The chalk lines on the floor mark the front edge of each riser. To use the curved stair tools Select Build> Stairs> Curve to Left or Curve to Right from the menu, then click once in a floor plan view to add curved stairs … Now that you have your measurements, it's time to begin assembling the stairs. Circular stairways have the advantage of requiring less floor and wall space than their more traditional counterparts. To allow for a 1-inch overlap, we will make the treads 13.5-inches deep (the horizontal measurement, front to back) at the outside end. Step 2 - Start with the Center Pole. We're going to build a wood spiral stair … Spiral staircases are attractive and functional, shrinking the staircase footprint to as little as 14 square feet. Spiral staircases efficiently tuck away in spaces too tight for a conventional staircase… A spiral staircase offers advantages to your home unparalleled by a conventional straight staircase. How to Design Circular Stairs. Since the riser has to run past the front stud at each stair … I am always careful to save my straightest material to make the tall studs toward the top of the stairs. One way is to place a spiral staircase from the Library Browser while other methods require the use of the Stair Tools.