Storm water pipe built into the wall

There is a litany of non compliant building practices that have caused structural damage to the timber framing and internal walls of this owner built enclosure.
Firstly bricking in down pipes in the cavity of the internal walls is totally counter productive as there is no avenue for maintenance or repair within the cavity wall.
The old galvanized down pipes are prone to corrosion and leaking.
Two down pipes have been directed into one with a poorly constructed join that has been leaking for a long time causing decay to the internal timber frame wall and plasterboard finishes and staining to the external brick work.
This whole area will require re building so that the storm water system can be re directed externally and made compliant.
Our building inspector often finds non compliant work when carrying out his building inspections and is then able to make his client aware of the defects.
It is very important for our clients to be fully informed of the condition and defects of their property before purchase.