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Questions & answers about stairway dimensions, stair clearances, headroom, codes.
Here we answer frequently-asked questions about the required dimensions and clearances for exterior or interior stairs.
This article series provides the stair dimensions required by building code specifications and includes sketches, photographs, and examples of defects used in inspecting indoor or outdoor stairs, railings, landings, treads, and related conditions for safety and proper
On 2017-04-15 21:01:05.233274 by (mod) re: adding a nose to existing stair treads?
Thanks for the comment, Larry.
I'd worry that an added-on stair tread nose may create an unsafe walking edge - breaking away - unless it's rabbeted or otherwise very securely connected to the tread. Lots of work. I'd be tempted to just replace the treads.
On 2017-04-15 03:27:57.249619 by larry lemire
tried to correct a set old of stairs adding another 1 ' to tread nosing on dont do this its thes same thing
On 2017-04-10 15:35:51.501933 by (mod) re: list all of the ways that stairs must comply with laws?
You might want to check the article index for stairs given at the end of this article. There you'll find a very extensive list of stair specifications as well as citations from multiple stair building codes.
You need to determine the type of stairs you are building and then to review the building code specifications.
On 2017-04-10 12:31:22.996166 by atumanyire bylon
cant you list for me the conditions to be considered when constructing stairs so as to comply with the by law?
On 2017-04-10 12:30:57.065850 by Anonymous
can't you list for me the conditions to be considered when constructing stairs so as to comply with the by law?
On 2017-02-25 15:33:07.748559 by (mod) re: Can I build a new 29" wide stairway
The stair has to fit in the available space but also needs to have safe width and tread dimensions, headroom, etc. Often a turn in the stairway can solve some of the fit problems;
On 2017-02-23 21:14:10.372524 by Jake
Hello, I have a question. I live in Michigan, my house was built in 1976, the basement stairway is in bad shape and I need to replace it. However, due to space constraints I need to build a 32" wide stairway (29" with tread, 10" deep) is this possible, acceptable, or allowable? Your input will be really appreciate it. Thanks
On 2017-02-16 22:18:16.585939 by Gerry
Thank you that's what I was thinking
On 2017-02-14 01:53:53.648977 by (mod) re: moving a basement door onto steps - angling steps for a turn
Sorry Gerry- so many readers that sometimes we get behind in replying to comments. I'm not sure what specifics I can add as you already understand the math.
You cannot force both rise and run if they do not accomodate a step riser height and tread depth that is safe to walk upon. Typically that's a 10-11" deep tread and a rise around 7".
I would calculate the number of steps (42/7=6) and the run (6 x 10 = 60) to show that you cannot fit a run that's half that length.
Sometimes, if there is headroom over the landing, you can build stairs with a turn, as you suggest, but I'd prefer to see rectangular steps and a square landing - far less trip prone.
On 2017-02-08 01:18:51.888994 by Gerry
I moved a basement door on steps that weren't done properly to begin with.
The rise is 42 inches run is 30 inches at the top step door is on the left so will need angled steps for the turn. how many steps do I need. I'm pretty sure I can figure the math out and angles that will work after that, but any additional help would be appreciated. Thank you in advance
On 2017-01-26 14:16:10.392399 by (mod) re: will the stairway width be considered too small when I add handrailings?
Sorry but I don't quite understand the question. I don't know what slipping the distance means.
But at the end of the day the answer to this question lies with your local building department.
You might want to ask them to take a look at the hallway and the stairs and to tell you what they will accept.
Often a local building department is not going to require extreme modifications to a building and they may give you a grandfather clause that allows your Stairway to be more narrow than the modern standards.
On 2017-01-26 03:26:42.594350 by Mike
I am replacing my narrow interior steps in my old house built in the 1920s if i i follow the minimum required code of 36" wide on the steps my hallway will become to narrow at 32"wide. am i allowed to slip the width right down the middle so my steps and hallway width are equal?
On 2016-08-07 16:03:58.682735 by (mod) re: central handrail on wide stairs
Yes Donald in that wider stairways, depending on where you live and what building codes apply, may require handrails on both sides of the stairway. And of course all open stairs need guards on both sides.
