How to build a DIY deck?

Builddeck

Hello, building a deck at my backyard, need some help on sub structure. Size of post, joist, bearear and also layout. Deck size I am looking to build is 12.5m wide and 4 m length. Please find the Image of the area. Thank you.

JacobZ

Hi @Builddeck,

Thank you for your post and welcome to the Bunnings Workshop community, it is great to have you join us.

Unfortunately, due to the size of the deck you're looking to build, you will require council approval for this deck to get built.

I'd suggest you start by contacting your local council so they can assist you with understanding your requirements in terms of planning.

It's likely that you will have to submit detailed building plans that are prepared by an engineer or draftsman. They will be able to assist you in designing the deck.

Frequently 100 x 100mm Hardwood Posts and 140x35 H3 Framing Pine are used as the posts and frame for a deck, but the choice of materials come down to the specific layout of the deck, so the draftsman or engineer who assist with the design will be the best person to tell you what specific materials you'll require.

It is also worth having a look at these Timber Span Tables from Hyne Timber which will give you an idea of common decking materials and the distance between support, either from a post or a bearer, that they can span.

Let me know if you have any further questions.

Jacob

Builddeck

Thanks for the response Jacob, I checked exempt lego NSW, if the land is 400m^2 you can build 60m^2 deck.

MitchellMc

That's super to hear, @Builddeck; it's always best to check with your council before starting such a significant build. Given this would be considered a large deck, if you haven't already, I'd encourage you to speak with your local council directly via phone just to make sure it doesn't need approval. Sometimes, there can be points that overrule others, such as It must not have an area of more than 25 square meters. I'd hate for you to build such a magnificent deck only to run into complications.

I've gone ahead and mocked up a sub-structure for you. It uses 90 x 45mm timber, the joists are spaced at 450mm centres, and they are supported every 1000mm.

Please let me know if you have any questions.

Mitchell

Builddeck

Thats great Mitchell,

I have changed the deck size, alsoattached the picture for your reference. Please give me detaip materials so that I can order online needed for structure. I will probabably go for marbau deck. Thank

you in advance.

MitchellMc

Hi @Builddeck,

It would be best to visit your local store once you've spent some time writing out a list of what you'll need. A team member can help you select the best timber for your project. Unfortunately, it's not as simple as me providing a list of materials, as since it's such a large deck, you'll need to work out where you will be placing joints and what length will have the least amount of wastage.

As a very rough approximation, 28 lengths of 90 x 45mm Outdoor Framing H3 Treated Pine - 4.2m, 79 footers or pedestal feet, and 380 metres of 90mm Merbau decking would get you most of the way there.

Mitchell