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Stair dimensions (C) Carson Dunlop Associates Stair step height FAQs

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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 Carson Dunlop Associates.



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Stair Riser Height & Code FAQs

Undersized stair tread depth (C) Daniel Friedman

Questions & answers about stair riser heights and stair design, posted originally at STAIR RISER SPECIFICATIONS

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 2017-10-09 by Freddy

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

On 2017-10-05 by Steph

Say I have a deck that the height doesn't really work out for the rise to work out evenly on all my steps. According to code could I make me bottom step have a shorter rise to make up the difference?

On 2017-09-10 by Robert leite

What is the correct depth to a step off a deck 16 inches from the ground

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 2017-04-22 by Anonymous

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 2017-04-18 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.

Janet:

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 http://inspectapedia.com/Stairs/Stair_Calculations.php you will find this subtopic CALCULATE STEP TREAD DEPTH http://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 http://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 2017-02-05 by Jane

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

On 2017-01-28 by janet r ford

I have 17 1/2 inches to my room. Can the first riser be 10" and the second 7"? Or a combination where the first riser is higher than the second riser? thank you

On 2017-01-24 by Anonymous

There is a 9 inch step and threshold to get into my building. Nothing to pull myself in with but reaching for the doorway. I am legally disabled. What can I do

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.

On 2017-01-11 by Anonymous

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

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 2016-06-15 by Mr T

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 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 2015-11-19 by Tom

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

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.

On 2015-11-12 by Anita Chapman

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?

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.

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.

...


Continue reading at STAIR RISER SPECIFICATIONS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see STAIR TREAD DIMENSIONS

Or see STAIR DIMENSIONS, WIDTH, HEIGHT

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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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