Where damage is caused to a visitor by a danger due to the faulty execution of any work of construction, maintenance or repair by an independent contractor, the occupier is not to be treated without more as answerable for the danger if in all the circumstances he had acted reasonably in entrusting the work to an independent contractor and had taken such steps, if any, as he reasonably ought in order to satisfy himself that the contractor was competent and that the work had been properly done.
I'm not a lawyer, but it seems to me to say that:
If you visit a place, and get hurt (e.g. by a chunk of ceiling falling on you or tripping on badly laid flooring), and it turns out that this is the fault of the contractor who built it, then the occupier will not be liable for your injuries as long as they acted reasonably to hire a good contractor and make sure the work was done right. This implies that if you can show that the occupier didn't do this then you can sue the occupier for damages, although the quoted text doesn't actually say so.