Jul 24, 2018 8:27 pm
I am planning on building a deck over my alfresco. When I had the house built I asked for the slab to be one brick course lower, so I have a 155mm drop from the back door. More than many which is good.
The concrete slab is 4200w and 3100d and I intend going past the concrete by 500mm (to match the roof line) all around to make it 5200x3600 in total.
Over the concrete I plan to use 90x45 joists @440 centre spacing supported by 4 Kleva Klips per joist. This gives a maximum span of 1000mm (that is what Kelva Klip recommend, not sure why when a 90x45 joist can span 1600mm according to span tables).
I plan on having a picture frame border, so on the short sides I need a minimum of 2x90x45 joists with 90mm blocking between them spaced at 450mm. What I mean by that is I will have one full length joist, then 90mm of blocking then another full length joist.
If I was just going over the concrete I would be right, but extending beyond it means I have a few questions.
Firstly with joists on the outside, what do people suggest I use to best support them with? At 3600 long I gather I would be looking at 4 possibly 5 stirrups (I hate posts in the ground), but if I did that would I be better off using 3 full length timbers rather than 2 So would be full length, blocking, then 2 full length bonded together which in turn would have the stirrups bolted through?
As for the where the joists will overhang the slab at the end, I don't have enough space for a bearer, so what do I use to support them? Do they require a support of some type under each and every one (there would be 10 over hanging) or can I get away with supporting every second one and making sure I have noggins between the joists near the support to keep it tight? Plus of course a timber along the end of all the joists.
Lastly what is the thoughts on airflow under the deck? Seeing as it is mostly under cover do I really need to leave a gap around for airflow, provided of course everything is held up off the ground? And what are peoples thoughts on the plastic/rubbery joist protectors? Worth it, especially in the undercover section?
Re: Building Deck over Alfresco2
Jul 26, 2018 6:49 am
Try Putting up a sketch
Timber Deck here
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