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From Start to Finish: Ensuring a Smooth Installation Experience

Installation Instructions

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Frequently Asked Questions

Finished Floor-to-Floor Height
The most important measurement that you’ll need to know for how to build a spiral staircase is your finished floor to finished floor height. Every stair is custom built to fit your space and an accurate floor to floor height is the first step to starting your project. Your finished floor-to-floor height will determine how many steps, or treads, are in your stair and the rotation of your spiral stair.

You can measure your floor to floor height by starting at the bottom floor where you will be installing the stair. From here, measure up to the finished floor and include any sub flooring or carpeting for the most accurate measurement.


While the floor to floor height of your spiral stair is the first measurement you need, knowing your preferred diameter can be useful as well. Diameter is just the width of the stair. Your diameter may be defined by the staircases’ surroundings. For example, if you want a loft stairs kit and you’re attaching your spiral in the corner of your home to gain access to a loft, think about how much space you have available for your staircase. If you’re unsure about the diameter, our consultative designers can help determine the right size stair for your project.

Diameter can be defined as a straight line going through the center of a circle connecting two points on the circumference. In other words, when we ask you what diameter you would like for your stair what we are really asking is, “How wide do you want your spiral stair to be?”

While going through a hole in the floor is a common application for spiral stairs, many of our customers install a loft stair kit at the face of a loft or deck. If that is the case you will want to think about two things: your desired clear walking space and whether or not you want to meet building code.

When we talk about “clear walking space,” we are focusing on the physical area you have to walk up and down the stairs. One of the major benefits of a spiral staircase is the large surface of each step in a small space. This amount of clear walking space is determined by your stair’s diameter.

Clear Walking Space Guide
Stair Diameter Clear Walk Space
5′ 0″ 26″
5′ 6″ 29″
6′ 0″ 32″


It can be hard to envision these measurements without physically seeing them. A quick trick to seeing your clear walking space is to use a sliding door in your home. Slide open your door to match the clear walking space for your diameter. For instance, if you choose a 5’0” diameter, open your door exactly 26”. This 26” represents the clear walking space you would get with our smallest 5’0″ stair. Use the chart above as a guide to determine what the most comfortable walking space is for you and your guests. This can help you narrow down your diameter measurements if you’re having difficulty. Generally speaking, a stair with a diameter of 5′ or larger is going to be very comfortable for your application.

Spiral stair building code requires your stair to have at least a 5’ diameter. Our 5’, 5’6” and 6’ code package stairs will meet code in many states across the nation. Now that you know a little more about spiral stair diameters, check out our building code page to learn more about code requirements of your spiral stair.

If you have any additional questions about your stair’s diameter or building code, call one of our consultative designers for instant answers!

One of the first questions that homeowners have when considering a spiral stair is, “How much space will I need to install a spiral stair. There is not set space requirement, it all depends on your unique space needs.

Your spiral stair’s footprint is another way of saying the amount of space the staircase will take up in your home. Because your stair’s diameter is the total width of your stair, it will also determine the footprint. The smallest spiral stair diameter that we offer is 5’0”, which translates to a 62” x 62” footprint. From here, the footprint will increase in 6” increments like the diameters.

Determining your spiral stair’s footprint can help you find the best size spiral staircase for your design. Often times, a customer wants to tuck their spiral stair into a corner against the wall and isn’t sure how much space they truly have for their stair.

If you think a 5’0” stair is the right fit for your space, mark a 62 inch by 62 inch space on the floor with tape. The area that you mark will essentially be the footprint of the stair and it will give you an accurate idea of how the stair will fit in your space.

For any additional questions, feel free to call one of our consultative designers. They can help you find the best stair for your space and help you through the entire design process.

When people think about spiral stairs, they picture a full spiral. However, not every spiral stair completes a full rotation! The rotation of your spiral staircase is dependent upon your finished floor-to-finished floor height. While every Trex spiral stair is custom made to fit your space and design dreams, this example will use a code compliant staircase.

Spiral stair building code calls for 30 degree treads. This means that each tread rotates 30 degrees around the center column. After you’ve found your floor to floor height, your consultative designers can help you find the right number of individual steps on your staircase. Take this number and multiply it by 30. For instance, if you have 12 steps, or treads, you will have a full 360 degree rotation.


