Boundary question

The house next door to my parents' one is being knocked down to make way for a new development of apartments and small houses. Well, it's already been knocked to rubble actually. Now, the boundary between the two sites is delineated by a brick wall in front and a ditch with fencing on top in the back. It's a fairly wobbly line and I assume the builders will want a more solid barrier between the new development and my parents' house. My question is, would they have to come and make arrangements with my parents if they want to demolish the existing barriers? Or will we just walk outside one day and find the whole thing gone, without any advance warning? How does that sort of thing work?

(Yeah, I know it's a weird question - not even sure if this is the right forum tbh)

Thanks!