How to Build a Spiral Staircase

spiral staircase in the home

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A spiral staircase offers advantages to your home unparalleled by a conventional straight staircase. 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: kitchens, halls, and foyers.

Building your own spiral staircase is an advanced home improvement project for do-it-yourselfers, especially if you need to create a staircase well in the upper floor. Assistance from a partner is required. The results are rewarding, and your home will benefit from this high-value project.

Should You Use a Spiral Staircase Kit?

Spiral staircase kits include carefully machined steel parts that fit perfectly together with little tolerance for error. Metal treads nest on top of each other, around a strong metal pole that provides most of the support. Treads, pole, spindles, handrail, balusters: all are specialized parts unavailable piecemeal at most home centers. To produce these parts from scratch, you would need machining tools, welding equipment, and the skills that go along with each. Most do-it-yourselfers find it safer and more efficient to construct their spiral staircases from kits.

Safety Considerations

Staircases, especially spiral staircases, can be dangerous if not constructed and used properly. Begin with a spiral staircase kit from a reputable manufacturer. While instructions in this guide illustrate features shared by most spiral staircase assemblies, instructions included with your kit should take precedence over instructions in this guide. Be especially careful of the open well area on the upper floor.

Codes and Permitting

Call your local permitting office for information about spiral staircase codes and building permits. Due to spiral staircases' unique sizing, local code for spiral staircases usually will differ from that of straight staircases. For example, your local code may permit risers up to 9 1/2 inches. Code for straight staircases often specifies riser heights of no more than 7 3/4 inches.

Spiral Staircase: Well and Center Pole Calculation Chart
Stair Size Well Size (Squared) Pole Position
3 feet, 6 inches 3 feet, 8 inches 22 inches
4 feet 4 feet, 2 inches 25 inches
4 feet, 6 inches 4 feet, 8 inches 28 inches
5 feet 5 feet, 2 inches 31 inches
5 feet, 6 inches 5 feet, 8 inches 34 inches
6 feet 6 feet, 2 inches 37 inches

Project Metrics

  • Working Time: 2 days
  • Total Time: 3 days
  • Skill Level: Expert
  • Materials Cost: $1,000 to $2,500

What You'll Need

Equipment/Tools

  • Drill
  • Tape measure
  • Set of manual screwdrivers
  • Laser level with plumb or a string plumb bob
  • Hammer
  • Hacksaw
  • Set of wrenches or socket wrenches
  • Adjustable wrench
  • Safety glasses
  • Ladder

Materials

  • Set of drill bits
  • Set of masonry drill bits (optional)
  • Lag bolts
  • Concrete anchors (optional)

Instructions

  1. Measure Height and Well Requirements

    With the tape measure, measure the distance from the lower floor to the walking surface of the upper floor (not the ceiling of the lower floor). Use this height when ordering the spiral staircase kit since you will be required to specify the number of stair treads needed. Calculate the area of the staircase well by measuring length by width.

    Tip

    Be precise about measuring height. The treads must stack up to just the right height so that the top landing exactly meets the upper floor.

  2. Locate the Center Pole

    On the ladder, measure halfway out on two sides of the staircase well. For example, if the well is 3 feet, 8 inches in square, half of this is 22 inches. You would measure out 22 inches on two adjoining sides. Plumb down to the floor with the laser level or the plumb bob to locate the attachment point for the center pole on the lower floor.

  3. Attach the Base Flange

    Place the center pole's base flange on the center point marked in the previous step. Attach the flange to the floor with lag bolts. Use concrete anchors if the floor is concrete. Use the wrench set or socket wrenches to drive the lag bolts firmly into the concrete or wood floor.

  4. Attach the Center Pole

    Slide the center pole into the base flange. Have the partner hold the pole firmly and as close to plumb as possible.

  5. Attach the Treads

    Move all of the treads to the upper level. Carefully slide the treads down the pole; do not let them fall. The partner on the lower level, standing on a ladder, will control the descent of the treads and let them gradually stack up. Some spiral staircase systems require spacers between treads. If so, be sure to have the spacers on the upper level and add them accordingly.

    Tip

    Metal treads are heavy. If all are stacked in one direction, they can tip the pole. Stack the treads alternating left and right to maintain the pole's vertical plumb.

  6. Secure the Landing

    Once all treads are in place, slide the top landing over the pole. Attach the landing to the upper level using the method prescribed by the staircase manufacturer. Typically, lag bolts attach the landing to the sides of the floor joists.

  7. Rotate the Treads Into Position

    Rotate the treads sequentially so that they form an upward corkscrew or helix shape.

  8. Attach the Spindles

    Spiral staircase kits always have a system that both aligns the treads and provides balusters for the handrail. Many kits use separate spindles that attach from one tread to its upper neighbor. Attach these spindles as recommended by the manufacturer.

  9. Attach the Railing

Many spiral staircase kits have a railing that is delivered in the form of a tight coil. With your partner, widen the coil until it is the diameter of your spiral staircase. Then, slowly walk away from each other to draw out the railing so that it forms a corkscrew. Attach the railing to the spiral staircase's balusters using the included hardware.