Stair riser height & construction questions & answers:

Frequently-asked questions about proper height for stair risers or step heights when building or repairing stairs.

This article series provides building code specifications, sketches, photographs, and examples of the proper stair step height or stair riser dimensions and other stair riser requirements for indoor or outdoor stairways.

Sketch at page top courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

Stair Riser Height & Code FAQs

These questions & answers about stair riser heights and stair design were posted originally at STAIR RISER SPECIFICATIONS - be sure to read the stair design details given there.

On 2018-08-01 John R) - Can the top tread of a stair stringer be the same elevation as the finish floor ?

Can the top tread of a stair stringer be the same elevation as the finish floor ?

John F

On 2018-08-01 by (mod

That's an interesting question; you're basically extending the floor area by the width of a stair tread, right?

Why would you do that? It pushes the whole stairway out by the depth of the stair tread in move that would be unnecessary - but then I can't see your situation, perhaps I'm missing something.

I don't think we'll find an explicit prohibition in the stair codes, since the code writers can't and don't try to anticipate every possible variation on what people may invent.

But a local building code inspector MIGHT interpret that top tread as a stair top platform.

If she does, then the stairs would be improper as the platform would be very much too short.

A platform needs to run no less than 3 ft. in the direction of travel up and down the stairs, and yours would run what, maybe 11" - or whatever is your tread depth.

On 2018-06-30 by paula martin - report of a fall at 3-step stair in library

I lost my balance on the bottom step of 3 steps at a local library.

The claims examiner as an employee of Carl Warren & Co. which handles claims for the city insists that the steps are safe as well as the city administrator although they haven't to date agreed to discuss with me what makes the steps unsafe other than to say that nobody has filed a claim because of a fall from the steps.

The carpet is at least 20 years old and appears to have some slippage, even though slight. The strips along the edge of the treads are worn due to heavy traffic and one strip is missing.

The carpet used for the steps is the same carpet used for the floor which indicates that in all likely hood carpet made specifically for steps has not been installed. The carpet for the steps and floor have a light blue pattern which gives the effect of the floor and steps as one.

I am concerned . It appears for a certainty that nothing will be done about making the steps safe.

On 2017-12-20 1 by (mod) -

Yes
20" as a single step up is too-high a rise and would be a trip hazard. Typically step rise should be around 7"

On 2017-12-19 by Jamrs - help me design a step between two deck surfaces 20" apart

I have two decks at different heights by 20 inches is a step required. ..jd

On 2017-11-25 by (mod) - fine tuning step riser height

What's the total adjustment in a 15 step stairway if the total rise really is 104.75" and instead of building steps that each rises 6.98" we instead make each rise 7" and how do we make that adjustment in individual stair riser heights?

The total error when we get to the top step is 15 steps x (7" - 6.98") or 15 x 0.02 = 0.3" or 3 / 10 of an inch.

The builder could divide the corrective adjustment total rise over three individual stair risers, by making each of the first OR last 3 risers 1/10" shorter than the 7" standard: that is, building the 3 risers at 6.9" and the rest at 7".

Having a stair riser that is 1/10" shorter than others in the stairway is a correction of 0.10" per step rise and is thus well below the 0.375" maximum variation allowed in a single step riser. It also makes the math easy for your builder.

On 2017-11-25 by Grant - the last and highest step (the porch/landing) 8.75 inches high - OK?

I am in the process of having an external masonry staircase and porch landing demolished and rebuilt from scratch. At the bottom of this staircase is the sidewalk, and at the top, is the porch that leads directly to my front door.

This is a single-family house in NYC. I hired a contractor, who has demolished everything and is currently in the process of building it back. He started from the ground up and made it all the way up to the last step (there were about 13 to begin with, including the porch/landing).

Today, he was pouring the concrete for the porch/landing and it was about 85% poured, when he called me over to show me something. He told me that every step was exactly 8 inches high, except that the last and highest step (the porch/landing) would be 8.75 inches high.

He asked me if this was ok. I told him, I wasn't a lawyer and didn't know if it was ok. He said "It's ok, it's ok" and he finished pouring the concrete and smoothed it out nicely and left without telling me he was leaving for the day.