There are not standards or codes that support the complete omission of handrailings on ordinary-use stairways.
On 2016-08-06 19:44:16.411336 by Donald Groden
Is there a code requirement for the insulation of handrails to be determined by the with of the stairs ?
Question: elevated salon chair steps
(Dec 28, 2011) Richard said:
I want to build a box on the floor of my hair salon to elevate a chair which will be put on top the box. The box will be about 42" x 64". I want to make it about 8" higher than the floor. It will be in a traffic area.
I have tried to research the New York State building codes on line but can find no reference to start. Is it a step? or stair? or landing? or platform? or uneven floor? Its just a box on the floor but it must have a name in the codes. Will it need railing? or noseing or edging? or a distinctive something so people dont fall (trip) over it? Any advice and direction to code #'s will be appreciated. Thank you very much
Richard that's a new one for me, and I have not found a code citation for elevated salon chairs. Because the local building code inspector has the final authority, I'd give them a call and ask for advice. I've found that the folks in the building department are very helpful when they see that someone wants to do right rather than trying to get over on the inspector.
Question: how to build stairs using concrete blocks
(July 17, 2014) Alan James said:
i want to build stairs using 16 inch X 4 " X 8" concrete blocks. The run is 416 inches and the rise is 259 inches. By using the formula i get a 8.9 inch rise for each step. Is this legal and if not how do I make the stairs??
8.9 inches is too much rise per step. You'd need to extend the horizontal run and add steps to lower the individual rise or add a platform or landing to achieve the same. I think in general if you are using 4" (thick" blocks you're in trouble if your step plan calls for using pairs of them per step as the steps will be too high.
Question: Do exterior contrete stairs leading to two terraces apartments have to be a certain width?
(Feb 11, 2015) Do exterior contrete stairs leading to two terraces apartments have to be a certain width? One owner wishes to put in chairlift up side of staircase railing. Stairs are 84cm wide. said:
Do exterior contrete stairs leading to two terraces apartments have to be a certain width? One owner wishes to put in chairlift up side of staircase railing. Stairs are 84cm wide.
(Nov 3, 2014) carmel fennessy said:
oueurn but not a spiral thank youstion can i fit a 32 inch wide staircase into a space 60x60x96 with a platforn and t
Stairway width (in the U.S. - you don't say where you are located) should be equal to or greater than 36" of clear unobstructed distance measured at all points above the [permitted] hand-railing height.
84cm stair width, assuming that's the unobstructed width, is 33" or already less than the 36" recommended.
For an example building code pertaining to chair lifts and wheelchair lifts I look at ASME A18.1- 2003, Safety Standard for Platform and Stairway Chairlifts
Also see California's Subchapter 6. Elevator Safety Orders
Group 2. Existing Elevator Installations, Article 15. (a) Inclined stairway chairlifts shall comply with ASME A17.1-1993, Section 2002, Inclined Stairway Chairlifts, which is hereby incorporated by reference, except Rule 2002.10a and Rule 2002.10c(2).
NOTE: The installation of all inclined stairway chairlifts are subject to local building codes, fire regulations, and contractors licensure.
(Title 24, Part 7, Section 7-3094.4)
NOTE: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code; and Section 18943(b), Health and Safety Code.
In my OPINION the standards and model codes give some leeway to the LOCAL building code official (who's final word is law) to accept a narrowing of the stairway to provide for the inclined stairway lift installation, provided that means of egress for walking residents is not unduly hampered.
From the ASME standard I excerpt: "Lifts shall be installed so that means of egress is maintained as required by the authority having jurisdiction. "
Different rules may pertain for private residences than public buildings.
Question: inadequate headroom at apartment building stairs
(Apr 9, 2015) Concerned said:
My apartment building has decided to bump out a unit that is above a set of stairs. After they added the new wall and floor, my friend who is 6''1' tall now has to bend his neck or back to get down the stairs so he does not hit his head.
There is also no visible permit for this addition and I am not sure if anyone even came to my apartment building to tell the landlord that this is okay. Surely my friend is not the only tall one, and what if there is an emergency and he forgets to bend over and he winds up smacking his head on this new "wall" and hurts himself? Though it is a smaller stairwell, it is the one that is used most.
