How do I lay out replacement stringers for angled wrap-around steps?

The math on a 45-degree corner stringer is just hip rafter geometry. Your unit rise stays identical to the common stringers—if you settled on a 7-inch rise, that doesn't change at all. For the run, multiply your standard tread run by 1.414. If your normal stringers have a 10.5-inch run, your corner stringer needs a 14.85-inch run (basically 14-7/8 inches). Just set your framing square with the normal rise on the tongue and that adjusted run on the body to step it out. Always double that diagonal stringer. A single 2x12 gets notoriously bouncy across that longer hip span, especially once you notch out the meat of the board. Doubling it up also gives you a full 3 inches of bearing surface, which saves you a massive headache when landing your tread and riser miters instead of trying to catch a 3/4-inch edge on a single board. To keep those riser miters tight, cut a 45-degree **backer block** out of scrap framing and mount it flush inside the corner between your doubled stringers. Put exterior polyurethane adhesive on the miter, pin the miters to each other, and screw through the risers right into that backer block. If you just face-nail them into the cut stringer edges, the seasonal humidity swings near that hot tub will gap them open within six months. Also, make sure you don't bury the stringer feet back in the dirt. Even ground-contact lumber turns to mush when it sits directly in wet soil under a splash zone. Pour a quick concrete pad or lay down a compacted gravel base topped with solid concrete patio pavers, then use standoff brackets to keep the end grain up out of the moisture. Run joist tape across every horizontal cut on those stringers before the treads go on, too.

definitly double that hip, but hit every single fresh cut with copper naphthenate or end-cut preservative before you stick that joist tape down. People forget that modern PT treatment only penetrates a quarter-inch into a 2x12. Once you cut those stair notches, you're exposing completly raw heartwood right in the hot tub splash zone. Taping is great, but sealing that bare grain first is what really keeps it from turning back into compost in five years.

This stair math is wild to see broken down, calculating hips always felt like pure wizardry! Quick side question though—since you have the whole thing gutted right by the tub, are you planning to add low-voltage deck lights into those risers? I'm building my very first deck this summer and am obsessed with the idea of step lighting, but how do people usually route the wiring through doubled stringers without weakening them? Do you just bore small holes through the center before slapping the treads on?

Watch your stringer spacing if you're running composite or PVC treads across that 45. Most manufacturers like TimberTech or Trex Transcend spec an 8-inch or 9-inch on-center max when boards run on a diagonal. If you try to maintain standard 12 or 16-inch stringer bays thru the radius, those mitered ends will cup and feel like a diving board by August.

Also, when securing that doubled hip to the rim, ditch 16d nails and drive three 5-inch FastenMaster TimberLOKs or Simpson SDWS screws through the landing rim straight into the meat of each 2x12 ply. Zero squeaks and it won't pull loose under heavy foot traffic.

One thing that saved my bacon when I rebuilt mine: cut your angled tread pieces out of cardboard or cheap scrap 1x first before touching the real decking.

Even if your framing math is spot-on, lumber is never perfectly straight, and my "45" ended up closer to 46.5 degrees once the stringers were lagged in. Making a physical template kept me from ruining expensive boards on bad miter cuts. Also, put some construction adhesive or exterior glue right in that tread miter seam too. Treads flex alot when people stomp down the stairs, and gluing that joint together keeps the boards from rubbing and squeaking against each other later on.