Volunteers will sleep rough outside York Minster to help a charity for homeless young people as it faces a “worrying surge” in demand.

About 20 staff and volunteers hope to raise at least £2,000 for SASH (Safe and Sound Homes), which helps homeless young people in York and North Yorkshire by providing safe, temporary accommodation in volunteers’ homes.

The charity, which offered help to 120 homeless young people and provided 436 nights of accommodation last year, revealed demand in the first two months of this year was up by three quarters on the same period last year. Director Peter Robinson said it was a “worrying surge”.

Spokeswoman Clare Usher said SASH received 22 referrals in the two months last year, and 39 so far this year, and had offered 64 bed nights last year and 111 this year.

• Anyone wishing to support the event can sponsor participants using the Virgin Money Giving page at uk.virginmoneygiving.com/charities/safeandsoundhomes