What do I do about all of this and who do I talk to? I feel that this is unsafe construction just to add a little more room to an apartment that may not be necessary but simply wanted by the landlord. In addition, if someone does hit their head going up or down the stairs and falls to the point of injury, are the building owners at fault?
Certainly there are building codes and standards for safe passage on stairways, including headroom (See STAIR HEADROOM in More Reading just above).
It sounds as if modifications to the building or stairway were made without proper inspections & permits and that they are likely to be improper and unsafe. If your building management is not responding to your written concern your next recourse is to ask your local building department for help.
Question: can stair width change ? San Francisco Stair Code.
(Apr 15, 2015) Narrow Stair said:
I understand the minimum stair width in my area (San Francisco) is 36". Can I have the upper run of an L-shaped stair be wider, say 42", and have the lower run narrow down to the code minimum 36"? In other words, the stair gets narrower in the direction of egress, but not below code minimum.
What an interesting question. I don't know. This funneling-stair-design is not a design I've come across previously. It is possible that your local building department would approve your stair funnel in a private residence, but in my OPINION it would be unsafe in a public building where during an emergency a crush might develop at the reduction in width.
Let me know what your local code official says.
Question: 8 1/2" tread depth stairs are too small
(Dec 3, 2015) Dan said:
I live in a apartment hous. It has 18 stairs to my upper room. They measure 8.5 inches per board. I wear a size 12 shoe and wondering if they are legal. I know there dangeros.
(Jan 22, 2016) Julio said:
are Stairs that are 1/4 or 1/2 shorter in height acceptable, if so what literature can I use
Depending on where you live stair codes may vary but typically you are allowed up to 3/8" variation in riser height, or quoting:
Step riser height uniformity (<= 3/8" variation)
so 1/2" is a trip hazard. you can print this page or you better you can check with your local building department to obtain a copy of the code that applies where you live. >
Question: stair width vs building occupancy
(Feb 26, 2016) Anonymous said:
how wide does a stair needs to be if occupancy is greater than 50
I don't know and don't have that specific reference; check with your local building department. let me know what you're told.
Question: steps to climb an 11" total rise
(Apr 12, 2016) Jerry said:
I have an 11 inch drop from a side exterior door of my house. Should I build a single concrete step: a) 7 inches height, b) 4 inches height, or c) something in-between?
One 11 inch step, we both agree is too tall.
But two steps of different rise are also unsafe - a trip hazard.
All of your riser heights should be the same. To me that suggests two risers of 5 1/2" - with an increased tread depth, since short riser stairs are more comfortable and safe to walk up and down if the treads give more walking space.
For a complete list of articles on stairs, railings, and ramps, their inspection, trip hazards, and good design,
see STAIRS, RAILINGS, LANDINGS, RAMPS - INSPECTIONS, CODES. Or see these detailed articles on specifications for proper dimensions for stairs, railings, platforms
Continue reading at STAIR DIMENSIONS, WIDTH, HEIGHT or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
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Eric Galow, Galow Homes, Lagrangeville, NY. Mr. Galow can be reached by email: email@example.com or by telephone: 914-474-6613. Mr. Galow specializes in residential construction including both new homes and repairs, renovations, and additions.
 "The Elimination of Unsafe Guardrails, a Progress Report," Elliott O. Stephenson, Building Standards, March-April 1993
 "Are Functional Handrails Within Our Grasp" Jake Pauls, Building Standards, January-February 1991
 Access Ramp building codes:
 Access Ramp Standards:
ADA (Americans with Disabilities Act), Public Law 101-336. 7/26/90 is very often cited by other sources for good design of stairs and ramps etc. even where disabled individuals are not the design target.
