Hi, I am building a narrow low level deck around a pool, and I am trying to work out the spans needed. I have looked through all the bunnings threads, including https://www.workshop.bunnings.com.au/t5/How-To/How-to-build-a-low-level-deck/ba-p/45715 but there isn't anywhere that provides the recommended span tables - and in relation to the structural type of wood bunnings sells (e.g. MPG).
Being of technical mind I find the span tables easy to follow, but ones that I find on the internet can vary greatly for even similar wood sizes and also vary depending on the structural classification of the wood. The wood I would like to use is the Bunnings 90X45 and 140X45 MPG H3.
The floor load width in many areas is 0.5m, as the deck is very narrow. The deck has lots of thing strips to go around a pool. Often the span tables don't have such small floor load widths. Using the lowest FLW available the number of bearer supports is getting rediculous, and then needing a mind boggling amount of concrete if one follows the specs for foundations. This is resulting in more concrete per area than the slab for the house. It is getting silly!
In summary, please provide the span tables bunnings recommends.
Thank you for sharing your question about low-level deck span design. Would it be possible to post a photo of the area and the proposed size you intend to make the low-level deck? This will give us a better idea of the location and allow us to give you an informed recommendation.
Let me find out if Bunnings has a recommended span table to use. As soon as I have the information I will relay it to you.
Thanks for you reply, and also my delay in replying. I have attached some photos. I am building a narrow deck around the pool. It varies in width from 40cm to maybe 2m. If you take normal span tables they often have the minimum floor load width of 2200mm, when of course mine is more likely panning out to 1000mm FLW or tapers to more or less nothing. Also span table and deck designs tend to double up the bearers. Whereas I have costed that double-bearer strategy out and it is typically 30% more expensive. A good start would be to find span tables that provides floor load widths of say 1200mm (i.e. more small residential projects), and uses wood of dimensions and structural specification (e.g. MPG) that bunnings sells.
Thank you for posting those pictures. To answer your question in your last post about span tables, after checking several sources I'm so sorry but Bunnings does not have a recommended one. However, the store used to carry this reference The Australian Decks And Pergolas Construction Manual 7th Ed. It is no longer available for purchase in the store but is still available online.
I recommend seeking the services of a professional deck builder in order for the build to be signed off. I could recommend building a custom frame with multiple joists in line with the bearers to hold the weight. Put numerous footings to spread the weight to prevent the deck from shifting. However, my recommendations are not up to council standards. Having the professional deck builder covers you for council inspections and insurance claims especially around your swimming pool.
Let tag our experienced member @Adam_W for their advice.
We look forward to seeing your deck built.
Thanks for the advice and also handy booklet. I unfortunately have not got the funds for a professional to look at it. That would have been ideal. Also, this pool would not be allowed to be there if it was built now, the previous owners built it 20 years ago. I have just moved in. I will probably look at council rules, exempt development etc myself and work out a design that at least fits all these. How do I tag Adam?
Thank you for giving us an update. Let me tag @Adam_W so that they are made aware of your proposed deck project.
Please keep us updated, we look forward to seeing your deck project begin.