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A lot of the times is it just purely preference. However, keep in mind when wrapping a tub on 3 sides. If there is ever a potential leak from the backside or even sides of the tub that may need to be repaired later on down the line, the tub would have to be moved to gain access.On a user standpoint- I suggest building the deck about 18 inches up the side-or halfway. Because, you can use it as a step. It is rather hard the older we get to step up out of a box of hot water that is sunk into a deck. Where if you had it only halfway, it's like using the deck and seats as a built in step to get in and out. (Sit on the side of the tub and swing in and out) Typically, I also recommend building the deck around the tub. BECAUSE what if your builder is not square? A half inch off? If the tub doesn't fit, what do you do then? It's a lot easier to build around something already in place, then it is to place something after you build. My two cents.
Wow! Great replies and ideas! This makes me think hard, and will definitely consider only sinking it half-way in. I still have a coup,e questions related to that. :1. There are not handles on the side of the tub. How do installers lower it into the hole whether it is half-way or all the way sunken in?2. If it is sunken all the way in, I can take off the access panel from the open side of the deck from underneath the deck. If it is half-way in, how do I get the panel off? It will be up against the deck boards instead of below the deck boards. Thanks!Tubby