tbz
Silver Member
I guess I have to chime in here since I wrote the code change for the 4-3/8" baluster spacing for both IRC stairs and reducing the 8" sphere between 34 & 42 to 4-3/8"
The reduction of the 8" sphere along the upper area of a guard was done because of cases reviewed during the CTC study of climbable guards, there were a small amount of cases found where children's bodies had passed through the 8" opening but the heads did not and thus they were found in distress with feet not touching the floors. Thus the group decision was made during the CTC meetings to reduce the 8" sphere to 4-3/8" which was currently the largest long parallel span the group could agree on. The 4-3/8" on the upper opening was a CTC, Elliot had wanted 4" and less than that.
If you want a complete history of the changes and follow it in more depth you can visit the ICC-CTC website, under climbable guards and review all the documentation from start to finish every the compilation of the 4" sphere history through the code organizations. It's all there to read.
Tom
- The IRC has a stair geometry of 7-3/4" on 10" in the model code
- With the 10" tread and and (2) 3/4" or larger balusters you can set only (2) balusters per tread.
- I also showed that the size of Kids that could negotiate stair flights, had larger body and head configurations than that of a child rolling on a landing towards balusters.
- I also presented information that explained that with a 6" sphere requirement that the opening on the lower portion was open to a fall through than the 4-3/8".
- The 99% was equally as fine with 4-3/8" as 4" when you review sizing information.
- I also stated that though I was fine with a 4-3/8" sphere for all, that I only request it here on stair flights and would speak against any movement to increase the 4" sphere to 4-3/8" throughout the codes and have.
The reduction of the 8" sphere along the upper area of a guard was done because of cases reviewed during the CTC study of climbable guards, there were a small amount of cases found where children's bodies had passed through the 8" opening but the heads did not and thus they were found in distress with feet not touching the floors. Thus the group decision was made during the CTC meetings to reduce the 8" sphere to 4-3/8" which was currently the largest long parallel span the group could agree on. The 4-3/8" on the upper opening was a CTC, Elliot had wanted 4" and less than that.
If you want a complete history of the changes and follow it in more depth you can visit the ICC-CTC website, under climbable guards and review all the documentation from start to finish every the compilation of the 4" sphere history through the code organizations. It's all there to read.
Tom