I am concerned that this will be a trip hazard. .75 inches of a discrepancy in riser height seems a lot to me, and it is certainly more than the .375 I have read here is the maximum allowed or recommended.

This contractor built this staircase from scratch, so it seems to me that had he done his calculations correctly, and been paying attention, he could have avoided this problem. Is there anything that can be done at this point to remedy this?

Does he have to demolish what he's done and redo it?

Or is the riser height discrepancy not that big of a deal? The steps are poured concrete over a deck sheet, supported by 4 metal beams, supported by side walls. Underneath the staircase is hollow. The risers and treads are limestone. Thank you very much for your help.

On 2017-11-25 by (mod) - the last and highest step (the porch/landing) 8.75 inches high - unsafe irregular step riser heights

What you describe is not a safe nor acceptable nor Code Compliance stairway. Not only are your risers a bit high but you would have too much variation of the last step.

It's more than an issue of Code Compliance and passing a final inspection that's also an issue of people falling and being injured.

On 2017-11-25 by Grant - how do I fix this?

Thank you What can be done from here? Does he have to demolish the staircase and do it again? Is there any other way of correcting it? Demolishing it all and beginning again would be a big job, but I will instruct him to do it if necessary.

On 2017-11-25 by (mod) - how to fix a too-high final step rise

Grant

I can't make a reliable prescription for a site I know nothing about. But sometimes it's possible to correct an improperly built concrete stairway by increasing the length of the run and then pouring or building new stairs atop what was already there.

If you had 13 risers (at 8") and if I GUESS that you had a stair tread depth of 10" and if the stair builder had any sense and made all the steps or treads the same dimensions, then your stair run would be 13 x 10 = 130" or 10.8 feet in the horizontal direction.

The ACTUAL stairway, AS BUILT, had a total rise of 12 x 8" + 8.75" (for that "last step) or a total of 104.75" (or I might be missing something as I don't really know your site)

Let's GUESS from the above that the total rise of the stairway was that amount: 104.75" over those thirteen unfortunate steps.

If you drop the individual step rise to 7" 104.75 / 7 = 14.96 steps to climb that height 7 inches at a time (per step)

So we can build a stair with 15 steps. The exact step rise would be 6.98" - so the builder can certainly make that 7" with almost zero adjustment to the individual tread rises and he can certainly keep the step rise uniformity well within spec.

Now if we have 15 steps with treads that are 10" deep then our new stair run (horizontal distance) is 15 x 10 = 150" or 12 1/2 feet.

If you have room to extend the stair run to 12 1/2 feet you're in good shape.

On 2017-10-09 by Freddy - how do I calculate the number of steps I need to ascend 94 inches

how many stairs do i need in 94" high finish floor?

On 2017-10-10 by (mod) - how many stairs do i need in 94" high finish floor?

Freddy

Let's do a back-of-the-envelope calculation. Assume a 7" riser height. 94/7 = 13.4 risers but since we can't have a fraction of a step, we either increase to 14 risers (giving a step height under 7") or 13 risers (giving a step height just over 7". Let's use 13.

94" total rise / 13 risers = 7.23" individual riser height.

In the real world I'd build my steps as 7 1/4" riser height - which would make the entire set of over its 94" rise stairs just 0.26" too tall overall - knowing that I would "lose" 1/8" or less over each of 3 risers or more - within acceptable riser height variation - in order to make the final stairway fit exactly the 94" total rise.

Typical codes allow up to 3/8" rise variation among steps. Do not make so much adjustment in a single step riser that you violate code or create a tripping hazard.

OR if your local codes prohibit step rises over 7" then go with 14 risers instead of 13. In that case

94" total rise / 14 risers = 6.71" individual riser height for each of 14 risers or steps "up".

On 2017-04-22 by Anonymous - What's the rule say about the height of the landing above the grade?

Here's a quiz question / conundrum

There's a typical exterior run of stairs in a house built in 2009. Made to code, it has a landing at the bottom like it should. But the landing is above grade by 10 or 11 inches. What's the rule say about the height of the landing above the grade?

