How to build a deck

[brelms]

Hi, I have yet another decking question.

when looking at the videos and reading these posts on building decks,  the timbers appear quite small.

The "How to build a deck" videos show what appears to be 45 x 90 laminated together as bearers and then 45 x 90 as joists (apart from the wall plate which looks to be more like a 140 x 45) .  but if i look under our current verandah and the recent extension which the deck will come off, then the builder has used laminated 140 x 45 as bearers and 140 x 45 as joists on brick pillars. The height off the ground is 250mm to 900 mm over a length of 12m. joists are spaced at 400mm and the supports for the bearers are at 1500. 

I also note the video shows concrete posts with threaded bolts at the top. I was proposing to use treated pine and stirrup cups

what would you suggest

thanks

brian

[Jason]

Welcome to the Bunnings Workshop community @brelms. We are really pleased to have you with us and look forward to seeing your decking project come together. Don't hesitate to post whenever you need a hand as we have helpful members sharing advice and inspiration on the site every day. 

Let me tag some knowledgable members to assist you: @Adam_W, @bruce93, @Brad and @Neo19. The wonderful @MitchellMc will also be happy to give you a hand when he is back on the site on Friday. 

Please let me know if you ever need help getting the most from the site, or have any feedback about how we can make Workshop even more useful to you.

Jason

[MitchellMc]

Hi @brelms,

I apologise for the delay in my reply. How are you going with your decking project?

In answer to your question, a decks structure which includes the bearers needs to be in compliance with relevant timber span tables and the Building Code of Australia. These are minimum requirements for building a deck and it is the decision of the person constructing the deck if they would like to over-engineer the structure. 

If the support for the bearers are at 1500mm then it sounds like two laminated 140 x 45mm timbers would be substantially larger than what is needed. I would encourage you to have a look at some span tables as you'll see a single 140 x 45mm timber is closer to what is needed to span 1500mm. A single 140 x 45mm timber would have roughly the same weight-bearing characteristics and span as two laminated 90 x 45mm timbers.

Treated pine posts and stirrups cups are more than adequate for use as supports unless there is some requirement from your local council to use concrete posts. We've used the concrete posts in our tutorial as they are a quick and effective way of creating supports.

Please let me know if you need further information or had questions.

Mitchell