I'm doing an add-on for hardscape customer. We're expanding patio w/masonry garden wall to include an area for inground hottub. This will be my first one...plan on excavating to desired depth plus enough for concrete base w/drain and sump basin with pump. Surround will match existing masonry garden walls w/slate coping. I'll leave the masonry walls 2' outside width/length of hottub and fill in to edge of spa w/treated lumber grates (like in the bottom of saunas?) for water spillage/rain into the drain/sump area below. Finished height above grade will be around 12". Does that sound about right? This method seems preferable to burying an insulated shell...I'm wondering if anyone has built many of these and can offer some insights that might speed or ease my install? Thanks.