Long queues for the women's toilets could become a thing of the past if a proposal to force developers to provide more facilities in offices is approved.

The aim of a new British Standard is to increase toilet provision for women - the installation of urinals in men's toilets means that almost all offices have many more facilities for men than women.

Currently the number of toilets provided is determined by the building's floor area - the assumption being that there is one person for every 14 m2. The new standard will instead link toilet provision to the area devoted to fire escapes. As fire escapes assume a population density of one person for every 6 m², the net effect is hugely to increase the number of toilets that must be provided.

At present this version of the British Standard, BS 6465, is advisory, but it is likely it will be used to update Part G of the Building Regulations, in which case it will become compulsory.

The effect is that developers undertaking schemes at present are faced with a choice between cutting fire escape provision to below best practice, or sacrificing lettable area to fit in many more toilets.

Peter Caplehorn, technical director of architect Scott Brownrigg, said: "This effectively means a doubling of toilet numbers. On a commercial building it has an enormous effect on gross to net.

"Until it goes into Building Regulations we will explain the conundrum between fire and toilet provision and ask clients what they want to do."

Michelle Barkley, chair of the committee that drafted the standard, said: "There has been totally inadequate toilet provision as women normally have to queue for the loo and men don't."

Barkley said she had written to Ruth Kelly, who heads the Department for Communities and Local Government, to use the standard as guidance for the Equality Act 2006 it comes into force in April next year. "It could mean that councils won't give planning permission if buildings don't have adequate toilet provision," she said.