Advice on deck structure around a spa please.

[Loki429]

Hi

I'm after a bit of advice on how to create the deck support structure around a spa if anyone has any suggestions please.
See the attached pic for details.
The spa will sit on the ground, with the top sitting just above the deck level. (ie the deck will not have to support the spa.)
The spa does however sit right where a beam would have run the length of the deck.

How can I support the joists around the cutout for the spa?
Can I run a "mini beam" between the full length joists on either side of the spa and use that to support the shortened joists? I have drawn these in my attached pic.
Do I need to put in extra posts? One near each corner of the spa?
All relevant dimensions are on the pic. Spa is approx 2m square. Height above ground level at that end of the deck is approx 1.2m.

Many thanks!

[bionicbeatboy]

I did a similar thing around my kids sunken sand pit.

However i used the "I have no idea" approach and just put timber all the way around the lip of the sandpit so the ends of the boards were sitting on something. Then I put like your "mini beam" between the two outside joists.

The kids haven't fallen to their deaths yet!

However, my joists were over engineered by about 100% so the two outside joists have no trouble taking the wobble out of the cut one.

[joe greiner]

I suggest putting a post at the outboard end of each of the joists running next to the spa, similar to the pattern you've shown on the middle beam. This will reduce weird flexural behaviour of the deck. Might be best to double the joists alongside the spa, generously nailed together, or at least bolted together near the mini-beam's attachments.

The short joists spanning from the ledger to the mini-beam, and from the outboard beam and the other mini-beam can be stopped at the mini-beams. Put the mini-beams as close to the spa as possible. Use the same depth timbers for all of these components, using joist hangers for attachments. The way you've shown would have the mini-beams suspended from the joists alongside the spa; that will work too.

Verify your timber sizes for your spans and loads. Building code and/or one of the local brethren can advise on Oz requirements.

Joe

[patty]

Mate I saw an episode on back yard blitz once where they had the sunken spa tub thing in the deck an gee it looked like alot of work I think you can get onto their website still for some pointers

Scotty cam is the man

[Yonnee]

I would do just as you're thinking with a short bearer running either side of the spa.

I would be careful as to the spacings you're running of the bearers & stumps, because of bounce.
Also, when I was doing mine, my builder mate advised me to either put the bearers on top of the stumps, or make a small check-out at the top of the stump that the bearer can sit on so that you're not relying on just the bolt to support the entire deck. Imagine the dramas if the bolt gives way with a few people on the deck and the stump punches through the deck floor.