# History and meaning of the 4 inch rule for guards fences etc...



## Hesterd (Mar 18, 2014)

Hello all for one.

I have a curious question. The rule/intent of 4 inch for balusters, guards and like. I always thought was based on head entrapment. I know the rules started off as preventing through fall when spacing was larger. Curious if someone has the good history on this.


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## mark handler (Mar 18, 2014)

Hesterd said:
			
		

> Hello all for one. I have a curious question. The rule/intent of 4 inch for balusters, guards and like. I always thought was based on head entrapment. I know the rules started off as preventing through fall when spacing was larger. Curious if someone has the good history on this.


You are correct.  The intent was to prevent children from going through.


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## ICE (Mar 18, 2014)

A child's head will fit through any gap that is greater than the size of it's head.  At one point it is the size of a walnut.  Later it's an orange and finally a melon like what Brent hauls around.  The four inch dimension is only effective for a segment of a child's growth cycle if it is to prevent entrapment of a head.  Why not 3" for a different segment.  So I don't think it has anything to do with baby heads.


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## Francis Vineyard (Mar 18, 2014)

From the BOCA magazine Nov. - Dec. 1988; The Silent and Inviting Trap by Elliott O. Stephenson


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## JBI (Mar 18, 2014)

_"At one point it is the size of a walnut. Later it's an orange..."_

ICE, those would be in the womb...

D'OH!:banghd


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## mjesse (Mar 18, 2014)

JBI said:
			
		

> those would be in the womb...


Or, in the circus...
	

		
			
		

		
	

View attachment 1026


View attachment 1026


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## MASSDRIVER (Mar 18, 2014)

ICE said:
			
		

> A child's head will fit through any gap that is greater than the size of it's head.  At one point it is the size of a walnut.  Later it's an orange and finally a melon like what Brent hauls around.  The four inch dimension is only effective for a segment of a child's growth cycle if it is to prevent entrapment of a head.  Why not 3" for a different segment.  So I don't think it has anything to do with baby heads.


I get stuck in street manholes.  Too much brains.

Brent


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## Frank (Mar 18, 2014)

A 1-1\2- 2 year old can walk through 6 inch spaced pickets.  Just before the hearing we were at my brothers on his new neck and I was sitting on the top of the steps to keep my toddler son from falling down the steps.  He turned sideways and stepped right between the 5-1/2 inch spaced pickets and was standing on a 6 inch ledge 5 ft off the ground when I grabbed him.  I questioned my brother if his builder had spaced the pickets correctly and they measured right at 5-1/2 inches spaced by the 2x6 with a handle method.  I related this story at the BOCA code change hearing supporting this change.  There were arguments for the 2-3/8 inch crib rail spacing to prevent head entrapment but it was argued that the 4 inch spacing was adequate to keep in toddlers that could walk.  The testamony at the BOCA hearings also mentioned a couple cases where kids had run off from parents in malls and taken a quick trip to the floor below.  The two story mall here, on the "advice" of their insurer, put up temporary plywood on the inside of their rails untill the new glass railing system could be installed.  This was before the 4 inch standard was formally enforced here.


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## ICE (Mar 19, 2014)

MASSDRIVER said:
			
		

> I get stuck in street manholes.  Too much brains. Brent


That happens to fatboy ..... but it's not brains.


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## High Desert (Mar 19, 2014)

I remember in the late 70's the spacing was 9 inches. Then somewhere along the line it became 6 inches, Until we arrived at less than 4 inches. My only guess is that baby's heads are getting smaller.


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## MASSDRIVER (Mar 19, 2014)

It's Darwin at its finest. In three years they will squeeze through keyholes like mice.

We aren't helping them here. They just adapt.

Brent.


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## fatboy (Mar 19, 2014)

"That happens to fatboy ..... but it's not brains."

Well...........we won't go there.

I thought the spacing went from 8" to 6" to 4", (then to 4 3/8" on stair runs), will do some research tomorrow.


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## JBI (Mar 19, 2014)

If memory serves me correctly... NFPA 101 used to allow either less than 6" (to avoid head fitting through) *or* greater than 9" (to allow head to come back out easily). The issue was clarified when children fell through the wider spacings on elevated decks/balconies. At that point is became < 4", eventually the stair folks got the 4 3/8" on stair runs due to stair geometry and aesthetics.

