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This document provides building code specifications, sketches, photographs, and examples of the proper step height or stair riser dimensions and other stair riser requirements for indoor or outdoor stairways. Photo at page top shows a wood exterior stair during construction by the author D. Friedman and associate Art Cady. Because of the tricky uneven ground and the difficulty of accurately measuring rise off of a rough slope, the builders set the downhill stringer in place first, and determined remaining stair construction measurements based on the location of that stringer. Railings and balusters are incomplete in the photo.

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. Also see Building Safety Hazards Guide. Here we include references to key documents on building codes and stair and railing safety.

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Stair Stringer Defects

The stair stringer is the diagonal supporting structure that carries the weight of the stair assembly as well as people using the stairs. You can see a stair stringer along the upper-edge of the set of stairs lying on their edge in our photo at above-right, after the stairs fell from the stair opening (our photo at above left) during a building renovation project. The stair stringer is secured to the structure at stair top, stair bottom, stair sides, depending on where there are building surfaces present.

Some common stair stringer defects we've found include:

• Stair stringer poorly secured to the top landing of exterior porches and decks
• Stringer loose, rotted, damaged, bowed, not secured to the building side wall where it should be, indoors or out
• Stringer improperly cut, deep notching, under-strength (see photo at Stair Riser Specifications & Defects)

Rotted stair treads or stringers: watch for rot in wooden stairs, especially at exterior entrances and decks. Where the stair stringer is mounted against a building wall water is often trapped, leading to hidden rot and sudden collapse.

Our photo shows rotting basement stair treads; from the stair top we could see that the entire stairway was twisting and in danger of sudden collapse. The sketch, courtesy Carson Dunlop, predicts stair rot exactly where it's found in our photograph.

This exterior stair ascending to a deck used a stringer pair that was so bouncy the builder decided to retrofit additional support at mid-span of the stair stringer. A post secured to a pier and to the stringer side on each side of the stairway may have been a stronger solution. We like to set posts at mid span as well as at the bottom landing quite securely to prevent unsettling movement when descending or ascending a tall exterior wood-framed stair such as this one. Notice also the obsolete side railings which are not child-safe.

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

STAIRS, RAILINGS, LANDINGS, RAMPS
  Attic stairs
  Balusters & Railing Enclosures
  Basement Stairs & Walkout Covers
  Books on Stair Construction
  Checklist for Stair Inspections
  Codes for Stairs
  Exterior stairs
  Fire Stopping for Stairways
  Guardrails on Balconies & Landings
  Lighting over Stairs
  Railings on Stairways
  Ramps, access
  Stair dimensions: width height &c
  Stairway headroom
  Stairway landings
  Step riser dimensions
  Step stringer defects
  Step tread dimensions
  Stair tread nose dimensions
  Winder stairs

• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

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

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• "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
• 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)
• The Stairway Manufacturers' Association, (877) 500-5759, provides a pictorial guide to the stair and railing portion of the International Residential Code.
• The following stair books and other books on stair history, design, and architecture can be purchased at our Amazon-Supported InspectAPedia Bookstore
• Steps and Stairways, Cleo Baldon & Ib Melchior, Rizzoli, 1989.
• The Staircase: History and Theories, John Templar, MIT Press 1995
• The Staircase (two volumes), John Templar, Cambridge: the MIT Press, 1992.
• "The Dimensions of Stairs", J. M. Fitch et al., Scientific American, October 1974.
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