Building Code Rules & Installation Specifications for Guardrail Cables: Wire Rope Railings
CABLE RAILINGS & GUARDRAILS - CONTENTS: What's a cable or wire rope railing? What's the difference between a guardrail and a handrail? Specifications for Installing Cable-Type Guard Railings along Balconies or Stairways. Cable Railing Specifications: railing height, cable diameters, cable spacing, cable support & cable tensioning. Maximum Sphere Passage Rule vs. Cable Type Guardrails & Stair Rails - Importance of Proper Cable Railing Spacing, Tension & Cable Railing Rigidity. The Ladder Effect of Horizontal Cable Railings - climbing children & Safety Issues
POST a QUESTION or READ FAQs about Building Code Rules & Installation Specifications for Guardrail Cables: Wire Rope Railings, spacing, tensioning, support, cable diameters, inspection, safety hazards, applications, & code approvals
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Guide to cable railings or wire rope guardrails: this article describes and includes illustrations of cable or wire rope railings or guardrails used along decks, balconies, walkways and stairways. We include definitions of guardrail, a handrailing or stairway handrail, nad other terms that assist in understanding the building code, construction, and safety requirements that wire cable type railings must meet.
We describe the key installation features necessary for cable railings and we explain both the 4-inch sphere rule problem faced by cable railings and the ladder-effect or climbability problem that these systems must also address. Installing a cable railing according to the manufacturer's specifications for spacing, tension, support, and other parameters (described here) improve the safety of cable railings.
Where the presence of children argues against any sort of horizontally-run guard railing member, cable railing manufacturers can provide vertical cable railing designs.
Building Code & Manufacturer Specifications for Cable (Wire Rope) Used in Stair & Guardrail Installations
What's a Railing? What's the difference between a guardrail and a handrail?
While cable "railings" are permitted under some building codes and by local building Inspectors we find that people speak a bit loosely about the definition of
"railing" - and "cable railing".
It is important to be clear in our terminology as building codes specify different requirements for handrailings than for guardrailings in terms of construction, height, and graspability. 
Definition of Guard railings
Properly, questions about cable railings or wire rope rails are asking about a guard rail, a type of safety "fencing" or "railing" used along the outer side of balconies
and stairways, not a "hand railing". Below in this article we discuss the installation and safety of cable-type guardrailings.
Our photo at left illustrates a home-made (and unsafe) cable guardrailing around the top of a stairwell opening in a New York home inspected by the author. The cables were visibly slack, incomplete, and the entire assembly so wobbly that it would easily collapse if leaned-on or stumbled-against.
A handrail is a horizontal or sloping rail intended to be grasped by a person's hand for support when using a stairway and
importantly, instinctively grasped in an attempt to arrest a fall.
Our photo (left) illustrates use of a wire cable "hand railing" along steps ascending the Pyramid of the Sun outside Mexico City.
Watch out: A wire rope or wire cable in the typical dimensions used at railings (1/8-inch to 3/8-inch in diameter) is not a graspable handrailing by any of the building code standards because of its small diameter.
1003.3.3.11.3 Handrail grasp ability. Handrails with a circular cross section shall have an outside diameter of at least 1.25 inches (32 mm) and not greater than 2 inches (51 mm) or shall provide equivalent grasp ability. If the handrail is not circular, it shall have a perimeter dimension of at least 4 inches (102 mm) and not greater than 6.25 inches (159 mm) with a maximum cross-section dimension of 2.25 inches (57 mm). Edges shall have a minimum radius of 0.125 inch (3.2 mm). - 2000 BOCA, ICBO, SBCCI
See HANDRAILS & HANDRAILINGS for details about hand railing building codes, construction, inspection, & safety concerns.
Specifications for Installing Cable-Type Guard Railings along Balconies or Stairways
If you take a look at cable "railing" specifications provided by a company that sells components
for cable railing construction [such as Atlantis Rail, Keuka Studios, or Wagner Companies, three suppliers of cable railing systems, you'll see that the "railing" is really a guardrail comprised of
stainless steel horizontal cables of diameters of 1/8", 5/32", 3/16", and 1/4" depending on the application.
Horizontal cables are
stretched tight, 3" o.c. to form a barrier and are supported by a combination of structural posts and intermediate posts spaced 42" o.c.
to 48" o.c. depending on the manufacturer's recommendations.
Wire Rope or Cable Guardrail / Railing Height - Balconies & Walkways vs Stairs
The International Residential Code (IRC) requires a minimum 36-inch-high guardrail for all decks, balconies, or screened enclosures more than 30 inches off the ground. 