Rotation Reference
Number of Treads Rotation
9 treads 270°
10 treads 300°
11 treads 330°
12 treads 360°
13 treads 390°

Once you’ve measured your floor to floor height, call one of our consultative designers find the number of steps that will work in your space. All you need is one measurement to start your project! If you have your measurement but no time for a call, fill out our quick form for one of our designers to call back later. You can give us your measurements and some basic facts about your project. Our consultative designers will call you at a time that’s convenient for you.

Installing your own spiral stair may seem like an intimidating task, but our DIY spiral staircase lines make it an easy weekend project. Once your spiral stair is ready to be shipped to your location, our shipping company will call to schedule the best time for you. We ship our stairs in kit form meaning all of the individual parts of your stair are broken down and wrapped to make shipping and handling easier. Once you have all of the parts laid out for installation you are ready to begin the process. Your spiral stair goes together like a large erector set with the help of a spouse, friend, or neighbor.

Our customers range from experienced contractors to do it yourself homeowners, but they all can install their spiral stair themselves.

When you’re buying something as big as a staircase, you may be nervous about our designers never seeing the physical space. Our stair experts are dedicated to making sure your dream spiral staircase will fit your space perfectly. One way we ensure the right fit for your space is using AutoCAD as a part of our design process.

AutoCAD is a computer program that allows our designs to produce a digital rendering of your spiral stair in your space. We work off of your pictures, measurements, and anything else you can give us.

Once we have a picture of your space we will do an online design meeting with you and show you how your stair will be custom built for your space. We do not give you a generic stair that may or may not fit your space – we build your stair your way and let you pick all of the options.

You can watch our designers draw your stair live from home right on your computer screen. Once we are both satisfied that the design meets your needs, we will send the design to the shop where everything is cut and fabricated to your exact specifications.

Our unique consultative design process gives our customers a one of a kind customer experience.

Depending upon your space and project, your spiral stair may not have to meet building code. Our stairs’ safety is never in question, whether you choose to meet building code or not. In other words, the structural integrity of your stair remains the same regardless of whether you choose a code stair or non-code compliant spiral staircase.

There are some instances in which you will have to install a code compliant stair. You will want to meet building code if you plan on pulling permits for a project. If you’re going to have an inspector come out to look at your home and spiral stair, you will need to meet building code to pass the inspection. Here are a few scenarios in which you will want to purchase a building code compliant spiral stair:

If your spiral staircase is the only means of access to an area of your home, you will need to meet building code. One example of this would be if you decided to replace old basement stairs with a newer and more stable spiral staircase. Because it will be the only way to access your basement, it will need to meet building code.

Many of our customers install a spiral staircase in a home that they are preparing to sell. For example, if you are installing a spiral stair on a deck in your backyard and you plan on selling to home soon then you can expect an inspector to come out and look at your stair. In this case, you will want a code compliant stair.

There are some cases that you may not need to meet building code.

Here are some examples:

  • If your spiral stair is a second means of access, you may not need to meet building code. For example, if you already have a code compliant stair leading up to the second floor of your house, but would like a smaller secondary means of access in a corner, your spiral stair will not have to meet building code.
  • You will not need to meet building code is you are providing a safer and better means of egress to a floor. For example, let’s say you want to replace your attic stairs and a spiral staircase. For the purposes of this project you may not need to meet building code because you are providing a better and safer means of egress to that attic. While this is a case in which you wouldn’t need to meet building code, every municipality has different requirements. Check with your local code officials to be sure that this is the case.
  • If you don’t plan to sell your home or you plan to pass it down through the family, you may decide not to have an inspector come out to the house. In this case, you won’t need to meet building code. The home won’t go through a formal inspection.

You might also choose a non-code compliant staircase if you simply do not have enough space for a code stair. Remember, building code requires a 5 foot diameter stair. A 5 foot diameter stair has a 60 inch x 60 inch footprint and some customers do not have enough space to accommodate a 5 foot diameter stair. As we mentioned before, code and non-code stair do not differ in their structural integrity.

These are just a few example scenarios of when you might choose to meet building code or choose a non-code compliant stair. Many homeowners are unsure of building code requirements and whether a code compliant stair is needed for their project. If you have any questions about spiral stair building code and how it relates to your design, call one of our consultative designers! They can answer all of your questions within minutes.

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Reach out to our experienced team for quick help and personalized solutions. Here’s what you’ll get:

  • Quick and accurate pricing
  • 3D Model of your staircase in your space
  • Design options that perfectly fit your budget
  • Estimated product lead times

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