Indoor pool DIY build in a barn

[tsf]

I'm moving house and leaving my outdoor "Endless Pool" which I love. The upside is our new place has a barn (15mx9mx5m) that I intend to convert to an indoor pool space, with a 12m pool and swim motor.

I'm hoping to do a lot of the work myself with occasional subcontracting. I see the project as an enjoyable learning experience (for now..) and don't want to outsouce to a main contractor. I will employ an architect and structual engineer to help with some of the bigger general construction decisions. BUT, I am keen to grasp and control the general direction of the project before involving those professionals.

The barn is a standard "agricultural" barn; a steel portal frame with reinforced concreate slab. It requires a complete "habitation" project before even starting the pool project. But both projects have to be considered now and thought about together.

A few thoughts:

1.I am expecting to heat the pool through a combination of under-floor/ambient & solar direct loop. The room will be heated with underfloor loops. My goal is for the entire project to be powered by renewable energy from local solar and ground source. (I may bolt in an electric heater if I need to heat up in a hurry, but the goal is that it is not required)

2. The Barn space lends itself well to an "above-ground" pool installation surrounded by raised flooring.

3. I am currently invesigating a total timber-based construction. Self-build is a big part of this project an I am most confortable with timber and I'm pretty sure it will be the most cost effective.

4. I have experience building modular vinyl pools (like my Endless Pool). So I am considering a pool like the one attached (The wooden frame will not be visible): https://www.dropbox.com/s/4nfyi85zqwh0n ... .jpeg?dl=0

QUESTION

So, what do you think of this construction cross section I have come up with below?

https://www.dropbox.com/s/5aa5h123kyksx ... n.png?dl=0

As I say, I will be working with architect and structural engineer. But, before engaging with them, I would like to be pretty clear what methodology I want.

Can I get away with this timber construction, or am I kidding myself not getting a slab under the pool?