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Cable rail codes/inspector problems!

J

joeturner38

Member
Joined
Feb 9, 2011
Messages
2
Problems with inspector with cable railing that has a post every 4' o.c. with an intermediate every 2'. Five line cable 1/8"ga. @ 3-1/8" apart. Railing is 2 feet off the ground sitting on top of a wall. Cable is at 300lb. tension as per manufacture specifications. City inspector has repeatedly rejected the rail and is referring me to code 1607.7.1.2.

Inspector is spreading the cable apart with both hands and is stating that the cable has a spacing of more than 4" when using his method of inspection. We feel that this is not a proper way of inspecting. Has anyone ever had an experience like this?
 
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welcome! The code isn't specific about how to inspect, but as all guardrails (including the cable ones) are required to resist 250 # (I believe exerted laterally), there is nothing to prevent the inspector from trying to pull the cables apart. Gotta think like a kid.

Having said that, everytime I've seen this type of guard, the turnbuckles tighten to the point that pulling the cables apart is tough.
 
Joe,

Welcome to the forum...

Here in lies my questions for the inspector.

1. How much force are his hands putting on the cables to spread them a part? He could very easily be applying more than 50lbs or more force if he has strong fingers.

2. PEACH 2?'s

(1) were are you pulling the 250 # figure from?

(2) 1607.7.1.2 is specific that 50lbs be applied horizontally on an area equal to 1 sgft.

1607.7.1.2 Components. Intermediate rails (all those except the handrail), balusters and panel fillers shall be designed to withstand a horizontally applied normal load of 50 pounds (0.22 kN) on an area equal to 1 square foot (0.0929 m2), including openings and space between rails. Reactions due to this loading are not required to be superimposed with those of Section 1607.7.1 or 1607.7.1.1.
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So how the inspector can pull the cables a apart vertically with fingers per this section is very unclear to me. If using his fingers only for force then one must take that area (lets say 1 square inch per finger exclude the thumbs that is 8 fingers or 8 square inches.

Next get the dif from 1 square foot which is 144 square inches 144 / 8 = 18

Take the 18 and divide that in to the 50 lbs (50 / 18 = 2.78 lbs)

Thus if it takes more than 2.78 lbs to pull the cables a part they pass. Even if we add a safety factor of (4 like for glass) that is only 11.12 lbs I am pretty sure the inspector is pulling more than 11+ lbs.

2. To check this I would personally take a fish type scale hook it to one cable pull downward with 12.5lbs of pressure if less than 4" in mid span, what is the deal.

The fish scale test is not certified, but here in lies the question for all.

since the inspector is quoting 1607.7.1.2

Is this not a load test? And if this is a load test are the

1. inspectors qualified to perform load tests?

2. allowed by code to preform load tests?

3. have the proper equipment in the field to very compliance

4. if presented with a certified engineers report stating loads comply how does his finger test apply

I have more but these are my questions first off for all on the forum.

I will end with I am not sure of Joe's construction, I would post pictures if it was me and have construction verified by engineer. But from the post 300lb tension, 2ft between verticals and 3.125 spacing on 1/8" cables should have no problem surpassing code compliance and should sing like a guitar.

Tom

3.
 
The correct test would be to take a young child's head and push it against the cables with a force of 50 lbs. One may substitute a 4" sphere for the child's head if said head is not available or willing. If the head or the sphere pops thru the cables, there is a failure.
 
A horizontally applied "normal" load.

What is "normal"?

I think that pulling the cables apart (up and down away from each other) is neither normal, nor is it horizontal.
 
Yankee nailed it. I would strongly recommend the sphere... when the sphere pops through, you can let it drop. If the head pops through...well, that's a whole nuther problem.
 
The 50 pounds is not applied to a 4 inch sphere. The 50 pounds is applied over a one square foot area. This would hit at least a couple of cables. With this 50 pounds applied, the cables cannot deflect to permit passage of the four inch sphere.
 
Yankee said:
The correct test would be to take a young child's head and push it against the cables with a force of 50 lbs. One may substitute a 4" sphere for the child's head if said head is not available or willing. If the head or the sphere pops thru the cables, there is a failure.
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Hi Yankee,The 50 Lbs is per square foot so A=3.1416*2^ A=12.56 Sq Inches. If 144 sq in must resist 50 Lbs, 12.56 sq in must resist 4.36 Lbs. By your standard, which I believe is invalid since the 50 Lbs is lateral force resisted not spreading force between balusters or cables. I've built plenty of railings with cedar 2X2 balusters with 3.5" space between balusters and every one would fail if a 4" sphere were pushed with 50 Lbs of force.In any case some months ago, I called the local plans examiner and he ginned up the same standard you proposed ( 50 Lbs pressure on 4" sphere ). I decided to quit arguing and take it up with the field inspector who approved and complimented my railings.Turned out to be a non problem.BillView attachment 409

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Yankee & Darren,

By what wording in the code is Yankee's statement right?

The correct test would be to take a young child's head and push it against the cables with a force of 50 lbs. One may substitute a 4" sphere for the child's head if said head is not available or willing. If the head or the sphere pops thru the cables, there is a failure.
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Glenn,

Normal is without a safety factor added and steady force, not pulsing like shove - ease off - shove, at least that is what I have been informed by engineers at many code hearings and project meetings, but I have been wrong before.

As to applying a 50lb load on a 4" sphere that is way off and does not even match the ASTM standards for infill test spreading. YES people there is a decades old, ASTM standard just for this type of testing that the codes have never adopted.

ASTM E935, I have posted this many times on the (what do you call it site) the thing of the thing before.

