InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website. Building stair stringers: Codes & strength requirements for stair support systems; how to build safe stair stringers that don't sag, squeak, collapse, or lose their treads. This article describes the construction and building code specifications for the support of residential stairways: how strong should the stringers be, and what are the load bearing requirements of stairs and their supporting stringer beams. Stair Stringer Codes & Specifications: required strength for stair supports Stair Tread Support Choices & Relation to Stair Stringer Notching • Stair treads can be placed directly on top of the horizontal surface of cutouts in the notched stair stringer. This approach is very secure provided that the stringer depth is great enough and the cutout depth shallow enough that the remaining stringer material is strong enough to carry the weight of the stairway and its users (1-? Arrow in sketch at left).

[Click to enlarge any image] Of course if the stairway is supported by securing the stringer to walls on both sides, this cutout depth weakness problem is mitigated or eliminated. More about too-deep stringer notching is in our stair stringer defects article. • Stair treads can be placed between the stringers and supported by cleats or supported by grooves routed inside the un-notched stringer.

Structural steel beams, plant decks & conveyer systems. Checkline II. Checkrail is a multiple length rail system that is simple to install and suits new or existing ladders including single. RetroGUARD™ safety panelling is retro fitted to existing and leading industrial handrails, platforms, stairs and walkways including.

If the stair treads are set into grooves routed into the stringer, in a 2x stringer the groove depth should be 1/2 the thickness of the stringer (typically 3/4') and additional support by cleats or by gluing and end-screwing through the stringer sides into the treads is good practice. • Stair treads butted against an un-grooved stringer inner face and then nailed or screwed through the stringer into the stair tread. Watch out: We do not recommend this stair tread approach as too often we find the treads break away from the stringer causing catastrophic stair tread collapse and perhaps serious injuries. If you encounter a stair built this way you should add glued & screwed cleats to support the treads. Reader Question: sagging stairway: is there a code I can check on stair stringer construction?

Rich O said: So, used improper terminology below, believe I should have used 'stringer' versus 'riser', the entire 12' stringer (wood construction) is now deflecting as if a support has failed. Thanks again, Rich My house in Westminster CO is just out of warranty and one of the staircase risers has started to visibly deflect (and squeak) when traversing the stairs. I've requested the builder take a look, in the meanwhile, is there a specific code I can refer to in order to ascertain if the stair was properly constructed? Thanks, Rich Reply: Model building code specifications for stair support stringers Yes a riser is the vertical board enclosing the space between horizontal walking surfaces, i.e.

The stringer is the support for the stairs - it functions as an angled beam and must support both the dead loads and live loads of the building stairway. Let's be clear first that a significant concern with the strength of supporting stair stringers (effectively angle beams) arise because a typical 2x12' (or rarely 2x14') stringer is in some stair designed notched to carry the stair treads on the horizontal notch face and stair risers on the vertical notch face.

My deck stair photo at left shows very deep notching in a stair stringer (as well as multiple other safety hazards and code violations). Less than 2' of lumber was left in this stair stringer 2x after the builder cut his tread notches. Notched stair stringers are widely used and are acceptable if sufficient supporting strength is provided. I prefer to avoid deflection or even collapse problems by using a solid stringer, connecting stair treads to cleats. It's also worth emphasizing that in all cases the connections are as important as the beam strength. The connections of stair stringer to the risen-to platform, of treads to stringer, and of railings and posts are critical for safe stair construction.

Those worries out of the way for a moment and assuming your question pertains to a notched stair stringer system that is sagging or deflecting, if a stair stringer is deflecting, depending on the amount, it may be damaged or may have been inadequate to begin with. For safety, investigate and determine what repair or additional support is needed. Because stringer notch depth for designs that actually notch the 2x12 or 2x14 framing lumber typically used can vary depending on stair design, codes do not specify explicit lumber dimensions.

Instead codes typically specify the strength required of the ending design. One may need to increase the number of stringers accordingly. Babylon English Human Voice Download there.

