Inset jacuzzi - height for dividing wall above waterline?

Hi guys, thanks for your responses. Here are some photos

Good questions kimkats!

My understanding of how they will add height is by building forms on the inside and outside of the existing wall, and pouring additional concrete and leveling off to the exact height that we need. The pool builder is pretty dialed on concrete issues so I'm not concerned about his methods in terms of addressing the cold joint; the whole area will be waterproofed afterwards as well.

As far as how we got here, we as homeowners have been trying to decide between a slope and flat-top wall since before, during, and after shotcrete day. The pool builder likes a sloped top, both for practical reasons (water runs off versus sitting on top) and aesthetic (when the span runs, it kind of makes the spa feel bigger, almost like an infinity edge). We like the flat top aesthetic better, and that's probably the predominant factor for us. But in addition, practically speaking, I know my kids will step and jump off all the time and it seems safer to have a flat top than a slope that could increase the potential for slipping. We hadn't thought ahead about this much, and on shotcrete day we didn't want to lock into one option. The wires guiding the shotcrete forming were set to have the lower corner at waterline level, so we flattened off at that level with a plan to build forms and re-set the height (or slope) as appropriate) later on.

And going back a couple of posts, I think the overflow is adjustable? But I'm not 100% sure on that. I was expecting that it would be set an inch or so above the nominal waterline. We are using 2x8 tile set vertically, so the waterline is going to be set at the midpoint - 4" down from top of tile. I would expect the overflow to kick in at 1-2" above that (suggestions welcome though).

I think I get the point of the question overall, though - it'd be dumb to have an overflow above the wall. If we did that, heavy rain or an overfill (if that can happen) would mean there'd be guaranteed spillover between the spa and pool.

So I checked, and we have the second type of overflow shown above. It's set to nominal waterline +1". So in theory we could make our spa wall +1.5" and we'd always have at minimum 0.5" out of the water, but more spillover. Or we could go with 1" and *if* the pool filled up to the overflow, it'd be right at the top of the wall. The pool builder suggests +2" just for less mixing from splashing, etc. between the spa and pool.

We like the look of a lower wall, less sticking out above the waterline, but we also want to consider issues of practicality and industry best practices.

AQUA~HOLICS said:

What type of finish are you planning on facing the top of the spa spillway?
Glazed tile that’s wet is going to be very difficult to walk over safely. If the spa wall is cut slightly away from the spa and raised 1/2” above the pool water level the tile will have the opportunity to dry.
Go with the look you want to achieve, the +2” will only help when both spa and pool are being used at the same time.

Click to expand...

We're using a 2x8 tile from www.fireclaytile.com. It says the tile has a DCOF of 0.42. That's probably lower when wet.

To be clear, I'm not going to encourage walking on the spa wall. I'm just trying to recognize that it will happen despite my best efforts, at least occasionally, and flat seems safer than sloped.

We are going with +1.5". That's above the +1" overflow setting and fingers crossed is the best balance between the look we want to achieve (lower to the waterline) and practicality in terms of preventing mixing of cold water into the spa and vice versa (which would be otherwise best served by a taller wall).