Gunite spa bench sounds hollow and has very rough looking surface

[poolguy968]

Hi folks, I am getting ready to plaster my new construction gunite pool/spa combo and I have some concerns because:

1. The gunite around the bottom of the spa benches is very rough and kind of crumbly looking. The main reason for this is because the benchs were actually created in two stages. On the day that the gunite company sprayed all the pool gunite, they accidentally made the spa benches too narrow. Then about a month later their worker came back and extended the width of all the benches by an additional one inch. They applied the additional gunite by hand. Now it looks really rough and I'm a bit concerned if any plaster added to this area may soon crack or not attach properly.
2. When I tap on the side of the spa benches with a hammer, I can hear a hollow sound that is very different from what I hear when I tap the gunite in the pool where it sounds solid/non-hollow.
3. I have these glass tile markers installed on the gunite benches that have not been grouted. I'm not sure if the pebble plaster can fully fill in the gaps/grout lines since they are quite thin or if I should get the tiles on the benches grouted before plaster?

I've attached some pictures of the gunite in my spa, especially around the benches. I'm especially concerned about the unevenness of the gunite and the hollow noise and I'm wondering if they may cause the plaster to crack or not stick? Do you guys think these issues require any additional steps to address? Or if it should be ok to just spray on the plaster without doing anything else?

 

[kimkats]

LOVE, LOVE, LOVE your tile! Do not grout it. They can and should use the plaster instead. That is what will look the best in the end.

Hollow sound-Ask the PB to come out and listen with you. Ask him to drill a hole into it to prove it is not hollow. Let us know what you find.

Roughness and uneven-all of that can be fixed with the plaster.

Crumbly concrete-can you easily scrape it off?

 

[poolguy968]

Thank you! It definitely took a while to pick put the tile but I'm pretty happy with it now!

I'm currently talking to the PB about checking the hollowness. He says he'll reach back out to the gunite company so I guess I'll have to wait to see what they say. Will keep you posted.

I actually went and inspected the "crumbly" part more closely and it's not actually
crumbling but just looks very rough. The PB also says that's ok so I guess hopefully everything will be fine.