Yes, we renovated a commercial pool at Woodcroft Country Club in North Carolina. The equipment was located underground, including giant filters! We had to cut out all the plumbing due to the tight fit. It was a full day's work, but we completed the job before opening day, with the climbing water wall and children’s splash pad up and running, and the tile finished.

What's the most important thing people should know before they decide to rehab their pool?

It's important to be aware that there might be underlying issues that require additional repairs and potentially increase the overall cost of the project. Water can and will flow where and when it desires to flow. The styrofoam shown here became like a sponge, so we removed it. yes, you can use it to level your deck/ nose of the pool/ coping, but this is what happens over time. it starts growing and pushing out the tile or Plaster/pebble tech. 

We also noticed water flowing into the pool from the deck on a rain day. This should never be.

"know how water flows."

See picture below

Here we are getting ready to set tile. first we have to carefully cut out the pebble tech(plaster), then we will carefully chip it away. During this process we encountered something I have never seen before. There was Styrofoam placed behind the Plaster. 

This pool was built 35 years ago. I guess that's how they rolled.?? (Scratches head)

yes this is a added cost. We will remove all the foam and properly fix it.

This was the reason our clients plaster cracked under the nose of the pool.

only SOLUTIONS.