What a pisstake. What kind of priCk landlord would knowingly let someone live in their place with no roof insulation?!
Best to get it sprayfoamed. If you did it yourself op, would be few hundred not into thousands , but that’s not the point really ...
The property was built in the 90’s. A time when 50mm aero board went under concrete slabs. Now a days it’s 125-150mm.
Regulations change and improve.
The same people giving out about these crap regs are the same people giving out that force new builds to comply with the much higher current regs. Can’t win.