We just spoke about building standards, and the particular ones to consider here are the Building Code of Australia and Australian Standards AS/NZS 3500.3 – Plumbing and Drainage. These standards should be followed by all builders and roofing contractors, but also by anybody doing a DIY job. It might not affect you right now, but if you ever try to sell your home and building inspection uncovers some mistakes in this area, ignorance won’t be accepted as an excuse.
Like any building works that aren’t approved or up to code, you would need to fix the issue before selling, which is more time and money wasted. So, for those reasons, it’s usually best to hire a professional roofing contractor to assist with any guttering and downpipe installation.