Beattie Varley Limited was called in to carry out a review.
Mr Varley found it was all above board, and some checks had simply "slipped through the cracks" in a situation he described as a "perfect storm" of mounting pressures.
In a statement, council chief executive Garry Poole said the quality of Holmes Farsight's work was not in question. The review was needed to show why council processes were not followed and to ensure ratepayers could have confidence in the council.
"The report suggests that the breaches were due to people making assumptions that internal sign-off and checks had been done by others when they hadn't. it also shows that council needed urgent support to ensure it could undertake its duties as a Building Consent Authority, and Holmes Farsight provided that gap at short notice."