ANSI A117.4 Accessible and Usable buildings and Facilities (earlier version was incorporated into the ADA)
ASTM F 1637, Standard Practice for Safe Walking Surfaces, (Similar to the above standard
 Falls and Related Injuries: Slips, Trips, Missteps, and Their Consequences, Lawyers & Judges Publishing, (June 2002), ISBN-10: 0913875430 ISBN-13: 978-0913875438 "Falls in the home and public places are the second leading cause of unintentional injury deaths in the United States, but are overlooked in most literature. This book is unique in that it is entirely devoted to falls. Of use to primary care physicians, nurses, insurance adjusters, architects, writers of building codes, attorneys, or anyone who cares for the elderly, this book will tell you how, why, and when people will likely fall, what most likely will be injured, and how such injuries come about. "
 The National Institute of Standards and Technology, NIST (nee National Bureau of Standards NBS) is a US government agency - see www.nist.gov
"A Parametric Study of Wall Moisture Contents Using a Revised Variable Indoor Relative Humidity Version of the "Moist" Transient Heat and Moisture Transfer Model [copy on file as/interiors/MOIST_Model_NIST_b95074.pdf ] - ", George Tsongas, Doug Burch, Carolyn Roos, Malcom Cunningham; this paper describes software and the prediction of wall moisture contents. - PDF Document from NIS
 Slips, Trips, Missteps and Their Consequences, Second Edition, Gary M. Bakken, H. Harvey Cohen,A. S. Hyde, Jon R. Abele, ISBN-13: 978-1-933264-01-1 or
ISBN 10: 1-933264-01-2,
available from the publisher, Lawyers ^ Judges Publishing Company,Inc., www.lawyersandjudges.com firstname.lastname@example.org and also from the InspectAPedia Bookstore (Amazon.com)
 The Stairway Manufacturers' Association, (877) 500-5759, provides a pictorial guide to the stair and railing portion of the International Residential Code. [copy on file as http://www.stairways.org/pdf/2006%20Stair%20IRC%20SCREEN.pdf ] -
 Mold-Resistant Building Practices, advice from an expert on how to prevent mold after a building flood and how to prevent mold growth in buildings by selection of building materials and by anti-mold construction details.
 "The Dimensions of Stairs", J. M. Fitch et al., Scientific American, October 1974.
 Stair & Walkway Standards for Slipperiness or Coefficient of Friction (COF) or Static Coefficient of Friction (SCOF)
ASTM D-21, and ASTM D2047
UL-410 (similar to ASTM D-21)
NSFI 101-B (National Floor Safety Institute)
NSFI Walkway Auditing Guideline (WAG) Ref. 101-A& 101-B (may appear as ANSI B101.0) sets rules for measuring walkway slip resist
OSHA - (Dept of Labor CFR 1910.22 does not specify COF and pertains to workplaces) but recognizes the need for a "qualified person" to evaluate walkway slipperiness
ADA (relies on the ANSI and ASTM standards)
 A. Sacher, International Symposium on Slip Resistance: The Interface of Man, Footwear, and Walking Surfaces, Journal of Testing and Evaluation (JTE), ISSN: 1945-7553, January 1997 [more focused on slipperiness of polished surfaces
 Algae is widely recognized as a slippery surface - a Google web search for "how slippery is algae on steps" produced more than 15,000 results on 8/29/12)
 Slipperiness of algae on walking surfaces, warning, Royal Horticultural Society, retrieved 8/29/2012, original source: http://apps.rhs.org.uk/advicesearch/profile.aspx?pid=418
 Slipperiness of algae: "Watch your step, wet rocks and algae are slippery" Oregon State University warning 1977 retrieved 8/29/2012, original source: http://www.worldcat.org/title/watch-your-step-wet-rocks-and-algae-are-slippery/oclc/663683915
 Coefficient of friction of algae on surfaces [like stair treads]: Delphine Gourdon, Qi Lin, Emin Oroudjev, Helen Hansma, Yuval Golan, Shoshana Arad, and Jacob Israelachvili, "Adhesion and Stable Low Friction Provided by a Subnanometer-Thick Monolayer of a Natural Polysaccharide", Langmuir, 2008 pp 1534-1540, American Chemical Society,
retrieved 8/29/2012, Abstract: Using a surface forces apparatus, we have investigated the adhesive and lubrication forces of mica surfaces separated by a molecularly thin, subnanometer film of a high-molecular-weight (2.3 MDa) anionic polysaccharide from the algae Porphyridium sp. adsorbed from aqueous solution. The adhesion and friction forces of the confined biopolymer were monitored as a function of time, shearing distance, and driving velocity under a large range of compressive loads (pressures). Although the thickness of the dilute polysaccharide was <1 nm, the friction was low (coefficient of friction = 0.015), and no wear was ever observed even at a pressure of 110 atm over 3 decades of velocity, so long as the shearing distances were less than twice the contact diameter. Atomic force microscopy in solution shows that the biopolymer is able to adsorb to the mica surface but remains mobile and easily dragged upon shearing. The adhesion (adsorption) of this polysaccharide even to negatively charged surfaces, its stable low friction, its robustness (high-load carrying capacity and good wear protection), and the weak (logarithmic) dependence of the friction force on the sliding velocity make this class of polyelectrolytes excellent candidates for use in water-based lubricant fluids and as potential additives to synovial fluid in joints and other biolubricating fluids. The physical reasons for the remarkable tribological properties of the ultrathin polysaccharide monolayer are discussed and appear to be quite different from those of other polyelectrolytes and proteins that act as thick “polymer brush” layers.
