Question

Would adding steps to a pool affect it's volume? Would adding steps affect the amount of pool lining needed?

Answer 1

yes and yes:)

Answer 2

Would they both increase?

Answer 3

yep

Answer 4

The available *volume* of a pool will actually decrease if you add steps (inside the pool). The existing water will rise as some of the original volume is displaced by the steps but the available volume still goes down.

Adding steps inside the pool will increase the amount of lining required assuming the lining must also cover the steps.