If you want to build your own deck for a hot tub, it's vital to have a good plan before you start building. If it's going to be an ornamental deck that won't have to support the weight of your hot tub, you have a lot of options. You can choose the materials and the only real safety concern will be to make sure it can support the weight of several adults standing and walking on it.
However, if you plan to build a hot tub deck that will totally support the hot tub, more care needs to be taken in the planning and execution. The first thing to take into consideration is the weight to be supported. Most hot tubs weigh 250-350 kg when empty, and the larger ones weigh close to 3.500 - 4.000 kg when filled with water and several adults.
So, the support system that underpins your deck will need to be strong and long-lasting. Check with a professional for the best plan for building a tub-supporting deck that will be completely safe and last for years. The basic idea to keep in mind is this: the bigger the deck, the more support posts you'll need in the center, so the weight of the full tub doesn't cause sagging and potential safety issues.
When planning your hot tub deck, think how it will really be used. If you know it will be used mainly by yourself and your partner, a small deck should suffice. If you're a 'no nonsense' hot tubber - you get in, stay in, then go back in the house - a deck that simply provides access to the tub is probably all you need.
On the other hand, if you plan to throw parties and have the maximum number of bodies in your hot tub on a regular basis, you need to give more thought to your deck plan. The deck will become the central focus for handing out drinks, accommodating the people who want to talk but don't want to get into your hot tub or can't fit inside it, and for haning all the towels and clothing that need to be within arm's reach.
If you take the time to think these issues through and even write it all down, you'll find that your plan for a hot tub deck will cover all the basics. It will definitely be much easier to build with confidence when the work actually starts.