For example the IRC specifies that stairs shall be designed to withstand a live load of 40 pounds - as with a building floor. Individual stair treads shall be designed for the uniformly distributed live load or a 300–pound concentrated load acting over an area of 4 square inches, whichever produces the greater stresses. Before an inspection has been performed we don't know if the deflection of the stair stringer to which you refer is due to damage (rot for example) or a design inadequacy. But the initial focus must be on the detection of and response to any *immediate safety hazard* such as conditions that could permit a stair collapse, fall, or injury.

Here is a model building code citation for stair stringer support requirements for residential stairs using the 2003 IRC. R301.5 Live Load [Specifications for Stair Construction] Minimum required live load for Stairs 40 psf. Individual stair treads shall be designed for the uniformly distributed live load or a 300-pound concentrated load acting over an area of 4 square inches, whichever produces the greater stresses. 301.1.1 Alternative provisions [for supporting stair stringers] As an alternative to the requirements in Section R301.1 the following standards are permitted subject to the limitations of this code and the limitations therein. Where engineered design is used in conjunction with these standards the design shall comply with the International Building Code. American Forest and Paper Association (AF&PA) Wood Frame Construction Manual (WFCM). American Iron and Steel Institute (AISI), Standard for Cold-Formed Steel Framing—Prescriptive Method for One- and Two-family Dwellings (COFS/PM).

Stair Support Stringer Analysis & Strength Requirements Code & Study Citations Rich: I wanted to add that in addition to the important Frank Lam (et als) study of stair support stringers, one of the most thoughtful articles I've found on stair stringer design addresses the lack of specificity of stair stringer design in the model codes and provides some helpful engineering analysis and assumptions. See the first stair stringer code and strength requirement citation just below.

• Christopher R. Fournier, P.E., 'Wood Framed Stair Stringer Design & Construction', Structure Magazine, March 2013, p. Fournier is a structural engineer in North Conway NH. His article is available online, retrieved 4/19/14 original source: www.structuremag.org/Archives/2013-3/C-StrucDesign-Fournier-March13.pdf • Aghayere, Abi, and Jason Vigil. 'Introduction: Wood Properties, Species, and Grades.'

Structural Wood Design: A Practice-Oriented Approach Using the ASD Method: 1-24. • Aghayere, Abi, and Jason Vigil. Structural Wood Design: A Practice-Oriented Approach Using the ASD Method (2008): i-xii. [See Chapter 27, 'Combined Dead and Live Loads on Stair Stringers'] • Berge, Greg Vanden. Simplified Stair Building.

Greg Vanden Berge, 2012. • De Tennis, Danielle. 'Strength Testing and Analysis of a Stair Header Connection.' PhD diss., Milwaukee School of Engineering, 2010.

Super Mario War Download Softonic Downloader on this page. • Higgins, Christopher. 'Prefabricated steel stair performance under combined seismic and gravity loads.' Journal of structural engineering 135, no. 2 (2009): 122-129. • Kourakis, Ioannis, and Shawn Li. 'Design of a Glass Stair.'

In Structures Congress 2010, pp. • Lam, Frank, George Lee, Huijun Yan, Jianzhong Gu, and Ata A. 'Structural performance of wood-based stair stringers.'

Forest products journal 54, no. The preceding citations focus on the supporting stringer used in stair construction and on angled beams and strength requirements. For a complete list of stair building codes see the two live links immediately below. • - Model & actual building codes for stairs, railings, guardrails, landings, risers, treads, and steps • - Specifications for Stairs, railings, guardrails, landings, treads, & steps based on model & actual building codes. Continue reading at for exact procedures for laying out and cutting a stair stringer. Or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see Suggested citation for this web page at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice. INDEX to RELATED ARTICLES: Or use the found below to Ask a Question or Search InspectApedia. • [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], Mary Roberts Rinehart • [8], Rosemary Kilmer • [9], Lawyers & Judges Publishing, (June 2002), ISBN-10: ISBN-13: 9438 '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] 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 NI • [12], Second Edition, Gary M. Harvey Cohen,A. 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 (Amazon.com) • [13], Gary M. Harvey Cohen, Jon R.

Abele, Alvin S. Hyde, Cindy A. LaRue, Lawyers and Judges Publishing; ISBN-10: ISBN-13: 9011 • [14] The Stairway Manufacturers' Association, (877) 500-5759, provides a pictorial guide to the stair and railing portion of the International Residential Code. • 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email:.

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