As you are probably finding out, the LABC Warranty does not provide cover against every defect. As an insurance policy it gives cover for new home buyers against specified risks such as structural defects that can be costly to rectify.
As LABC state: their warranty "does not provide cover for general wear and tear, condensation, shrinkage, and damage arising from failure to maintain the property. For full details you should read your copy of the policy document that specifies the cover provided."
You should have received this from your solicitor when you legally completed.
If you did not or your solicitor did not ensure the new hame had a valid warranty he has been negligent.