We are planning to build a decl for our patio, which is 9x4.5 meters in size. The floor is currently paves with interlocked brics. My question is: can I make the frame directly on the brick floor or do I need something beneath it?
Welcome to the Bunnings Workshop community. It's superb having you join us, and thank you for sharing your question about your deck.
The general rule is to have as much space as you can between the ground and the bottom of the decking frame. The more space you have the better the air circulation will be under your deck. Trapped moisture under your decking frame greatly reduces the life span of your deck because it rots the timber.
I suggest having a quick look at this guide - How to build a low-level deck by @Adam_W. This guide will give you excellent pointers on what you need to consider when planning a deck. Would it be possible for you to post pictures of your patio? This will give our members a chance to assess the area. We can then make recommendations on what footing you should use for your decking frame.