What Is “The Ladder Effect”?

The 2000 International Residential Code (IRC) states that guardrails . . . shall not be constructed with horizontal members or other ornamental pattern that results in a ladder effect. It has never been in the International Building Code (IBC).

This was removed in the 2001 code cycle and was published in the 2001 IRC supplement. It has remained that way and is not in any subsequent publications of the IRC. It has never been in the IBC.

However, the confusion over this issue remained and became the subject of multiple hearings of the International Code Council’s (ICC) Code Technology Committee.

The output of those hearings was a report from the National Association of Home Builders (NAHB) Research Center in October, 2007

The report is titled Review of Fall Safety of Children Between the Ages of 18 Months and 4 Years in Relations to Guards and Climbing in the Build Environment. Funded by the National Ornamental and Miscellaneous Metals Association (NOMMA) Education Foundation , the study was commissioned as a means of clarifying conflicting interpretations of guard climbing studies and injury data.

Over 40 peer-reviewed studies were reviewed for the report covering the areas of children’s physical development and their interaction with the build environment. The review of the studies resulted in this set of conclusions:

  • “The human child is built to climb and loves to do so!” (Readdick and Park, 1998).
  • Climbing is involved in the child’s physical, psychological and social development.
  • Climbing skills are often taught and encouraged by parents, especially with boys
  • Climbing is a part of physical education at school.
  • No evidence of a gender difference in either climbing skill or climbing speed in young children.
  • Difficult barrier designs merely present a greater challenge to the determined child.
  • Studies also generally agree that it is probably impossible and most likely undesirable to render any environment completely “safe” from children’s climbing

The NAHB Research Center’s review went on to analyze Consumer Product Safety Commission (CPSC) data collected by the National Electronic Injury Surveillance System (NEISS). Previous analysis of this data had been unscientific and inconclusive. Following a thorough, scientific analysis, the review of NEISS data resulted in the following conclusions:

  • The results indicate that falls from Porches, Balconies, Open-Side Floors, Floor Openings Handrails, Railings, Banisters among young children aged 18 months to 4 years account for an estimated 0.032 percent of injuries in that population.
  • The incident rate is approximately 2.5 per 100,000 children between 18 months and 4 years of age
  • There is much uncertainty in the data to ascribe causality or the physical situation that lead to reported injuries.

The CTC made a point of thanking NOMMA for having kept its promise and providing a well-documented report which they expect to use for other issues such as window falls and pool barriers.

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