Stair Tread Width & Stair Tread Nose Construction Details

Stair tread width & nosing design specifications & codes
- Stair tread width or dimensional specifications
- Stair Tread nose shape & size specifications
- Stair Tread Width Requirements Vary by Open or Closed Stairway Risers
- Stair Step Tread Nose Projection Requirements & Stair Code Citations
- Photographs & Sketches of Stair Tread Defects
- Stair Tread Defects: too narrow tread width, too high tread riser, uneven tread risers
- Broken or Breakaway Stair Tread Nose Hazards & Their Contribution to Stair Falls
- Effects of Stair Tread Lumber Type & Preservative Treatments on Risk of Damage & Stair Falls
- Common causes of slippery stair treads, steps, or other outdoor walking surfaces
- Use of Color to Indicate Stair & Step Changes Can Reduce Trip & Fall Injuries
Stair dimensions: width height &c - separate article
STAIR HEADROOM - separate article
STAIR RISER SPECIFICATIONS - separate article
STAIR TREAD DIMENSIONS
Questions & answers on details about exterior stair tread dimensions, construction & related trip & fall safety hazards
References

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Stair tread & step construction details & code specifications: this document provides building code specifications for stair treads: sketches, photographs, and examples of defects used in inspecting the step design on indoor or outdoor stairs and their treads, including the requirements for a projecting stair tread nose and the tread nose shape and dimensions. We discuss the use of color or other visual clues to reduce trip & fall hazards. We also include references to key documents on building codes and stair and railing safety. Our photograph of badly worn stair treads (above) was provided courtesy of Carson Dunlop Associates.

Stair Tread Construction Dimensions, Specifications & Safety Defects

This article discusses stair tread depth, stair tread nose profile & dimensions or projection, and stairway width.

Undersized stair tread depth (C) Daniel Friedman

Stair tread dimensions tread nosings are detailed here. 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 in our list of Related Topics near the top of this page.

Definition of stair tread (tread depth)

The stair tread is the horizontal walking surface (red arrow) of an individual step. The tread depth is measured from the forward edge of the step nose or edge of the step above out to the leading edge of the step being measured - the space beneath my foot in the photo at left.

Stair tread depths shall be 11 inches (279 mm) minimum.

The stair tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at right angle to the tread's leading edge.

Stair risers: A stair riser is the vertical distance (green arrow) between the walking surface of two stair treads is the stair riser or riser height. Open riser stairs have no enclosure (my toe, shown below, would be facing into open space). Closed riser stairs (shown below) include a vertical riser board (that my toe is kicking against). Stair risers are detailed at Step riser dimensions.

Don't confuse step riser height (defined above) with stairway headroom - the vertical space between the walking surface of a stair tread and the ceiling or other obstruction overhead (defined further at STAIR HEADROOM).

Definition of Stairway Width or Stair Width - don't confuse stair width with stair depth

Stairway and stair tread width (C) Daniel Friedman

Watch out: it's confusing but many people refer to stair tread depth as stair step or tread width, including our Canadian stair dimension illustration just below.

If you stick to using the word stair tread depth you can avoid this confusion. Oops, that is, unless you start confusing tread depth with stair tread riser height. Stair tread depth is defined above as the horizontal distance from nose to nose or from riser face to nose on open riser stairs.

Stairway width is the horizontal width of the stair opening (blue arrow in our photo). For stairs enclosed by a wall on both sides, usually the stairway width is the distance between those walls.

Stair tread width (green arrow in our photo) is the horizontal left to right width of the stair tread.

At left our photo illustrates three different stair width measurements

Stair tread width (green arrow) (smaller than stairway width due to side trim boards)
Stairway width (blue arrow) over most of this stairway (nominally 36")
Stairway width near stair top (pink arrow) due to a wall projection (nominally 35")

Stair Tread Depth (Width) Requirements Vary by Open or Closed Stairway Risers

Stairway Lighting requirements (C) Carson Dunlop

Closed stair treads using a solid riser are shown at the left of the sketch and open stair treads are shown at the right sketch.

Notice that the minimum stair tread thickness is increased when the stair tread is not supported by a solid riser.

