duncan in September 2017. A managing partner of design consultancy HTA Design, Derbyshire was elected to the role in August 2016.