The guardrail top height is in most jurisdictions 36" high (or more) in residential applications and 42" high in commercial installations. Along a stairway the railing height is governed by different rules because of the need to grasp the railing during use of the stairs.
Handrails are required on all stairs more than four risers in height. Handrails cannot be less than 30 inches nor more than 42 inches above the nosing of the treads
Maximum Sphere Passage Rule vs. Cable Type Guardrails & Stair Rails - Importance of Proper Cable Railing Spacing, Tension & Cable Railing Rigidity
For child safety, the balusters or other decorative infill must be spaced less than 4 inches apart (a 4-inch-diameter ball should not pass between the balusters). 
Companies selling cable guardrailings point out that building codes (IBC and IRC) specify that the opening between vertical balusters or between
horizontal railings (if the local code official will permit them) must be close enough together that a 4-inch sphere won't pass
between them. 
For horizontal cables we point out that if the cable can be stretched or is not properly tensioned, the guardrail system may
fail this 4-inch sphere test.
Also the largest opening between the bottom-most horizontal cable or guardrail member and an individual stair tread
should not pass a 6-inch sphere.
Cable or Wire Rope Spacing & Tension Are Critical for Safe Guardrails
Our photo (left) shows an attractive railing with horizontal cables intended to permit a nice view of the Brooklyn NY skyline.
We also demonstrate how easily the cables can be separated as well as how attractive this guard railing is to children.
To have a chance of meeting the 4" sphere rule (maximum sphere passage <= 4 3/8") the cables must be installed with adequate tension and rigidity to prevent deflection by
climbing or playing children or other forces that might be anticipated.
If the cable spacing is more than 3" o.c.) or the cable horizontal span is too great, if the intermediate posts spaced too
far apart (more than 42" of horizontal distance o.c.), or if the cables are not adequately tensioned, the system may fail this
safety test. Using a heavier gauge cable (3/16" diameter instead of the minimum 1/8" diameter) can also add
The supporting structural posts and intermediate bracing also need to be strong enough to handle the forces created by properly
tensioned horizontal cables. Wagner points out that
An incredible amount of tension is generated on an end post when you have ten or more lines, each tensioned at 400 lbs. over a height of 36" to 42". Often designers and fabricators inexperienced in cable railings will not recognize the amount of the tension applied to the posts.
The end result all too often is end posts which will bend considerably as the cables are being tensioned…or with a railing where the cables cannot be properly tensioned without an unacceptable amount of post deflection. The posts to which hardware is mounted must be constructed so that they will not deflect perceptively as the cables are tensioned.
And where we have seen
cable "guardrailings" installed, indeed a graspable and solid top rail was always provided. The top rail also provides a rigid
horizontal support that prevents the whole system from collapsing as vertical posts would bend inwards as the horizontal
cables are tightened.
Also, regular inspection of the tension and security of the cables is something I'd recommend, particularly in public
areas where the system may be subjected to climbers and pushers.
At left we illustrate that these horizontal cables were very resistant to opening, and considerable force was required to cause enough deflection to pass a 4-inch sphere. Notice that a heavier gauge cable diameter was used (3/8"), adding to the cable rail's rigidity.
Atlantis points out that using a cable tensioner such as their RailEasy™ device permits on-site cable cutting to proper length and
adjustment to proper tension without risking slack sagging cables due to mis-cuts or mis-measurement. The company also
describes the proper order of tightening the tension on the horizontal cables, starting at the center cable and then
alternating above and below that point as each cable is tensioned. 
The Ladder Effect of Horizontal Cable Railings - Safety Issues
Our concern with any horizontally-run guardrail structure is that it is climbable, and also that often we find the cables are loose
enough that a child can easily slip between the cables - an installation or maintenance error, not a conceptual error.
and opening of horizontal guard cables can be minimized by placing intermittent posts at suitable intervals between the supporting
posts. Atlantis suggests no horizontal space between posts should be 4 feet on center - a spacing that I usually see has been
violated by the installer.
At least some of the cable railing suppliers offer vertical cable railings for installations where a horizontal railing is not
approved or not suitable.
In our OPINION, a vertical cable guardrail adequately addresses the climbability question (the ladder effect)
and if properly tensioned, might pass the opening spacing requirements.
The Atlantis company's opinion is that because of their small diameter and lack of rigidity, horizontal cables are thin and not easy to climb.  Indeed in our photo where kids were tugging on the horizontal cables installed in a cable railing in New York City, the cables appeared rigid enough that there was not much visible deflection.