Note that some of these dimensions pertain to Canadian building codes. U.S. stair codes and OSHA stair specifications may vary. See details on tread specs also found at STAIRS, RAILINGS, LANDINGS, RAMPS

Sketch courtesy Carson Dunlop Associates.

Stair Step Tread Depth, Uniformity & Slope Specifications

Damaged stair treads (C) Daniel Friedman

Step tread depth (=> 10") (measured 12" from smaller side of irregular stair shapes such as triangular treads on curves or spirals)
Step tread depth uniformity (<= 3/8" variation)
Stair tread depth for winder stairs (>= 6" at smallest point)
Stair tread uniformity for winder stairs at the 12" walk-line (<= 3/8" variation)
Stair tread slope (out of level on walking surface) - (slope or "rise" must be <= 1 in 48) -- Source: IRC

The stair treads shown in our photo are very dangerous not only because they are pitched and loose, but because there is danger of stairway collapse.

The tread slope and collapse risk are visually obvious. The stair inspector should be asking: "What caused this weird movement and who made these goofy repairs?" and "What other work did that person perform on this building?"

Stair Riser Height & Stair Tread Depth Dimensions - Example from BOCA Code 2001

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

The riser height shall be measured vertically between the leading edges of adjacent treads.

Also see Step riser dimensions or Stair dimensions: width height &c
Stair tread depths shall be 11 inches (279 mm) minimum.

The stair tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at right angle to the tread's leading edge.

My foot illustrates a stair tread depth that is less than 11 inches - the boot toe is against the stair riser and the heel extends well past the stair tread nose.

Stair Step Tread Nose Projection Requirements & Stair Code Citations

Definition of stair tread or landing nose or nosing

The leading edge of treads of stairs and of landings at the top of stairway flights. - IBC 1002 [14a]

At left we illustrate stairs constructed with no tread nose projection - a common design in areas where stairs are often built of tile and masonry. These steps to include a nice color indication of the location of stair risers - but visible mostly to people ascending the steps. These steps were observed in Barcelona, Spain.

While a tread nose is not required on stairs with open risers, closed riser stairs like these should have a tread nose projection as specified below:

Tread nose projection past vertical riser below (3/4" to 1 1/2") required on stairs with solid risers (exceptions are below)
Tread nose projection uniformity (<= 3/8" variation)
Tread nose curve radius (=< 9/16")
Tread Nose not required if tread depth is => 11"
Tread Nose not required on open stair treads (open riser)

Another Stair Construction Code Example - BOCA 2001

Stair tread nose projection missing or wrong dimension: (falling hazard on descending) or tread nose extends out too far over tread (risk splitting off or trip especially on climbing up).

Example: A nosing not less than 0.75 inch (19.1 mm) but not more than 1.25 inches (32 mm) shall be provided on stairways with solid risers where the tread depth is less than 11 inches (279 mm). - BOCA 2001.

Broken or Breakaway Stair Tread Nose Hazards & Their Contribution to Stair Falls

The previously-hidden danger on the stair treads shown below was that someone, trying to make the stairs more safe, installed rubber stair tread covers that projected past a broken stair tread nose. The stair treads looked fine but someone stepping on the un-supported edge of the stair tread cover simply broke it away and fell down the stairs.

More than one of these rubber/plastic glue-on stair tread covers had a broken nose, probably because the stair tread "skins" were not properly trimmed and sized to fit the tread. If the rubber or plastic "safety tread" on the stair includes a rounded nose covering extension that is not supported by the actual stair tread nose beneath, breakaways like this are likely to occur.

Damaged stair tread nose (C) Daniel Friedman

How Does a Damaged Stair Tread Nose Contribute to a Fall?

Opinion: Daniel Friedman.

To understand the role of the nose or edges of stair treads and the importance of a secure stair tread edge that does not break or collapse, look closely at our photo at left. When ascending stairs and in some cases when descending stairs, the stair user naturally places their foot and their weight at the leading edge of each step - the tread edge or tread nose.

If that stair tread edge or nose is sloped, uneven, slippery, damaged, or worse, breaks during use, a fall is likely.

There are two distinct stair fall cases that may occur due to a defect in the nose or edge of a stair or platform or landing:

Intact stair tread nose breaks away

If a stair tread nosing is intact, that is in place, and if when a walker stepson the edge of the nosing that area breaks way under foot ,that event would be likely to cause or contribute to a stair fall. Tread nose breakaway fall accidents can occur in either ascent or descent of the stair though in my experience and opinion people are more likely to put weight on a stair nose during ascent than descent.

