# How to Take Measurements for Your Spiral Staircase

## Floor-to-Floor Height

Of the standard stair dimensions, the most important measurement when planning your spiral stair design is going to be your floor to floor height. To measure your floor to floor height, take a tape measure and start at the bottom floor and measure up to the floor where your stair is going. For example, if you are installing a stair on a deck, your floor to floor measurement would be the length between ground level and the finished deck flooring. Generally, our stairs are installed in two ways: coming off a deck, loft, building, etcetera or the stairs are installed through a hole in a floor. If you are installing a stair through a hole in the floor, you can simply measure from the bottom floor to the top of the opening. Be sure to account for any concrete, underlayment, subfloor, carpeting, or tile in your measurement.

Rotation

When you think of spiral stairs, you might imagine round stairs with a beautiful 360 degree spiral that has a whimsical winding shape. Each Salter Spiral Stair is unique all the way down to its rotation. As a custom shop, we can build your stair to your specification, so standard stair dimensions don’t have to be so standard. The specification that determines the rotation of your spiral stair is floor to floor height. Please refer to the table above for a reference on how to calculate the rotation of your staircase. Most, but not all of our stairs use 30 degree treads. In other words, each tread represents a 30 degree turn. Using the table above you will notice that 9 treads gets you 270 degrees of rotation (9 treads x 30 degrees = 270 degrees of rotation). A full 360 degree rotation means that you will exit the same at the same angle you entered onto the stair.

Well Opening
Stair Diameter Well Opening
3′-6″ 44″ x 44″
4′-0″ 50″ x 50″
4′-6″ 56″ x 56″
5′-0″ 62″ x 62″
5′-6″ 68″x 68″
6′-0″ 74″ x 74″

If your project includes a hole in the floor (likely a round hole for the round stairs) that calls for a spiral stair you will want to pay close attention to our well opening size dimensions. If you’re installing a stair through a hole in the floor, making sure you have the right size opening for your new spiral stair is key. We call this hole in the floor a ‘well opening’. Depending on where you’re putting the stair, your well opening size may be determined for you. If you want to utilize the space saving features of your spiral stair, and keep it in the corner of your room, walls may limit the size of your well opening. The smallest well opening that we can work with is 44” x 44”. This is because the smallest diameter we offer is 42″ x 42″ (3 foot 6 inches). A 44″ x 44″ well opening ensures that your fingers will not get pinched as you grab the handrail when you traverse up and down the stair.

Please note, that if you’re attaching your stair to the side of you loft or deck, you won’t need a well opening measurement, but you will need your diameter and footprint in the next section.

## Spiral Staircase Diameter

Spiral Staircase Diameter & Footprint
Stair Diameter Footprint
3′-6″ 42″ x 42″
4′-0″ 48″ x 48″
4′-6″ 54″ x 54
5′-0″ 60″ x 60″
5′-6″ 66″x 66″
6′-0″ 72″ x 72″

Because spiral stairs are often used for their space saving features, many people are concerned that the stair will be too narrow for regular use. We call the actual walkable room on your tread the clear walking path, which helps you meet stair tread code. This is a major measurement as you want to be comfortable walking up and down your stair. Some spaces call for a 3’-6” diameter stair. As this measurement only gives you a 17” clear walking path, they are normally used as a secondary means of access. While this is a perfectly safe diameter and walking space size, if you have more room you may want to look at larger diameters. You gain 3 inches of walking space for every 6 inches of diameter. Our 5’ diameter stair meets code and allows for 26” of clear walking space. This probably the closest that you will get to a traditional stair walking path.

## Platform Sizes

3′-6″ 20.5″ 9.5″ 11.5″ 13.5″ 7.31″
4′-0″ 23.5″ 9.5″ 13.25″ 15.25″ 7.31″
4′-6″ 26.5″ 9.75″ 15″ 17″ 7.31″
5′-0″ 29.5″ 9.75″ 16″ 18″ 7.31″
5′-6″ 32.5″ 9.88″ 17.5″ 19.5″ 7.31″
6′-0″ 35.5″ 10″ 19.5″ 21.5″ 7.31″

### Start Designing Your Spiral Staircase Today

Spiral stairs are a unique product that can be customized to meet all of your design specifications. If you have more questions about spiral staircase measurements and dimensions, give one of our consultative designers a call! They can answer any question you may have about your spiral stair design and help you find the best size for your space.

Take the first step in your spiral stair purchasing process with our quick How-to guide.

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