Businesses based in a "dilapidated" 1960s office block say moves to revamp it will leave them homeless.
Redrow Homes Ltd plans to refurbish Northway House in High Road, Whetstone, and develop the site for new homes as well as employment space.
But current tenants will be forced out of the 13-storey building while the refurbishment takes place.
Peter Williams, managing director of Elite Protection, said: “We’ve been tenants here for four years but it’s looking like we’re going to be homeless by July.
“We were told on Thursday they had some ideas for the building – these plans look pretty advanced. It would have been nice to have been told a bit earlier.
“We’ve just spent a considerable amount on IT equipment and telephone systems. Now we’re going to have to spend about £25,000 to 30,000 to move. We’ll have to sort out our business cards, telephones, emails – the costs will be huge.”
Mr Williams said if the plans go ahead, they will not return to Northway House.
People were invited to look at the proposals yesterday before a planning application is made to Barnet Borough Council early next year.
The plans will involve new cladding for the building as well as landscaping.
Philip Chadda, land director of Redrow Homes, said: “We feel this is a great opportunity to bring a dilapidated building back to life, and provide valuable homes and employment to local people.
“Current tenants will have to move out for health and safety reasons, but they can move back in.”
He cited Coffee and Tease, a coffee shop on the first floor, which also runs a nursery. Mr Chadda confirmed Redrow would like to retain this space for retail use.
Architect Chris Tapp added: “The building is already deteriorating. If these plans don’t go ahead, the building will only continue to deteriorate.”