Previously broken stair tread nose uneven edges

If the tread nosing was already broken away that condition can still contribute to a fall, though more from the problem of the inconsistency of the tread nose edge - causing an angling of the foot and a possible slip, rather than causing a fall due to the suddenness of collapse of a breaking-away piece of the stair tread or landing supporting a person's weight.

If a building inspector observes damaged stair treads the stairs should be marked as unsafe and access restricted until a proper repair can be made.

The broken stair tread nosing photos above illustrate this hazard found in an art center in New York City - a public space. At above right you can see how a person climbing the stairs might place her weight on the edge of the stair tread nosing - in this case leading to a break and a possible stair fall. At above left you'll see some pretty nice handrails on both sides of the stairs - features that may help arrest a fall.

Effects of Stair Tread Lumber Type on Risk of Damage & Stair Falls

Opinion: Daniel Friedman.

Any broken away or uneven tread nose is a trip and fall hazard. A question sometimes arises about the role of choice of materials in the chances of a stair fall due to tread or tread nose breakage. Does the lumber type of species make much difference in this risk?

Possibly so insofar as treated wood Southern Yellow Pine lumber may present a greater chance of having a breakaway around knots than other choices such as cedar or even plastic wood deck & tread lumber materials.

Nevertheless, the decision to use treated lumber itself should have little useful bearing on a stair fall case as it's both common practice and in some regards is a safer choice to use treated lumber over non-treated pine or SPF since preservative treatments, by reducing the risk of structural rot, should make a wood stairway more durable and safer than more rot-prone choices. .

Most treated wood used in North America is Southern Yellow Pine (SYP) impregnated with preservative salts. The wood is often quite wet with preservative when purchased, it will even squirt when nailed. But since cessation of the use of more toxic wood preservatives (such as CCA), treated wood is not more inherently hazardous when you remove a piece of the tread nose than any other wood, with a small, weak, technical exception. SYP is generally a more knotty wood than some alternatives such as cedar decking.

A property of SYP is its inherent knottiness and tendency to warp. So depending on what alternative and more costly wood that might be use for decking, say cedar, there is a non-quantifiable greater chance that a knot appears at5 or close to the edge of a board and thus could end up on a stair tread nose.

The presence of a knot at the edge of wood used to build a stair tread produces a form of weakness of the wood in that area in that the weight of someone stepping on the edge of the tread nose might break the nosing away on either side of the knot. Openings around knots can also hold water and in a freezing climate an thus contribute to ice or frost cracking and damage to the wood in that area.

Breakaway on either side of a knot in the wood near the edge of the walking surface is what we observe in your video of the area of damaged tread nosing in your video. We haven't established if the break occurred at the time of the fall or prior to it, but I consider it most likely that at least part of the tread nose was broken away before the fall because I observe breakaway of several inches on both sides, left and right, of the knot - not something that would be likely to occur by a single event of a single foot pressure over that area.

Watch out: Builders constructing wooden stair treads using dimensional lumber or 5/4 lumber (deck boards) should take care that the nose of stair treads does not include knots or other damage that increase the risk of a future stair tread breakaway.

What about slipperiness of treated wood decks or stairs when wet? Is treated lumber more slippery than other decking?

More slippery than what?

The hardness of lumber species varies as does surface texture; cedar (used on more expensive decks, steps, rails) for example has a somewhat more grainy surface and may be less slippery than treated wood when dry.

But I doubt that a coefficient of friction of wet vs dry woods by species has much useful bearing on a stair fall case as it is absolutely standard common practice to use treated lumber on outdoor decks, balconies, stairs, and even railings and balusters.

The really horrible stairs in our photo (left) are installed at a Poughkeepsie NY home surrounded by shade trees. The 2x6 treads (actually 5 1/2" in depth) are exactly 1/2 of the recommended tread depth and are covered with algae that will be hysterically slippery when wet.

And the faux hand railing made of pipe extends just about 20 inches above the stair treads - not a usable rail height. These stairs are treacherous. But we find algal growth can occur on all species of wood used for exterior stairs as well as on some other surfaces, even concrete.

