Here at SWConsult we frequently consult on structures suffering from leaks and cracks. This is often caused by poor Expansion Joints. Builders should understand that Expansion Joints effectively isolate different parts of the structure and the Expansion Joints generally require a movement capability of 15mm. This is substantial and poorly designed Expansion Joints lead to leaks and structural cracking plus waterproofing failure. If building Expansion Joints leak, particularly if Contractors have tried to fix, you probably need some professional advice.