Our field experience is that children enjoy climbing horizontal cables and other horizontally run guardrailings. Perhaps due
to playground practice, it's apparent that kids have little difficulty ascending the cables. OPINION: We do not recommend any type of horizontal guardrail intermediate members that can be climbed in locations where children may be present.
Stairway handrail & stair balusters & guard details are in this sketch.
Balusters (vertical posts comprising the barrier in guards and railings)
Baluster opening between vertical members (maximum sphere passage <= 4 3/8")
Baluster opening in triangular area below guard bottom rail and stair tread (maximum sphere passage <= 6")
Hand-railing heights are given:
U.S. handrails for stairs with one side against a wall: 30-38"
U.S. handrails at open stairs: 34-38" above the stairs
Canadian stair handrails: 32-36" above the stairs
Wall clearance: Handrails along a wall must have at least 1.5" of clearance between the inside surface of the rail and the wall surface.
Railings should not project into the required width of the stairway by more than 4.5" at or below the handrail height above the stairs.
Question: what building codes regulate the use of cables on guardrailings?
The stainless steel cables are used in commercial, what's the IBC on cables in guards? - Scott Emerson 8/18/12
Thanks for the question, Scott. We do find both horizontal and vertical cable guardrailings installed in commercial locations such as the shopping center shown in photos earlier on this page, but ultimately the approval is up to local code enforcement officials. As for specific code requirements, the railings have to pass the same height, strength, spacing, and graspability rules as other types of railings. Please take a look at the article above and also see references  and let me know if questions remain.
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 §3209. Standard Guardrails, California Building Code, provides description of how guard rails should be constructed. Web search 09/02/2011,original source: www.dir.ca.gov/title8/3209.html
 "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 email@example.com 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
Atlantis Rail, division of Suncor Stainless, Inc.,
Atlantis Rail Systems
70 Armstrong Road
Plymouth, MA 02360
Toll free: 800-541-6829
 The Wagner Companies
0600 West Brown Deer Rd.
Milwaukee, WI 53224
 Keuka Studios:
1011 Rush Henrietta Town Line Rd.
Rush, NY 14543
Phone: Toll Free (855) 454-5678
Main: (585) 487-6148
Fax: (585) 487-6150
 Building Code Rules for Stair Rail Cables - Wire Rope Guardrails & Stair Railings
UBC 1003.3.3 1997
 The International Building Code (IBC)
International Residential Code (IRC)
 ISO 9001:2008
 1003.3.3.11.3 Handrail grasp ability. Handrails with a circular cross section shall have an outside diameter of at least 1.25 inches (32 mm) and not greater than 2 inches (51 mm) or shall provide equivalent grasp ability. If the handrail is not circular, it shall have a perimeter dimension of at least 4 inches (102 mm) and not greater than 6.25 inches (159 mm) with a maximum cross-section dimension of 2.25 inches (57 mm). Edges shall have a minimum radius of 0.125 inch (3.2 mm).
 BOCA National Property Maintenance Code 1993:
PM-305.5 Stairs and railings: all interior stairs and railings shall be maintained in sound condition and good repair.
Commentary: Handrails, treads and risers must be structurally sound, firmly attached to the structure, and properly maintained to perform their intended function safely. During an inspection the code official should inspect all stringers, risers, treads, and handrails.
PM-305.6 Handrails and guards: Every handrail and guard shall be firmly fastened and capable of supporting normally imposed loads and shall be maintained in good condition.
Commentary: This section provides for the safety and maintenance of handrails and guards. See Section PM-702.9 for additional requirements.
PM-702.9 Stairways, handrails and guards: Every exterior and interior flight of stairs having more than four risers, and every open portion of a stair, landing or balcony which is more than 30 inches (762mm) high, nor more than 42 inches (1067mm) high, measured vertically above the nosing of the tread or above the finished floor of the landing or walking surfaces. Guards shall be not less than 30 inches (762mm) high above the floor of the landing or balcony.
Commentary: Handrails are required on all stairs more than four risers in height. Handrails cannot be less than 30 inches nor more than 42 inches above the nosing of the treads (see Figure PM-702.9).
Guards are required on the open side of stairs and on landings and balconies which are more than 30 inches above the floor or grade below. The guard must be at least 30 inches above the floor of the landing or balcony. Guards are to contain intermediate rails, balusters or other construction to reduce the chance of an adult or child from falling through the guard. If the guard is missing some intermediate rails or balustrades, it is recommended that the guard be repaired to its original condition if it will provide protection equivalent to the protection it provided when originally constructed.
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