Property speculators are converting cold, damp garages into so-called "utility rooms" where desperate families are sleeping - a practice investors say adds value but critics have described as "exploitation".

A Weekend Herald investigation found dozens of recent property listings where traders had lined and carpeted garages during renovation, some also adding walls to split the sheds into two.

Some were set up as a lounge and two bedrooms. Only one had a toilet in it - which did not have consent.

The spaces were marketed as utility rooms, not bedrooms, to avoid laws that define habitable spaces - laws which