Applying a 50lb load to a 4" sphere is in NO CODE EVER PUBLISHED by any of the model codes that I have ever seen, it is a MYTH, ask the ICC for an interp and you will get it, NO LOAD on the 4" sphere it is in chapter 10 ( configurations and measurements) NOT chapter 16 loads.........:beatdhrs

EVEN if you were go with the spreading, passing a 4" sphere does not equate to failure under the ASTM standard, head getting stuck in guard does not equate to failure, they got stuck it is like the fly trap.

It's all about the full body passing.

Why do we allow a 6" sphere on the tread and riser area? surely 4" passes.....

If you require 50lb's on a 4" sphere in your AHJ you better have failed pretty much every wood deck balusters installation nailed to the 2x4 cross rails, then fail all the plastic balusters, and the foam based products and then even a good bit of 1/2" square hollow steel balusters that are not spaced within 3.5".

Because pretty much under that stated requirement, if you requested an engineer to certify it, or you tested it with a sphere, force gauge and meter you would see, N-G.

This is almost as bad as the wood people that believe that posts are required by code to make a guard, another myth.
 
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tbz...you nailed it!

I doubt the inspector will see it that way though. Some of these guys are unteachable and have it a certain way in their head on how to inspect. Try to approach it in a scientific way...good luck. They might have to go over his head. Not to sterotype, but I've seen this before.
 
I haven't checked this thread out in a awhile, but I do agree that the 50 lbs is to be over a square foot area. My previous answer was somewhat facetious, but the basic idea still stands . . . does a head size pressure spread the cable rails or not (if the head goes thru, the rest can too, kids have a larger percent of head/body ratio than adults). I agree that spreading apart with two hands is not the way to test the cable railing.
 
The baluster spacing and applied 50# laod are two distinct and different requirements. You don't mix and match them to fit the need. Although it does seem to make sense to use the 4-inch/50 lb. applied load, there is nothing in the code to substantiate that method.
 
High Desert said:
The baluster spacing and applied 50# laod are two distinct and different requirements. You don't mix and match them to fit the need. Although it does seem to make sense to use the 4-inch/50 lb. applied load, there is nothing in the code to substantiate that method.
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Yes, they are for distinctly different reasons but nothing is written "distinctly" for cable guards or any other guard that might have moving parts that change the 4" minimum spacing. SO one has to interpolate between two separate code intents.
 
Get a piece of 12" x 12" plywood, press it against the cables with a 50 lb. force and see what happens. That's what the code says the cables need to support, not whether a 4-inch sphere can fit through with a 50 lb. force. I disagree that you have to interpolate.
 
High Desert said:
Get a piece of 12" x 12" plywood, press it against the cables with a 50 lb. force and see what happens. That's what the code says the cables need to support, not whether a 4-inch sphere can fit through with a 50 lb. force. I disagree that you have to interpolate.
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How about we take the situation to the extreme, and use rubber bands as cables. It could be that your 1' square plywood at 50lbs/per passes this test as well, but only a slight force is capable of separating the rubber band cables widely. Would you say that the rubber band cables meet the code and also meet the intent of the code?
 
Yankee said:
How about we take the situation to the extreme, and use rubber bands as cables. It could be that your 1' square plywood at 50lbs/per passes this test as well, but only a slight force is capable of separating the rubber band cables widely. Would you say that the rubber band cables meet the code and also meet the intent of the code?
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Part of me wants to say, if you don't like how the code is written, then change the literal words of the code, but let's not make up an inference from the code.

The other part of me wants to respond to your challenge - - in the end, we're all about safety. If I recall correctly - oldtimers, please help me out here - the INTENT of the change from 6" baluster spacing down to 4" came not because the kid might fall through, but rather that the kid might get his head stuck. I recall some studies where they were concerned about stair balusters: a kid takes a tumble, his head pokes through the balusters, gets stuck, and his neck is injured as his body continues the tumble.

In this scenario, the rubber bands flex around the head as it is pushed in, then flex again as it is pulled out. Intent is met???
 
Glennman CBO said:
A horizontally applied "normal" load.What is "normal"?

I think that pulling the cables apart (up and down away from each other) is neither normal, nor is it horizontal.
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From the physics and mechanics classes I have taken, "normal", when referring to forces, means acting perpendicular to the surface. My thinking is that it would cover the cases of, say, triangle shaped or slanted infill pieces.

I would agree with Glennman that pulling them up and down should not be used to verify this requirement.
 
I have passed cable guards in the past and expect to in the future. But I know if I come across some cable guards that act like rubber bands, I believe it is within the scope of my authority to not pass the construction. We are tasked with approving equivalences all the time and with that, we also must disapprove what we believe is nonequivalent to the code intent.
 
Yankee, I agree with you to a point, but you can't create your own standards for something to NOT pass your inspection of something you may not like , but does meet the code. There's fine line that separates the intent vs. your feelings on the issue. When your close to that line is when it becomes difficult to make a determination.
 
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Yikes said:
Part of me wants to say, if you don't like how the code is written, then change the literal words of the code, but let's not make up an inference from the code.The other part of me wants to respond to your challenge - - in the end, we're all about safety. If I recall correctly - oldtimers, please help me out here - the INTENT of the change from 6" baluster spacing down to 4" came not because the kid might fall through, but rather that the kid might get his head stuck. I recall some studies where they were concerned about stair balusters: a kid takes a tumble, his head pokes through the balusters, gets stuck, and his neck is injured as his body continues the tumble.

In this scenario, the rubber bands flex around the head as it is pushed in, then flex again as it is pulled out. Intent is met???
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1991 UBC had the spacing as 6" if I remember correctly. Not real sure as I sometimes suffer from CRS. :lol:

Sue, where the west still lives....................
 
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