What is under the vinyl liner of an inground swimming pool?

The materials under a vinyl liner in an inground swimming pool vary depending on the pool's construction method and the installer's preferences. Here are some common layers found beneath the vinyl liner:

1. Concrete: In many inground vinyl-lined pools, a concrete shell forms the primary structure. The concrete provides a solid base for the vinyl liner and helps retain water pressure.

2. Rebar (steel reinforcement): To strengthen the concrete structure, steel reinforcement bars (rebar) are typically embedded within the concrete. The rebar helps prevent cracking and increases the pool's overall durability.

3. Pool insulation: Several types of insulation can be installed beneath the vinyl liner to help maintain the pool's water temperature and reduce heat loss. Common insulation materials include foam board, spray foam, or other insulating products.

4. Pad: Beneath the insulation (if used), a layer of sand or a cushioning material, such as geotextile fabric, is sometimes installed to provide a soft base for the liner and protect it from damage caused by sharp objects or debris.

5. Water: Of course, water fills the pool once the vinyl liner is installed and sealed.

It's essential to follow industry standards and local building codes when constructing or renovating an inground swimming pool. A qualified pool professional can advise on the best materials and methods for installing a vinyl liner and ensure the pool's structural integrity and safety.