Vandals emptied two gallons of white paint onto the top floor of Piries Place car park in Horsham town centre over the weekend.
Decorators contracted to paint the buildings surrounding the top tier of the car park returned to work on Monday (June 2) to find paint smeared on the floor and walls, and empty cans.
Alex Kuharcsik, manager of SLK Decorators, said time that could have been spent painting had to be used to clean up the mess.
He said: “We came here in the morning with ten guys who want to work, and it is cleaning all day, and some of it won’t come off.
“We try to make the building nicer and somebody has just destroyed everything - it is crazy.”
Mr Kuharcsik said he believed the vandals had driven a vehicle over the paint on the car park, to spread the damage.
He said: “It is so hard to clean because you can’t use chemicals.
“I don’t understand people who do this, it is stupid.”
He added that the decorators may have to repaint over the vandalism on the car park floor and walls.
A Sussex Police spokesperson said: “On Sunday police were contacted by maintenance contractors at the Piries Place car park in Horsham, owned by Horsham District Council.
“The informant reported that cans of paint being used to decorate a stairwell and left on site had been opened and their contents scattered, causing damage which would need to be cleared up.”
Police are appealing for witnesses. Anyone with information can contact police on 101 or by sending an email to email@example.com, quoting serial 478 of 1/6.
Alternatively, you can contact the independent charity Crimestoppers anonymously on 0800 555111.