The Insurer(s) shall not be liable for
All costs rendered necessary by defect of material workmanship design plan or specification and should damage occur to any por of the Insured Property containing any of the said defects the costs of replacement or rectification which is hereby excluded is that costs which would have been incurred if replacement or rectification of the Inured Property had been put in hand immediately prior to the said damage
For the purpose of this policy and not merely this exclusion it is understood and agreed that any portion of the Insured Property shall not be regarded as damaged solely by virtue of the existence of any defect of material workmanship design plan or specification