How to build roof over deck?

Question

I have a deck around 4.2m x 2.8m that i have installed with your advice and now need advice on timber size/choice to install a roof to cover

I'm thinking 2x 190x32mm facia boards and then three in between? Same size or 190x45mm (x3 lengths)? One 2.8m end board same dimensions to fix to.

With 90x45mm pine battens inbetween rafters?

Any help would be great 😊 thanks

EricL · Answer

Hello @SparkyStu

Adding a roof to an existing home is considered major structural building work, so you will usually need council approval and a building permit before construction starts. Depending on your local council and the scope of the project, this may involve a Development Application, Complying Development Certificate, or Construction Certificate. Because the work changes the structure of the home, it must comply with the National Construction Code, Australian Standards, wind ratings, waterproofing requirements, and local regulations such as bushfire or cyclone standards. Engineering drawings are often required to confirm the existing walls and footings can safely support the additional roof load.

Although owner-builder permits are available in some states, roofing work is one of the areas where using a licensed builder is strongly recommended. A roof is a critical structural and weatherproofing system, not just an external covering. Incorrect installation can lead to serious problems such as leaks, poor drainage, structural movement, mould, insulation issues, or roof failure during severe weather. Builders coordinate engineers, certifiers, roof plumbers, and inspections to ensure every stage meets legal and safety requirements.

DIY roofing is heavily restricted because of the risks involved. Roof work has strict safety regulations due to fall hazards and temporary structural instability during construction. In many cases, parts of the work such as structural framing, flashing, and roof plumbing must legally be completed by licensed tradespeople. Non-compliant DIY work can also create problems with insurance claims, property sales, and future renovations if approvals or certifications are missing.

I propose engaging the services of a qualified builder as it generally makes the process much smoother and provides confidence that the roof has been designed and installed correctly. A builder can manage approvals, engineering, materials, inspections, and certified trades while ensuring the new roof integrates properly with the existing home. It also gives you warranty protection and peace of mind that the work will remain safe, compliant, and durable long term.

If you have any other questions we can help with, please let us know.

Eric