It was common ground that the defect was a latent defect which could not have been discovered on reasonable inspection. (newlawjournal.co.uk)
The landlord is responsible for dangerous conditions that the landlord knows about or should know about upon reasonable inspection. (getinjuryanswers.com)
A latent defect is a fault in the property that would not be easily detectable by reasonable inspection of the property, such as a serious crack in the foundation that has been covered over with paneling or improper wiring covered by drywall. (nsrec.ns.ca)