On 2017-04-22 by (mod) - rule for height of landing above grade

If I were your building inspector (which I am not) I would point out that a "landing" that is above grade at its outer end in the direction of travel is in effect a step.

Since your step at that point has a 10-inch rise it's too tall. Properly the grade can be brought up to the landing's outer end OR you can build a 5 or 5.5" rise step of appropriate depth (since it's a low rise) down to grade.

Put another way, suppose you had to build a "stair" up from grade into your building entry and the total rise were 11" - you would not get away with a single 11" "step" now would you.

On 2017-02-05 by Jane - the steps may be upside down?

I have 3 steps and then my deck, I'm thinking that the steps may be upside down?

On 2017-04-18 by (mod) - ok to make steps of different heights? NO.

Jane:

What would be upside down? The tread surfaces? You're welcome to use the page top or bottom CONTACT link to send us photos for comment.

But NO, do not make steps with such uneven riser height. Even if you become used to the stairs, other people are very likely to trip and fall.

Here's an example code citation for stair step height or rise:

2008 NYS Stair Code: R311.5.3.1 - Stair Riser height Requirements. The maximum riser height shall be 8 1/4 inches (209 mm). The riser shall be measured vertically between leading edges of the adjacent treads. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm.) (Courtesy Arlene Puentes).

Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum.

Stair tread depths shall be 11 inches (279 mm) minimum. The riser height shall be measured vertically between the leading edges of adjacent treads.

For a 17.5" total rise height, I would figure the number of steps and riser height by finding a number close to 7" that will divide into 17.5" 3 times - thats because if I divided the height evenly in half your two steps would be 8 1/4" which is a bit tall (though your building inspector might accept those)

So let's divide 17.5 / 3 step risers = 5.8" rise height.

So your choices are 3 steps 5.8" high (those will want a deeper tread, say 13-14") or 2 steps that are a bit tall at 8.5" = subject to building department approval.

At https://inspectapedia.com/Stairs/Stair_Calculations.php you will find this subtopic CALCULATE STEP TREAD DEPTH https://inspectapedia.com/Stairs/Stair_Calculations.php#CalcTreads that talks about that dimension.

Generally when we shorten the rise height below about 6" we need to make the tread depth greater to avoid a trip hazard.

More details about stair tread dimensions including a discussion of tread depth is at https://inspectapedia.com/Stairs/Stair_Tread_Dimensions.php - STAIR TREAD DIMENSIONS where we discuss the requirements for uniformity in stair height and depth and slope

 

On 2017-01-11 by Anonymous - what's the right height for the last step down to the lower floor?

How high should the last step be to the bootem floor?

On 2017-01-11 by (mod) - ALL of the steps in a flight of stairs should be the same height

Anon

ALL of the steps in a flight of stairs should be the same height. Otherwise the steps are a trip-fall hazard. Don't make your last, or first nor any other steps vary .

- no step riser height variation from one step to another that is greater than 0.375 inches is acceptable

On 2016-06-15 by Mr T - There is no variances allowed for open risers.

There is no variances allowed for open risers. Think about going DOWN the steps and where your toes are now

The stair stringers in the photo are were installed upside down and the notches are cut at an acceptable depth.

On 2016-06-15 by (mod) - variances allowed for open risers

Mr. T thanks for the comments but we're stumped - don't know what photo you refer to. If you mean the photo of the tall rise steps to a deck with client showing the rise with a tape, "upside down" or not won't change the too-deep notch cuts that give almost no stringer strength - less than a 2x4 - nor the too-tall rise for this stair access from ground to deck.

 

On 2015-11-19 by Tom - In NY state what is the concrete riser height code for new walkways

In NY state what is the concrete riser height code when building new concrete walkways. Thanks. Tom.

On 2015-11-19 by (mod) - Walkways, i.e. sidewalks, are not stairs.

Sorry I don't quite understand the question. Walkways, i.e. sidewalks, are not stairs.

I would agree with the OPINION that if the edge of a walkway also functions as a step up from a lower level, at that point you'd want to respect the maximum stair riser heights discussed in the article above.

