What spans and cantilever for deck?

Hi, I'm building a deck on the side of my house.

Plan is to bolt a ledger board to the concrete foundation and run joists out to 4200. Now my understanding of the span table says that if I use 190x45 joists I can span up to 3600. Here is where I'm uncertain, could I cantilever out to 4200 total if the bearer is at 3600?

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Comments

JacobZ

Hi @scotth,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

My understanding is that when joists are spaced at 450mm apart, a cantilever can be a maximum of 25% of the allowable span, provided the actual backspan is at least twice the actual cantilever.

Applied to your situation, this means the cantilever can be no more than 900mm, assuming the span between the bearers is at least 1800mm.

For the sake of safety, due to the complexity of having both a ledger board and a fairly decent-sized cantilever, I would suggest your design plans should be checked and okayed by a professional such as a draftsperson, builder or engineer prior to installation.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

scotth

https://www.workshop.bunnings.com.au/discussion/comment/55998#Comment_55998

Ok so 25% of the allowed span or 50% of the actual span, whichever is the lesser.

I've got a friend of a friend who's a builder I should be able to coax around with a cartoon to give my plan the yay or nay.

Thanks mate 👍

JacobZ

https://www.workshop.bunnings.com.au/discussion/comment/90275#Comment_90275

Spot on @scotth.

Good luck, and don't forget to share some photos when things are complete. It would be great to see how everything turns out.

Jacob

scotth

been a long road but this is where I'm up to.

Decided not to do the cantilever after talking it over with a builder friend. The posts come through the deck surface and will form the fence around the tall side of the deck.

JacobZ

https://www.workshop.bunnings.com.au/discussion/comment/61459#Comment_61459

Hi @scotth,

That deck looks brilliant!

I love that you've incorporated the three tiers to tie it in with the slope of the land and give you a really nice transition.

I'd say it was a wise decision to go without the cantilever, and I'm sure you have a much sturdier deck having done so.

Thank you for sharing. I hope you are happy with what you've achieved so far. I look forward to the next update when the fencing goes in.

Jacob

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