How to design a verandah over a deck?

[Dangledorf]

I am designing a deck and verandah to go at the back of my house. The deck will be 9m wide x 4m deep. My backyard slopes, so the greatest height from the deck to the ground is 1.5m.

Deck bearers and joists will be MGP10 H3. Bearers 2x190x35, joists 190x45. Joist spacing 450mm for 19mm merbau decking boards.

The deck is to be cantilevered 600mm over the last row of posts/bearer.

My question is, can I attach the verandah posts to the perimeter frame of the deck (in-line with the handrail) if the deck is cantilevered? ie. the posts holding up the roof won't go all the way to ground. I have calculated that 3 posts for the verandah beam are required along the front of the deck.

Does adding a roof load to the deck change the maximum spans of the deck on its own? I couldn't find this information in any span tables I was able to find.

TIA.

[MitchellMc]

Welcome to the Bunnings Workshop community @Dangledorf. It's brilliant to have you join us, and many thanks for your question about designing a verandah.

When you’re dealing with an elevated deck and especially a cantilevered section, I’d strongly recommend engaging a professional to help with the calculations. The roof load can affect the overall structure, and you’ll need to ensure everything is structurally sound. If the roof is to be supported by the cantilever, it’s important to consult with an engineer to get their input on your plans.

Additionally, make sure to check with your local council regarding permits for your build. They may require plans that have been constructed or signed off by an engineer.

To answer your question: If the deck structure is designed to account for the additional load from the roof, then yes, you could likely have the posts attached to the cantilevered section. However, adding a roof load will absolutely affect the required calibre of timber for the deck structure, so an engineer’s advice will be vital to ensuring safety and stability.

Please let me know if you have any questions.

Mitchell