The dilapidated block on Worthing seafront, opposite the Dome, will be revitalised as part of a £90,000 makeover, due to open by June.
Part of the redevelopment will include a Changing Places disabled toilet – the first in Worthing town centre – after an online campaign led by a Goring mother raised £6,000 to contribute to the project.
Laura Moore, 37, of Ashurst Close, Goring, said: “This is an important addition to Worthing Town Centre. As a parent of a disabled boy, I’m acutely aware that it’s often very difficult to find suitable changing facilities when out and about, and this means that we often have to cut trips to town short.
“Having this Changing Places public toilet in the town will give the families and carers of those who need some extra support a suitable place for their needs, allowing them to enjoy the town for longer.”
Changing Places toilets differ to standard disabled toilets in that they include a changing bench, hoist, space for two carers and a privacy screen.
This allows more comfortable use for people with severe disabilities.
Pauline Fox, chief executive of Worthing Scope, which also contributed to the project, said: “People without complex mobility needs don’t always appreciate how difficult it can be to find somewhere appropriate to change or refresh oneself.
“We have seen how effective the Changing Places public toilets are in other areas of the country and are absolutely delighted to support the installation of this facility in Worthing.”
Councillor Clive Roberts, executive member for the environment, said he was pleased to get the project underway before the tourism season began.
He said: “The fact that local government has come together with a respected charity and a passionate local resident who developed an effective crowdfunding campaign is a genuine first within the Worthing Borough, if not beyond.
“I am so pleased that we are able to bring this much- needed resource to Worthing and to have it opened before the summer tourism season really begins in earnest.”
Building work, to be carried out by Kier Services, started on Monday.