But I could be mistaken...


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## Gregg Harris (Mar 19, 2014)

spacing
	

		
			
		

		
	

View attachment 2307

	

		
			
		

		
	
Try this

View attachment 1027


Sbizhub_c6512101710260.pdf

Sbizhub_c6512101710260.pdf


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## fatboy (Mar 19, 2014)

Thanks Gregg, nice article.


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## Rick18071 (Mar 19, 2014)

Is it 4 3/8" on stairs because only biger kids get to use the stairs?


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## Francis Vineyard (Mar 19, 2014)

Rick18071 said:
			
		

> Is it 4 3/8" on stairs because only biger kids get to use the stairs?


Commentary; "Exception 6 is to allow a stairway within a residence that chooses to use the 7-inch rise/11-inch run (178 mm rise/279 mm run) stair configuration to have two spindles per stair tread instead of three spindles. Where the 73/4-inch rise/10-inch run (197 mm rise/254 mm run) configuration (see :Next('./icod_ibc_2009f2cc_10_par096.htm')'>Section 1009.4.2, Exception 5) is utilized, the two spindles would meet the 4-inch (102 mm) maximum provision."


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## steveray (Mar 19, 2014)

If they are smart enough to use the stairs they won't get stuck...Makes me look like a wicked jerk when I call a guy on his 4-1/16" balluster spacing on his deck...


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## Francis Vineyard (Mar 19, 2014)

Initially the code change proposal submitted by Elliott Stephenson to reduce the opening between 34 and 42 inches to 4.375 inches from 8 inches was disapproved for climbability; but made it (approved) into code without explanation.

The new height exception for R-3 and within R-2 not more than 3 stories uses injury statistics for potential risk with different heights for example reducing the gap at the bottom to 2 inches where 6 ft. or more above the surface below to prevent objects from "rolling" underneath and hitting a person below.

ICC Code Technology Committee Climbable Guards


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## fatboy (Mar 19, 2014)

I was at the hearings when the 4 3/8" on the stairs was approved. Part was cosmetic, but it was also argued successfully that toddlers were not spending that much time on stairs vs. flat walking surfaces.


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## Gregg Harris (Mar 19, 2014)

Francis Vineyard said:
			
		

> Initially the code change proposal submitted by Elliott Stephenson to reduce the opening between 34 and 42 inches to 4.375 inches from 8 inches was disapproved for climbability; but made it (approved) into code without explanation. The new height exception for R-3 and within R-2 not more than 3 stories uses injury statistics for potential risk with different heights for example reducing the gap at the bottom to 2 inches where 6 ft. or more above the surface below to prevent objects from "rolling" underneath and hitting a person below.
> 
> ICC Code Technology Committee Climbable Guards


Funny how that happens.


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## JBI (Mar 19, 2014)

The Code limits opening size, not balluter spacing... :roll:


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## steveray (Mar 19, 2014)

JBI said:
			
		

> The Code limits opening size, not balluter spacing... :roll:


Correct!....I've never seen a balluter.....


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## JBI (Mar 19, 2014)

Not a sawhorse, so can't edit... 'balluSter spacing' is not regulated by the Code.

"If they are smart enough to use the stairs they won't get stuck...Makes me look like a wicked jerk when I call a guy on his 4-1/16" balluster spacing on his deck..."

Mine was a spelling error, yours was a poor choice of words or an attempt to regulate something the Code does not address... ops

"


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## tbz (Mar 25, 2014)

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 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 99% majority of the children can't pass their bodies or heads through 4" wide vertical spacing.  The 4" is based on 2 vertical or angled bars in parallel, it's not really a sphere thing, it's an area thing.  We can all agree that there is no issue with a 6" round opening in a guard with a child going through, we allow this as an exception, but a opening 34" tall set 6" apart is a problem.

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


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## skipharper (Apr 22, 2014)

The way I recall it going from 6" to 4" is when Eric Claptons kid fell to his death from a Manhatten high rise.


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