Swimming Pool Structural Collapse Due to Rain

How it Works

• Inground swimming pools are typically installed with a large quantity of backfill around them. The backfill supports the weight of the water and the pool walls or shell. If the pool edges are not sealed properly, rainwater enters and causes the sand in the backfill to liquefy and change position. When the backfill becomes saturated because of water passing through the substrate, it erodes. This causes the backfill to move, and the lack of support results in bulging walls and cracks in fiberglass pools, and the collapse of steel pool walls in vinyl pools.

Full Pool Collapse

• Once the pool walls and base are no longer supported adequately, the weight of the pool water could cause the fiberglass shell to bulge outward or the pool walls to crack and leak into the cavity, contributing further to the erosion. This becomes an ongoing problem that can end with the structural collapse of the pool.

Empty Pool Collapse

• A swimming pool needs to be at least half-full at all times, unless you are emptying it to change the lining or perform repairs. When half-full, if rain has entered the foundation of the pool, it can cause movement of the water through the substrate and inward pressure, known as negative hydrostatic pressure, against the pool shell. When the pool is less than completely full, it offers insufficient resistance to this pressure and the rainwater-logged foundation may cause the shell or walls to collapse.

Solution

• Once a swimming pool has a structural collapse, the only way to repair it is to rebuild the collapsed section. Drain the pool of as much water as possible, remove the damaged section, dry out the rainwater and rebuild it, ensuring adequate drainage and proper sealing. If your pool has steel walls and a concrete base, you can rebuild only the appropriate area. You can patch and repair minor cracks in a fiberglass shell, but if the damage is extensive, you may need to replace the entire shell.

Prevention

• Check your swimming pool structure and surrounds regularly for gaps where rain could enter the foundation. Seal any openings between the pool walls and the edges and shore up the dirt around the pool, packing it tightly to enable it to withstand any dampness without eroding. Eliminate any areas where rain could pool on the paving and seep into the foundation by building up a slight slope so the water can run off away from the pool and foundations.