 

On 2015-11-12 by Anita Chapman - one step is 7" and the other 10"

The entrance to my kitchen is 17 inches above my garage floor. The current step is 7 inches in height, which leaves 10 inches to span to the kitchen. The first step seems low to me. Wouldn't it be better to have an 8 inch step, or even 8.5, in order to make them even?

On 2015-11-12 by (mod) - uneven steps are a trip hazard

Anita

I agree that uneven steps are a trip hazard;

The best solution builds steps that are not too tall (10" is too tall) but the problem we're going to encounter - maybe - is how much horizontal space you have in the direction of travel.

Let's design a stair for the total rise you cite:

Divide the total rise by 2 and your steps are over 8" and too tall.
so
Divide by 3: 17/3 = 5.6" - that's the rise you need to build, using 3 steps.

Now because that's a rather low step, you'll want to increase the tread depth - the distance from the step nose to the face of the vertical riser board.

I'd want my steps to be at lesat 12" deep - so we need 36" or more in the direction of travel.

If you can fit that you're in good shape.

Question: Using pre-fab stairs - Is there an exception to the riser height variation for the very first step of the staircase?

Is there an exception to the riser height variation for the very first step of the staircase? Let me attempt to clarify the question. I have a deck (exterior porch) for which the distance from the top of the deck to the slab which forms the footing for the set of stairs is just shy of the 5 steps within a pre-fabricated 5 step stair stringer which can be purchased at a Home Depot or Lowes, for example.

If I attach the pre-made stringer from the deck to the slab, ensuring that the top of the deck to the next stair down is the same height as the rest, then the riser height from the slab to the first stair is greater than a 3/8' variation from the rest of the riser heights by 1/8th of an inch (ie. it's 1/2 inch shorter than the rest of the stairs -

I actually need to remove a half inch from the bottom most stair of the stringer to fit). If this is a violation of code, than it means I need to cut my own customer stringer. Just verifying. Any feedback is appreciated. - Dan

Reply: no stair step riser height variation greater than 0.375 inches is allowed

Dan,

There is no exception for individual stair steps, first, bottom, top, or other. A difference in riser height can be a serious trip hazard at any location on a stairway.

Quoting from the article text above on stair and step height regularity and the amount of variation in stair step riser height that is allowed (presumably to avoid a trip hazard)

"Stair risers of uneven height - no variation greater than 0.375 inches is allowed"

Minor Adjustments can fit a factory-built stair to the specific overall stair rise

As I read your note, you have just a 1/2" error to make up between the total elevation difference between the deck surface and the ground surface if you use a pre-fabricated stair way.

If you can split the adjustment between the top and bottom stair risers by trimming the stringer top and bottom, you'll have just 1/4" or 0.25" of riser height variation (one at stair top and one at stair bottom) - thus minimizing the trip hazard risk of the uneven risers and the variation will be within standards.

Watch out: be sure to measure the height difference (deck surface to ground surface) at a projected point along a horizontal line from the edge of the deck out to the location, in horizontal distance, of the front edge of the nose of the very first or lowest step of the stairway. That will avoid any error in calculating total stairway height due to any slope in the actual ground surface.

If you need a greater adjustment in the stair height between the ground surface and the deck surface in order to avoid having to re-cut a whole new pair of stair stringers, sometimes that can be accommodated by changing the height of the surface of the concrete or other masonry platform that many building departments and local codes require be placed as a landing at the bottom of the stairs.

Question: how do we set the step riser height for a very low angle staircase?

Perhaps one of the experts here could give advise on this. What are the rules for a low angle staircase? I am planning an exterior (built on grade) staircase on a slope too steep for a ramp.

My rise is 78 in. over 28 ft. and there is additional room for a landing at top and bottom. I am considering 3 ½” risers and 16” treads (using commonly available cement block). What rules-of-thumb should I follow to build a comfortable walk-able low angle staircase?

