By law, you have to insure your own and your share of the common property, so that if the tenement needs to be rebuilt you can contribute.
However, you are only properly insured if every other owner in the tenement is insured too.
Owners have the legal right to ask other owners to show evidence proving that they're fully insured to the full 'reinstatement value' (the cost of rebuilding the tenement), and all their premiums are fully paid.
You have to make this request in writing and the owner must give you the evidence within 14 days.
If an owner isn't properly insured, any other owner can go to the courts and ask them to force the owner to get proper insurance.