If you’re thinking about building a gunite or shotcrete pool, you may have come across the term “rebound.” It’s a critical topic that isn’t discussed nearly enough, but it can make a significant difference in the durability and long-term performance of your pool.
What Is Rebound in Swimming Pool Construction?
When a pool is built with gunite or shotcrete, which is a type of concrete applied through a high-pressure hose, the process involves spraying the material against the pool form or rebar framework. In that process, some of the material “rebounds” or bounces back off the surface. This rebound material falls to the floor and may appear like the rest of the gunite or shotcrete, but it’s not.
The rebound was not hydrated correctly, making it a waste product. The rebound is weaker, less cohesive, and prone to cracking if used in the pool.
So, Can You Use Rebound in Pools?
The short answer? No, rebound should never be used in a structural part of the pool. However, reusing rebound compromises the structure’s strength and dramatically increases the risk of settling and cracking. Think of it like building a foundation out of scrap concrete — it might look okay at first, but over time, it won’t hold up.
Some pool builders attempt to save a few bucks by using it in steps, shelves, and benches, thinking it is acceptable to use it as filler material. Those features bear the weight of the water and people, possibly even more so because people frequently get in and out of the pool using them. The freeze–thaw cycle in the Treasure Valley affects the top 24” of the pool and will damage any of these features if rebound is used. Weak concrete in those areas can lead to expensive repairs down the road.
What Should Happen Instead?
A quality pool builder will remove all rebound from the pool. It should be discarded or used for non-structural purposes — never where structural integrity is required.
If you’re shopping around for a gunite pool, this is a question worth asking. A reputable builder won’t hesitate to explain their rebound practices. If someone tells you it’s “standard” to reuse rebound or brushes off your concern, that’s a red flag.
Summary
Rebound might look like regular concrete, but it doesn’t act like it. Using it in your pool structure is cutting corners, and your pool will ultimately pay the price in terms of durability and longevity.
If you’re investing in a gunite pool, make sure your builder follows best practices and doesn’t compromise your investment by reusing rebound.
And if you’re still deciding between gunite, vinyl, or fiberglass — keep in mind that fiberglass avoids this issue entirely and offers consistent strength throughout, which is just one more reason it’s gaining ground as the most reliable pool option, especially here in the Treasure Valley.