“Stair angle”–or the angle at which your stairs descend–plays a crucial factor in deciding how to build handrails for your stairs. This short article will show you two extremely easy tips for calculating the angle–or “pitch”–of your stairs!
I’ve included a short video with this article for the sake of convenience, and so you can see the process carried out in real time.
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An ANGLE FINDER is the quickest way to find stair angles!
A SPEED SQUARE can also play a crucial part…
When paired with a 2′ LEVEL!
1. Understanding Stair Angle And Handrails
I don’t think anybody needs a real explanation of what stairs and handrails are for. But, it’s important to have a little insight into how stairs and handrails interact with each other.
By code, the tops of handrails are typically supposed to sit 34″-38″ above the nose of any given stair. For this reason, it’s absolutely necessary that your handrail follows the exact same pitch as your stairs.
If the handrail is set at a steeper pitch than your stair angle, it will nosedive towards your stairs at the bottom. If it’s set at a shallower angle, it will wander upwards, getting increasingly closer to your head as you descend.
Either way, it’s going to wind up looking dumb. And, it’ll be laughably out of code compliance.
So, in order to determine your handrail height, we first have to determine your stair pitch. The next steps will show you how to do just that.
2. Establishing Your “Stair Line” Angle
Stairs are made up of a series of “rises” and “runs” that break up the vertical distance between a low point and high point. The ledges created by these rises and runs act as comfortable places for our feet to land on as we ascend the stairs–but, they create a visual sawtooth that is hard to read as a simple angle.
For this reason, it’s necessary to use a tool that helps us visually convert the ledges back into a true slope.
Really, any reasonably long and straight object will work in this application. I like to use a 2×4 as a “straight edge.” But, I first make sure it’s not bowed by sighting down the length the material from one end to the other, examining all the faces.
Confident that the 2×4 is straight, I lay it down along the noses of all stairs, letting it butt into the ground down at the bottom.
I typically see little variations here and there, places where the straight edge touches some stairs but not some of the others. That’s okay–we’re really looking for the average angle of the staircase, which the 2×4 has revealed.
Having established this visual line, I can use a few other tools to easily calculate the pitch.
3. Using An Angle Finder To Determine Stair Angle
An “angle finder” is a tool that simply indicates the pitch of anything it is resting on. A needle arm swings across a dial face behind a window on the tool. This needle always wants to point directly upward, perpendicular to the horizon.
When you set the flat bottom of the angle finder on a flat surface, the needle will point to a degree mark on the face. That number (or tick line between printed numbers) is your given angle.
That’s it! The angle finder does all the hard work for you. It just needs a flat place to sit, and a moment for the needle to come to rest.
Stairs aren’t the only application where the angle finder comes in handy. It can read the pitch of a roof, a driveway, or angled trim anywhere in your home. Because it’s so universally useful and cheap, I really advise getting one!
If you don’t have an angle finder, or you just want to corroborate your findings, the next tip will show you how to do the same thing with two more common tools.
4. Using A Level And Speed Square To Find Stair Angle
A “speed square” is a triangular tool that has about a million uses in carpentry. We’re going to use it in conjunction with a 24″ level to calculate our stair angle.
The first thing you want to do it set one end of your level down on your straight edge. Holding the free end of the level in your hand, tilt it upward or downward until the spirit bubble is exactly between the two marked lines in the window.
Now, take your speed square and hook the little rail on one of the shorter legs onto your straight edge, also butting it up to the underside of your spirit level. Rotate the speed square upward until the entire rail is resting against the underside level. (This is probably easier with two people.)
Look closely at your speed square. Printed or engraved marks on the long leg indicate every degree in a 90-degree arc. Whatever mark the top edge of your straight edge is passing through is your pitch.
This number should be the same–down to about a single degree–as your angle finder reading.
You now know the exact angle at which to set your handrail so that it matches the descent of your stairs. Use this stair angle number for the miter cuts on the ends of your rails and balusters (if you’re incorporating any), and you’ll have a railing system that looks even and plumb.
(If you have any questions about anything I’ve discussed here, feel free to send them to me through the Contact page.)