If there is some formula to the ideal cadence; I would form this in concrete in order to achieve it. I do not want to feel like I am taking “baby steps” or alternately taking a “step-and-a-half” all the way up and down. - Tom 6/23/12

Reply: Here is a simple approach to calculating the stair rise & run for a low slope stairway

Great question. Bernie Campbalik who taught us carpentry, including stair building, used a rule of thumb that basically makes the run longer when the rise is shorter. I've seen several rules such as the sum of one tread and one riser should always be equal or greater than 17;

I think we need to dig out some texts on stair design such as those in the references. The concept is that a low rise stair usually has, just as you suggest, a tread that provides a "longer" walking surface. Up to a point. If we make the rise too short, say an inch, it's not a step at all, it's a trip hazard.

See details at STAIR BUILDING RULES of THUMB

Reader Follow-Up:

Dan, Thanks for your response. I now think any rule can at best only make general recommendations for all the low-slope possibilities.
I figured that if I could determine the optimum number of steps to comfortably traverse the distance of the slope of my proposed staircase I would then know the correct number of treads.

So I marked off the landing locations and simply walked up and down the slope while counting the number of steps I took as I did so. I repeated this a few times adjusting my gait somewhat and arrived at an average number.

In this case I took 14 steps to travel the slope which equates to 14 treads - 24” long. Then since the landing counts as one of the treads; I divided the rise by 14 which give me a riser height of 5.57”.

I also counted steps made on level ground over the same distance as the length of the stair and came up with 12 so I think 14 is conservative considering the slope but about right for my needs. I am not in a hurry to build but before I do I would still like to hear a professional opinion or two on this. Another possibility might include a landing midway up thus making all the treads shorter? Your input is appreciated.

Reply: stair design basics: calculating step riser height, step tread depth, total rise, total run, intermediate platform lengths

Tom,

I think a sketch of what you're up to would be helpful - if you want to send one use the CONTACT US link at page top/bottom. Meanwhile I'll provide two of my own: a "theoretical stairway" and then the "actual calculated stairway" at the end of these notes, based on the figures you provided.

Please see the details about how to calculate step or stair rise & run over at Stair Rise & Run Calculations where we discuss this topic nearly to death.

 

On 2014-06-02 by K. - steps or rails between rooms with floors at different heights ?

What about two rooms that are at different heights, so there is a single "step" up about 4". Any requirements for safety?

On 2014-06-02 - by (mod) -

K.

You want visual cues to call attention to the step, such as color differences on the two floors and perhaps a color difference on the face of the riser.m. That's my opinion, not a code citation.

On 2014-05-25 by sinees7@yahoo.com - can first step be smaller in height ?

can first step be smaller in height than the balance of the stairs (nj building codes)

On 2014-05-27 - by (mod) -

Sinees

NO - variation more than 0.375 inches ibetween successive stepr riser heights would be a trip and fall hazard.

 

On 2014-02-21 by isibro o ochoa - how fast does a body fall when falling down stairs?

my question is how fast would i be going before i hit the floor if i fell down a stairway approximatly four steps to the bottom which would be 32 inches.and land on my shoulder

On 2014-02-23 - by (mod) -

Isibro, that's an interesting question and I have no doubt that an attorney can find someone who will come up with a calculated number based on simple physics and terminal velocity but IMO the number would be rather unreliable considering that there are some most liklely unknown but important factors involved:

whether or not a person attempted to interrupt a fall, directions of movement: forward vs vertical, actual distances between the person's shoulder at the start of the fall and the end of the fall - which is almost certainly not the simple step height.

One also must know how far the person (or shoulder traveled AFTER the point of impact.

You can hop over to a physics site where many of them give a nice online calculator for "Impact Force from Falling Object" if theory rather than actual impact force is what's of interest. It's not the approach I would take.

...

Continue reading at STAIR RISER SPECIFICATIONS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• STAIR RISE & RUN CALCULATIONS
• STAIR DIMENSIONS, WIDTH, HEIGHT
• STAIR CODES & STANDARDS - home
• STAIR CODE DETAILS
• STAIRS, RAILINGS, LANDINGS, RAMPS - INSPECTIONS, CODES.
• Or see the ARTICLE INDEX below for detailed articles on specifications for proper dimensions for stairs, railings, platforms

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STAIR RISER HEIGHT FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to STAIRS RAILINGS LANDINGS RAMPS

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