Details about algae, ice, snow, water and other slippery stair and walking surfaces are found at Slippery Stairs, Walks.

Impact of Post-construction Wood Treatments & Preservatives on Exterior Deck or Stairway Slip Hazards

There are other treatments that can be applied to outdoor wood decks, balconies, rails, such as preservative stains (recommended by manufacturers but not required by codes). Such preservatives or stains are used on both treated wood and also on cedar decking, and some paints are also used on synethetic decking. For wood surfaces these add-on products extend the life of the structure, improve its appearance, and many provide some water repellence to the surface - factors that further reduce the chances of formation of slippery algae on the walking surface.

These are the most common causes of slippery stair treads, steps, or other outdoor walking surfaces

Snow or ice in areas of freezing climates
Algal growth or on occasion fungal growth on the wood surface, largely affected by the presence or absence of sun exposure
Water improperly directed on the deck or stair surface due to mis-routing of roof drainage systems

See Algae, Ice, Fungus, Wet Surfaces & Other Stair Slip, Trip & Fall Hazards for details. Also see Exterior Stair Falls for a catalog of causes of falls on stairs that includes surface conditions and other defects.

Use of Color or Lighting to Indicate Stair & Step Changes Can Reduce Trip & Fall Injuries

Below we illustrate cases of the presence or absence of visual cues that can inform a walker that she is approaching a step. The use of color to provide a noticeable contrast between the walking surface of a passageway or floor and its steps or stairs can reduce trips and falls for walkers in either direction.

Handrail at the Metropolitan Opera is graspable where needed (C) D Friedman

Our photo (left) illustrates a handrail that is indeed "graspable" - a concern in any location, but particularly here at the Metropolitan Opera at an upper balcony where of necessity stairs are angled and steep.

You'll notice that the Met also gives visual clues (a light colored carpet strip) to help walkers discern the location of the stair tread edges.

Lighting Cues to Indicate Steps & Reduce Falls

Stair trip slip and fall hazard example - using color cues (C) Daniel Friedman

At Lincoln Center in New York City, these exterior stairs make good use of lighting to reduce the chances of stair trips and falls.

Also see Lighting over Stairs.

Lack of Color, Lighting or Other Visual Clues Increases the Risk of a Stair Fall - Examples

The tile floor shown at below left includes a 4-inch step up into a bathroom. Because the same color tiles were used on the floors at both levels as well as on the step riser, it is very difficult to see that there is a step, especially in low light. In fact the author (DF) tripped on this very step, located in a hotel in Tapalpa, Mexico. We placed a water bottle on the floor to provide a visual clue of the presence of the step riser for our photograph.

Stairs and steps can use a color change or a tile layout change to indicate a change.

In our photo left, taken in a restaurant in Rhinebeck, New York, it is still not clear from the upper walking surface whether or not we are approaching a step.

Throw Rug as Visual Cue of a Step?

A throw rug or carpet at the top of a stairway is asking for a serious stair fall even if it does provide a color change. This is not a safe way to give a visual clue about the presence of a step.

Do not place slippery items such as a rug or towel on a smooth floor at the top of steps or stairways such as the steps shown in our photo (left).

...

Frequently Asked Questions (FAQs) about details of stair tread width, depth, thickness, and tread nose construction & related building and safety codes for stairways.

Question: building code on stair tread relining

I have to skin some new construction stairs, i am going to go over the stairs with a hickory [tread] and was wondering is there a code on tread skins? - Mike

Reply: minimum vs maximum stair tread thickness: needs clarification

Mike,

Re-covering worn stair treads by installing new treads atop the original ones is a common renovation procedure.

I haven't been able to find a code citation on your question but am still looking and will report here. As you may have noted from the sketches and text above, typically building codes for stairs specify minimum stair tread thickness (1" if supported by a riser at front, or 1 1/2" thick treads if the stairs are open-construction without risers), but they do not specify a maximum allowable tread thickness. [2]. The ADA provides a comparison of stair standards among ADA and other requirements, also with no mention of tread thickness.

Watch out that your new stair skin doesn't create uneven step rise heights at the top or bottom of the stairs, nor a trip hazard at the top landing platform.

