While most residential spiral staircases are designed as secondary access stairs, this unique metal-wood hybrid staircase meets all the building code requirements of a primary access stair. Similar to larger curved staircases, this elegant spiral staircase has a wider diameter (88 "), shorter rise between steps and an inside handrail. Tile-inlaid pan treads, flat bar intermediate rails and a solid oak top railing make this spiral residential stairway as eye-catching as it is functional.