Thicker Plaster to bring up Baja Shelf??

[DougS78]

First time posting, but have read across these forums as we build a new pool.

We are building a gunnite pool with a perimeter overflow edge surround. Gunite is fully in and now tile are set (establishing the water line). To cut to the chase, the baja shelf and a swimout bench are significantly deeper than we anticipated. Baja Shelf is 20.25" and swimout bench is ~25" meaning they can't be used for their respective purposes. Pool builder has offered to fix that their expense with extra plaster.

Specifically adding 2-3 inches of hydrazzo plaster to the baja shelf to bring it up to 18" which will allow us to have ledge loungers that won't float away. The question is if this is going to cause problems to have plaster so thick. Pool Company owner says it will be fine, although site foreman is unsure, which doesn't inspire confidence. The swimout bench would get some concrete parge and then plaster to bring to ~20"

I have searched online and can't locate anything about thickness of plaster other than what is typical. Is this sort of application going to work or is this asking for trouble?

Thanks for any input!

 

[ajw22]

Welcome to TFP.

I would rather they put a 3" layer of cement on the shelf to raise it before the plaster is applied.

@onBalance what are your thoughts on plaster being 3 inches thick?

 

[onBalance]

Having 3 inches of plaster is fine and completely acceptable.
Gunite (shotcrete) contains Portland cement, as does concrete, and pool plaster which contains the most cement.

 

[DougS78]

Thank you, these opinions are extremely helpful. Very glad to hear that a few extra inches of plaster is a reasonable solution from a design perspective.

Additional gunite was another option, but the pool builder was not willing to accept any of that cost, so its significantly more for us AND it means more delay to implement. Thus, the plaster is an easier solution and hopefully gets us in the water sooner. We also were told that with gunite adding only 3 inches would not be sufficient so it would become a 1st step depth on the ledge (which is shallower than we wanted and creates some potential plumbing issues). Thus, I'm quite happy to hear that this proposed solution sounds reasonable.

 

[DougS78]

Out of curiosity is there an amount of plaster where it would give you pause? As in "3 inches is fine, but would never go more than 5 inches" or something along those lines.

 

[onBalance]

Nope. Some pools have solid concrete for the shell. Gunite is different, but both are acceptable for a pool.

 

[DougS78]

Nope. Some pools have solid concrete for the shell. Gunite is different, but both are acceptable for a pool.

Thank you again for this expert opinion @onBalance !

As one follow up, is there is a difference in the application when Hydrazzo is applied in additional thickness?

I note that on the manufacturer's application guide (http://www.aquavations.com/wp-content/uploads/2014/03/Hydrazzo-Product-Application-Sheet1.pdf) it indicates a thickness of 3/8 to 3/4" and suggests that: "Material that is too thick (over ¾") is not effectively troweled unless it is layered."

So is the key that it be applied (troweled?) in successive layers?

We want to be sure we know what we are agreeing to if we select this fix from our pool builder. Thanks again!

 

[onBalance]

I have never heard of that concept, and it doesn't make sense. In my opinion, creating layers of plaster can result in bonding/delamination problems. The thickness of concrete driveways can range from 3 inches to a foot or more.