Also, let me know what you mean by "construction stairs" as OSHA has some different requirements for stairs depending on their intended use.

...

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides:
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Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
Eric Galow, Galow Homes, Lagrangeville, NY. Mr. Galow can be reached by email: ericgalow@gmail.com or by telephone: 914-474-6613. Mr. Galow specializes in residential construction including both new homes and repairs, renovations, and additions.
[3] "The Elimination of Unsafe Guardrails, a Progress Report," Elliott O. Stephenson, Building Standards, March-April 1993
[4] "Are Functional Handrails Within Our Grasp" Jake Pauls, Building Standards, January-February 1991
[5] Access Ramp building codes:
- UBC 1003.3.4.3
- BOCA 1016.3
- ADA 4.8.2
- IBC 1010.2
[6] 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
[7] The Circular Staircase, Mary Roberts Rinehart
[8] Construction Drawings and Details, Rosemary Kilmer
[9] 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. "
[10] Mobile Home Inspections common defects unique to factory built housing, inspection methods
[11] 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
[12] 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 sales@lawyersandjudges.com and also from the InspectAPedia Bookstore (Amazon.com)
[13] Slips, Trips, Missteps and Their Consequences, Gary M. Bakken, H. Harvey Cohen, Jon R. Abele, Alvin S. Hyde, Cindy A. LaRue, Lawyers and Judges Publishing; ISBN-10: 1933264012 ISBN-13: 978-1933264011
[14] 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 ] -
[14a] "Visual Interpretation Of The International Residential Code (IRC) 2006 Stair Building Code", The Stairway Manufacturers Association, [Portions of this document reproduce sections from the 2006 International Residential Code, International Code Council, Falls Church, Virginia.},
The Stairway Manufacturers Association website stairways.org provides free downloads of stairway handrailing profiles and dimensions
[15] How to Clean Moldy Wood Framing & Sheathing How to clean/seal mold from/on exposed lumber or plywood subfloor or roof sheathing indoors - some suggestions based on our field and laboratory research
[16] 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.
[17] Steps and Stairways, Cleo Baldon & Ib Melchior, Rizzoli, 1989.
[18] The Staircase, Ann Rinaldi
[19] Common Sense Stairbuilding and Handrailing, Fred T. Hodgson
[20] The Art of Staircases, Pilar Chueca
[21] Building Stairs, by pros for pros, Andy Engel
[22] A Simplified Guide to Custom Stairbuilding, George R. Christina
[23] Basic Stairbuilding, Scott Schuttner
[24] The Staircase (two volumes), John Templar, Cambridge: the MIT Press, 1992
[25] The Staircase: History and Theories, John Templar, MIT Press 1995
[26] Steps and Stairways, Cleo Baldon & Ib Melchior, Rizzoli, 1989.
[27] "The Dimensions of Stairs", J. M. Fitch et al., Scientific American, October 1974.
[28] Stair & Walkway Standards for Slipperiness or Coefficient of Friction (COF) or Static Coefficient of Friction (SCOF)
- ANSI A1264.2
- ANSI B101
- 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)
[29] 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
[30] 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)
[31] 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
[32] 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
[33] 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.
[34] Jinjin Li, Yuhong Liu, Jianbin Luo, Pengxiao Liu, and Chenhui Zhang, "Excellent Lubricating Behavior of Brasenia schreberi Mucilage" Langmuir 2012 28 (20), 7797-7802
[35] 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
[36] "Coefficients of Friction for Ice", The Physics Factbook™, Glenn Elert, Ed., retrieved 8/29/12, original source: http://hypertextbook.com/facts/2004/GennaAbleman.shtml
[37] "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.
[38] Serway Physics for Scientists and Engineers 4th edition (p. 126.)
[39] "How Slippery Is It", retrieved 8/29/12, original source http://www.icebike.org/Articles/howslippery.htm
[40] 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.
[41] 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 ]
[42] 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
[43] 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]
[44] 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

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

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Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
Decks and Porches, the JLC Guide to, Best Practices for Outdoor Spaces, Steve Bliss (Editor), The Journal of Light Construction, Williston VT, 2010 ISBN 10: 1-928580-42-4, ISBN 13: 978-1-928580-42-3, available from Amazon.com
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