What decking joists for under a spa?

[cansel]

Hi looking over Xmas to build a low level free standing deck approximately 2.4x3m which the ground varies in height by about 150mm. I am looking to place an inflatable spa approx 700litres on the far side which is highest from the ground. Will 90x45 timber be sufficient for that weight? I cannot really go any higher as the fence height then becomes an issue.

[EricL]

Hello @cansel 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about building a low-level deck for your spa.

In this particular situation, I suggest engaging the services of an engineer or drafts person. This will require precise engineering in regards to the number of posts necessary to hold the weight of the spa, the number of people standing on the spa and it has to take into the account the dynamic forces applied by the spa to the deck itself. 

However, in order to give yourself a head start, I suggest having a quick look at these guides - How to build a low-level deck by @Adam_W and How to build a deck by @MitchellMc. These guides will give you a general idea of what to take into consideration when planning a decking frame.

If you have any other questions we can help with, please let us know.

Eric