 Jason R. Stokes, Lubica Macakova, Agnieszka Chojnicka-Paszun, Cornelis G. de Kruif, and Harmen H. J. de Jongh, "Lubrication, Adsorption, and Rheology of Aqueous Polysaccharide Solutions, Langmuir 2011 27 (7), 3474-3484
 "Coefficients of Friction for Ice", The Physics Factbook™, Glenn Elert, Ed., retrieved 8/29/12, original source: http://hypertextbook.com/facts/2004/GennaAbleman.shtml
 "Coefficients of Friction for Ice", The University of the State of New York Reference Tables for Physical Setting/Physics. New York: The State Education Department, 2002. Op. Cit.
 Serway Physics for Scientists and Engineers 4th edition (p. 126.)
 "How Slippery Is It", retrieved 8/29/12, original source http://www.icebike.org/Articles/howslippery.htm
 John E. Hunter, "Friction Values", The Source, Society of Accident Reconstructionists, Winter 1998. Study of frictional values of car tires involved in collisions on snow or ice covered roadways.
 Frictional Coefficients of some Common Materials and Materials Combinations, The Engineering Toolbox, retrieved 8/29/2012, original source: http://www.engineeringtoolbox.com/friction-coefficients-d_778.html [copy on file as Friction and Coefficients of Friction.pdf ]
 Stairways and Ladders, A Guide to OSHA Rules, OSHA, U.S. Department of Labor, 3124-12R 2003 - Web Search 05/28/2010 original source: http://www.osha.gov/Publications/osha3124.pdf. OSHA regulations govern standards in the construction industry and in the workforce Quoting from OSHA whose focus is on workplace safety and so excludes discussion of falls and stair-falls in private homes:
OSHA estimates that there are 24,882 injuries and as many as 36 fatalities per year due to falls from stairways and ladders used in construction. Nearly half of these injuries are serious enough to require time off the job--11,570 lost workday injuries and 13,312 non-lost workday injuries occur annually due to falls from stairways and ladders used in construction. These data demonstrate that work on and around ladders and stairways is hazardous. More importantly, they show that compliance with OSHA's requirements for the safe use of ladders and stairways could have prevented many of these injuries. -osha.gov/doc/outreachtraining/htmlfiles/stairlad.html
 International Building Code, Stairway Provisions, Section 1009: Stairways and Handrails, retrieved 8/29/12, original source: http://www.amezz.com/ibc-stairs-code.htm [copy on file as IBC Stairs Code.pdf]
 Model Building Code, Chapter 10, Means of Egress, retrieved 8/29/12, original source: http://www2.iccsafe.org/states/newjersey/NJ_Building/PDFs/NJ_Bldg_Chapter10.pdf, [copy on file as NJ_Bldg_Chapter10.pdf] adopted, for example by New Jersey. International Code Council, 500 New Jersey Avenue, NW, 6th Floor, Washington, DC 20001, Tel: 800-786-4452
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