NC IBC 2018 - Proposed Code Modification 1015.4

[tbz]

Hello looking for comments on the proposed wording that is currently in front of the NC Building Code Council for the building code which has a meeting next week. The 2" sphere requirement has been in their code since 2009, but of concern to me is the bold under lined area trying to pull loads in to chapter 10 were they dont belong, not to mention the wrong wording for the load requirement.

Please let me know what you think and if you are from NC, what can you tell me about this since they don't seem to publish and reason statements on the proposed modification from model code.


1015.4 Opening limitations. Required guards shall not have openings that allow passage of a sphere 4 inches (102 mm) in diameter from the walking surface to the required guard height. The sphere shall not pass through the opening with a minimum of 50 psf applied horizontally to the sphere from the direction of the walking surface that is being protected. A bottom rail or curb shall be provided that will reject the passage of a 2-inch-diameter (51mm) sphere.

 

[RLGA]

Some infill materials used for guards may not allow passage of a sphere by just placing the sphere against the infill members, but it may be able to pass through if sufficient force is applied. For example, tensioned cable systems may have a less than 2-inch spacing, but because they can flex, a 2-inch sphere can be easily pushed through.

 

[Francis Vineyard]

Apparently NC is taking it upon themselves to do what the ICC CTC will not approve because of increased cost of construction. However it is a required provision in Table 303.2 of their ICC 300 - 2012 Standard for Bleachers, Folding and Telescopic Seating, and Grandstands!

S72–07/08
1607.7.1.2; IRC R312.2
Proponent: Bruce Dodge, Building Official, City of Grand Haven, MI, representing himself
Revise as follows:

R312.2 Guard opening limitations. Required guards on open sides of stairways, raised floor areas, balconies and porches shall have intermediate rails, balusters, cables or ornamental closures which do not allow passage of a sphere 4 inches (102 mm) or more in diameter except when a force greater than 50 pounds (0.22 kN) is applied to the sphere in any direction.

Exceptions:

1. The triangular openings formed by the riser, tread and bottom rail of a guard at the open side of a stairway are permitted to be of such a size that a sphere 6 inches (152 mm) cannot pass through.

2. Openings for required guards on the sides of stair treads shall not allow a sphere 4 3/8 inches (107 mm) to pass through

Reason: With guard rails being made of plastic or cables which can be very strong in one direction and weak in the other I have found some guard rails that can be spread with little effort allowing a four inch sphere to go through with little or no effort. Section 1607.7.1.2 only require the 12 inch square horizontal test showing that the components will withstand the side pressure of 50 pounds. I spoke to ICC about this issue and found that when ESS approves a guardrail system the guardrails are tested to an ASTM Standard but it does not include a requirement to test for separation of the components.

What good is a guardrail if children can squeezes through? Therefore, I’m proposing a change to require that the balusters / components of the guardrail be test to show that it will take a minimum of 50 pound pressure to spread them apart to allow a 4 inch sphere to pass through. An inspector, manufacture, or contractor can do a test very easily by getting a 4-inch sphere and a fish scale and pulling the 4 inch sphere through the railing when an inspector thinks that it will not meet the 50 pound test.

I have inspected guardrails where a 4-inch sphere will come through the balusters with less than 10 pounds of pressure. Next time you see a plastic guardrail try putting your knee through the balusters and see how much pressure it takes. Some I have tried are very strong but others will allow it with very little pressure.

Cost Impact: The code change proposal may increase the cost of construction.

http://iccsafe.org/cs/CTC/Documents/guards/CodeChanges/CTC_guards_related_code_changes.pdf

 

[sergoodo]

but of concern to me is the bold under lined area trying to pull loads in to chapter 10 were they dont belong, not to mention the wrong wording for the load requirement.

Yes, molestation of the divine organization is very annoying. My comment is if a 4" sphere can pass thru it does not comply, if I push that sphere thru with 200# of force...does not comply.

I would ask exactly how to test this force requirement? Lab?. Sphere test failed...no it didn't, show me the test data.

 

[tbz]

Thank you everyone for the notes,

Francis, for years I was a big supporter of the ASTM E935 infill spread cone test. The building codes never adopted it nor could anyone get the engineers to even look at it.

It was removed from the standard in 2013 after being in it for decades when the standard was aligned to follow what the IBC and IRC had for text.

My issue with the current wording is more that it is totally out of context. Take "sergoodo" reply above, it is well documented that the 4" sphere in chapter 10 is a measurement not a load test, yet inspectors want to apply a load for the shall not pass through.

The proper testing method for the 4" sphere measurement is to apply the infill component load test in 1607.7.1.3 and then check if the sphere will pass through. In other words infill under the test load and if the infill spread enough to allow the sphere to pass then it fails. Not load up the sphere.

But how does one test a load when the majority of the inspectors don't have the correct equipment nor the training or certification to preform the test load pass or fail test to begin with.

So you have this wording in the incorrect section, you don't note if the load is a design or performance load, and then what is the approved test method, ie equipment to do it with. Then lets look at the wording on it's self. " with a minimum of 50 psf applied" the first issue I see glaring is the word minimum, does this mean it also has to hold higher loads?, then lets look at the 50 psf, the way I see this written is since the 4" sphere is only 1/9th of a sqft, your load is only 5.55 lbs to the 4" sphere.

I could go on and on, but I guess my question should be to you all, if this exact wording was in your adopted code how would you go about enforcing it?

Thanks again for the responses in advance - Tom

 

[steveray]

Same way I do a guardrail or 5lb/15lb door test....Guess....Maybe I will start requiring special inspections for guards....

 

[Francis Vineyard]

My guess would be a solid 4" sphere with a calibrated fish scale of 1/2 lb. or in. lb. increments.

 

[steveray]

Are kids really plowing through guards these days? Are they also changing it for the stair areas (4-3/8")?

 

[RLGA]

tbz:

Where the load requirements in Chapter 16 are for the structural support of the guardrail, the load for the sphere test is only to show that a person (most likely a child) could probably not squeeze their head through the guardrail elements -- it has nothing to do with the guardrail's ability to withstand a structural load. As for wording, I don't see a problem with it except that the units used is incorrect. They should have used pounds similar to that used in Section 1010.1.3 (2015 IBC) for door opening force.