The standard stair width varies depending on your region and the type of building you are referring to. Residential homes have narrower staircases than public spaces which need quite a bit more room.
While the numbers are different, it can be easy to find out what size of stairs you need. First off, you find the common width and follow any codes in your area. From there, you can create the perfect staircase for your home.
Note: this is the average stair width in America, though it is common in other countries too. That said, some countries follow different guidelines and thus have narrower or wider stairs in their homes.
What Is The Standard Stair Width?
The average stair width is about 36″ wide which is actually the minimum according to most building codes. Though the entire 36″ isn’t used, it is enough to account for handrails which can take up a few inches.
A railing can take up anywhere from 2-5inches each. If you have a railing on both sides, that’s up to 10-inches. This makes the space used for the step 26-inches minimum. So you can see why there is a 3-feet minimum to start with.
This minimum isn’t always enforced but even if it is not, it is highly recommended. You’ll be surprised to see how narrow a staircase with 10-inches taken from it is so prepare for this difference ahead of time.
Average Stair Height
We’ve gone over the average stair height before. The appropriate step height for your home does depend on your family and your common guests. But a good standard step height is 7.5 inches with a depth of 9 inches.
This is a good height for most individuals. Much taller and shorter people will struggle and any shorter and you’re just wasting space and materials. So in general, this is a good dimension for stair height.
As for the entire stair height, this depends solely on the floor or ceiling height. Most floors are about 8-feet tall so this is how tall most stairs are in residential homes. Though they will always match the first floor’s height.
This is a bit tricky. A spiral staircase should have steps that are at least 36-inches wide just like any other staircase. But it’s the diameter of the staircase that will determine how big the steps end up being.
Spiral staircases need to be at least 5-feet in diameter though 6-feet is recommended. This gives the steps each 36-inches with the center support and the outer handrail. This is the standard, safe size.
Most spiral staircases won’t be wider than 6-feet. Though there are occasions where they are narrower than 5-feet, in studio apartments for example. However, this is not recommended, as 5-feet is already quite narrow.
When it comes to staircases, no matter the shape, the width must be at least 36-inches for each step. The same type of rule can be applied to the railing. For safety reasons, primarily with children, the railing has a code.
Each spindle must be no more than 4-inches from the next one. The space between each must be no more than 4-inches so that tiny arms and legs cannot pass through them easily and lead to accidents.
As for the bottom of the steps, you need to have no more than 6-inches between the bottom of the railing and the floor or step. This is in place for the same reason, though again, 4-inches is recommended.
The average railing height is 36 inches. The range can be anywhere from 34 inches to 38 inches, though this is up to your preference. It’s important that it is low enough that you can hold onto it when going down the stairs.
But it is even more important that you won’t fall over it. Especially children who tend to push the limits. So ensure that you follow these guidelines as closely as possible for the safest staircase that you can build.
Parts Of A Staircase
Learning the parts of a staircase can help you design your own and make sure that it is structurally sound. Though you don’t need to remember the names, remembering what each part does is important.
There won’t be a quiz afterward, so don’t worry, you can’t fail. It’s all for personal educational purposes. Now, here are the parts of a staircase that are important to learn if you are building your own house.
There are two different “runs” in stairways. The first run is the run of the step which is the width of the step itself. Not the length, but what we would normally consider the depth. Where your foot will land.
The other type of run is what makes up the entire staircase. This is how long the entire staircase is and is the bottom number you will use to figure up how much space your staircase will take up when you’re finished.
The rise is the opposite of the run in terms of measuring. It is the vertical space rather than the horizontal space like the run. The rise is how tall each step is as well as how tall the entire staircase will be when finished.
The total rise will be the second number you will use to find out how much space the staircase will take up. You take the total run number and multiply it by the total rise number to figure up the area the staircase will take up.
The stringer is another term similar to height. Stringer refers to the diagonal length of the stairs. You can easily measure this by starting at the floor and holding the measuring tape straight to the opening above.
Just makes sure you measure the bottom of the stairs instead of the top. Imagine a beam that the stairs will sit on and this is the stringer length. This is an important measurement for finding the right board length.
Nosing is an overhang that is above each step. Not all steps have a nosing but many do for aesthetics. It also makes it easier to see the next step, which is safer, especially if the nosing is a different color than the step.
To create a nosing, simply make sure that the board used for the tread (more on that later) is a centimeter to an inch deeper than the run of the step. This will give a natural overhang without any extra effort.
The angle is fairly self-explanatory. It is the angle of the stairs. This is relative to the floor from the bottom of the stairs. you can use a square or another similar tool to find the angle of the staircase.
You don’t need to find the top angle, just the bottom angle. So after you measure the stringer, find the angle by measuring the angle of the stringer as it is relative to the floor on the bottom, not the top of the steps.
The tread isn’t something you need to know before constructing the steps. It is simply the material used to cover the steps. This can be boards, carpet, or something else. But you do need a solid tread before covering it.
Most treads are made with 2x8s but they can be made with 2×6 or 2x10s. This is the base for the tread that can then be covered. Using one-inch boards doesn’t usually work as well as two-inch boards.
Headroom is a term used to describe the shortest distance from the steps to the ceiling. This is very important because headroom should be at least 80-inches to accommodate anyone who might visit you.
In public spaces, this amount of space is even greater, just like the stair width is even greater. But you can get by with 80-inches. Less if your family is shorter than average, though this is a good height anyway.
The mount is where the stairwell ends. The mount can either end just below the ceiling, be flush with the ceiling, or step up a little to create a platform above. This is all up to you and how things work out.
The type of mount you use doesn’t matter though a flush mount is the easiest to use and the least likely to trip someone. So for safety reasons, it is the most common type of mount used on residential stairs.
Can I Use A Narrow Step?
This all depends on the codes in your area. In most cases, you can build whatever type of staircase you want in your home. But there are exceptions. For example, if you live in a condo you’ll have to talk to HOA.
If you live in a duplex, you’ll have to talk to the landlord or the other family living there. Because in most cities and counties in the United States, appropriate stair width is recommended but not enforced.
To find out more, call your local building code department to find out. You may have to get a permit to build anyway, so it’s a good idea to check with them before you start building anything, even your own home.