The new design standard for houses could mean that the number of houses being built in London could fall by more than 2,400, according to the London Development Agency (LDA).

The LDA last week published its updated version of the London Housing Design Guide, which will set standards for areas such as minimum size and bicycle parking provision.

Research carried out for the LDA by agent GVA Grimley, and published alongside the guide says the space requirements could lead to 2,430 fewer homes being built on existing sites every year, as a worst-case scenario. It said the guide, part of Mayor Boris Johnson’s crusade against “hobbit homes”, was “most likely” to mean between 240 and 1,220 fewer homes.

The research also found that these changes would add anything between 3% and 16% to the cost of building a new home, depending on the type of dwelling, apartment will be the worst affected. The study says the new standards will add £24,000 a unit.

This increase could be enough to make apartments uneconomic in some areas of the capital. “There will be many instances where the viability is sufficiently robust … to be able to afford the requirements. However, in a number of cases, especially those where sale values are less than the average for London, the initial impact may be significant.”

Meeting the standard will be mandatory for homes receiving social housing funding, beginning April 2011.

The guide goes back on some items in the 2009 draft, including that flats should have windows in more than one side, following protests from developers.

Tony Pidgley, the chairman of Berkeley Group, said the guide was “balanced” but that it did raise some viability concerns. “You need to spend £100m to get on site in London, so developers have to be allowed to offer a range of products,” he said.

The guide has been welcomed by architects; with the RIBA saying new standards were crucial.