Guide to Standard Spiral Staircase Dimensions (with Drawings)

Spiral staircases are commonly seen in industrial settings, but they can also be used in residential properties as a style element or in an effort to save space and increase usable square footage in a room.

Spiral staircases are available in a variety of sizes to suit different needs, which we will address below.

Typically, spiral staircase sizes vary with the smallest standard spiral staircase having a diameter measurement of 3 feet 6 inches and a walking path width measurement of 17 inches to the largest standard spiral staircase with a diameter measurement of 6 feet and a walking path width measurement of 32 inches.

Check out the drawing below with great details.

Spiral Staircase Dimensions

What is a Spiral Staircase?

A spiral staircase is based around a central pole, with a simple design that makes installation quicker and easier than a regular staircase. It is this central pole that provides the structural integrity of the stairs, and therefore no other reinforcements or supports are needed.

It is this design that means a spiral staircase is great for saving space because it will go directly up to the next floor, rather than diagonally across a room like most staircases.

Because the pole is in the center of the staircase, there is only a handrail on the outside of the staircase, so it might not be the best type of staircase to use for anyone who is a little unsteady on their feet.

Added to this, spiral staircases tend to be steeper than regular staircases, which might be a safety concern for some people, such as those with children or elderly users.

Smallest Standard Spiral Staircase

The smallest size of spiral staircase available from most manufacturers will have a diameter measurement of 3 feet and 6 inches.

This is known as a space-saving staircase because it takes up very little square footage in a home, which can free up a large area of the room if you were to replace a standard staircase with this type. With this size of spiral staircase, you would obviously have a reduced stair width, which you would need to check is suitable for your family and the way the staircase will be used.

The walking path on a spiral staircase, which is 3 feet and 6 inches in diameter, will be 17 inches across, which is just under 1 and a half feet.

When you compare this to a standard staircase, which will usually have a minimum pathway size of 32 inches, you can see that this is a very slim staircase. You should consider how often the stairs are going to be used, and who will be using them, to see if this size will be suitable.

You should also think about whether you will need to carry items up and down the stairs and whether these items would comfortably fit through a 17-inch path.

Largest Standard Spiral Staircase

The largest standard spiral staircase you are likely to come across will have a diameter measurement of 6 feet. Spiral staircases can be made in bigger sizes than this, but they will ordinarily be custom-made to fit the space and the client’s requirements.

A 6-foot diameter spiral staircase will have a walking path width measurement of 32 inches, putting it on par with the standard minimum path size of a regular staircase.

If you find a regular staircase reasonable to use in terms of the path size, then you should get on fine with a 6-foot diameter spiral staircase.

Other Spiral Staircase Sizes

Spiral staircases typically come in diameter measurements of 6-inch increments starting at 3 feet and 6 inches, working up to 6 feet. Six inches is the equivalent to half of a foot. The next size up from 3 feet 6 inches will be a staircase with a diameter measurement of 4 feet.

This size of spiral staircase will have a path size of 20 inches. The next size up will be a spiral staircase with a diameter measurement of 4 feet and 6 inches, and this staircase will have a walkway size of 23 inches.

The next size up will be 5 feet in diameter, with a walkway path of 26 inches, and the following size will be 5 feet and 6 inches, with a path size of 29 inches. The final size is the largest standard size of 6 feet in diameter.

Walkway Path Size

Walkway Path Size

A good way to test whether the path size will be suitable for you is to use a sliding door. If you have a sliding door in your home, such as French patio doors or a sliding closet door, open it so that the width measurement is equal to the path size of the spiral staircase you are interested in, and then walk through it.

This will give you a good indication of whether you are happy with the path size. As spiral staircases are available in 6-inch increments, you can open the sliding door further to see how much difference it would make to the size of your walking path if you went for the next size up of the spiral staircase.

Floor Opening Sizes

Floor Opening Sizes

To install a spiral staircase in a home, you will need an opening on the upper floor where the top of the staircase will be fitted. The size of the opening will differ depending on which size of spiral staircase you choose.

If you are opting for a spiral staircase as a means of maximizing the square footage on the upper floor level, then knowing how big the opening will need to be could impact your decision. The minimum opening sizes for each common size of spiral staircase is listed below:

  • Spiral staircase diameter of 3 feet 6 inches will need a minimum floor opening of 44 inches by 44 inches.
  • Spiral staircase diameter of 4 feet will need a minimum floor opening of 50 inches by 50 inches.
  • Spiral staircase diameter of 4 feet 6 inches will need a minimum floor opening of 56 inches by 56 inches.
  • Spiral staircase diameter of 5 feet will need a minimum floor opening of 62 inches by 62 inches.
  • Spiral staircase diameter of 5 feet 6 inches will need a minimum floor opening of 68 inches by 68 inches.
  • Spiral staircase diameter of 6 feet will need a minimum floor opening of 72 inches by 72 inches.

Read also:

  • Stair Component Dimensions – All You Need to Know