Deck Rail Cable Opinions Please

Came across this today and would appreciate some opinions.

The top portion has 2 cables running horizontally to meet the 4" gap requirment.

Near the center of the run it’s easy to spread the cables to beyond 4"

I would like to hear some opinions on this Rail #1 construction.

Deck Rail.jpg

In some areas they do not allow the horizontal details as it lends itself to the ladder affect. Check with your local ahj.

Bruce, Thanks for chiming in. I didn’t consider that a problem as it was on the top 10" or so.

How about this rail example #2 ?

Rail 1146 .JPG

Ya but I see all these custom decks with the pretty cable railings and wonder how they get away with it.

Yours may still be a ahj issue, I have known some that would look at that and say the railing is not tall enough because they will not take the top section into account.

I still get this from my remodeling days, lots of good info.

an Electric fence unit is all that’s missing for rail #1.

Perhaps that answers the original inquiry. I was thinking the same thing regarding the spread you mentioned which was easily greater than 4". Assuming it is okay with the local AHJ, I don’t think a kid can fall through it and they definitely won’t get their head stuck.

If the ladder affect isn’t a concern due to it’s height then the spread really wouldn’t be a concern either. The ones I have come across with cables are all under much greater tension and the runs between posts are shorter. Wouldn’t an extra post be required anyway?

I would mention exactly that in the report.

Cable flexibility is an important consideration in designing a cable railing. The old UBC (Uniform Building Code) and newer ICC (IBC and IRC) codes state that a 4” sphere shall not pass through any portion of a barrier on a guardrail rail. In a horizontal or vertical cable rail, the cables, once tensioned must be rigid enough to prevent deflecting enough for a 4 inch ball to pass. Factors influencing this rigidity are: the tension of the cable, intermediate posts (or cable spacers)spacing, the diameter of the cable, top rail cap material and the cable to cable spacing.
Cable Tension: An incredible amount of tension is generated on the end posts when ten or more cables, each tensioned at 200-400 Ibs. over a height of 36" to 42” exists. Many people do not understand the amount of the tension applied to the posts. Poorly designed end posts will result in a railing where the cables cannot be properly tensioned without an unacceptable amount of cable deflection. End posts to which the tensioning hardware attaches must be constructed so that they will not deflect perceptively as the cables are tensioned.
Post Spacing: Intermediate posts are posts which provide mounting for the top rail and have a vertical row of holes to support the cable as it passes through them. Since the post to post spacing is a primary driver of cable rigidity, the post to post spacing is very important (typically between 36" and 42").
Cable Diameter: The next variable is the diameter of the cable. Cables can be 1/8, 3/16 or 1/4 inch diameter. The larger the diameter, the more rigid (and costly) the cable.
Top rail: Top rail material must be strong as it is being compressed by the combined cable forces. Common top cap materials are the stronger species of wood or metal. Composite lumber is not suitable.
Cable to cable spacing: Spacing of the cables vertically is critical to minimize deflection of the cables. Most manufacturers recommended maximum vertical spacing of 3-inch free opening between cables when they are installed.
All of the above factors work together to minimize the deflection of the cable to prevent a 4” sphere from passing between the cables when they are properly tensioned in a well-designed frame.


Used this type of railing system on a Commercial Project, (no photos) before, and the above description is accurate.
You can not spread the cables inbetween supports.

That right there seems to be the most important design point. You can tighten them to the point of being mostly immobile, but if they are shorter it takes a lot less tension.

There is a course on this at and it explains all what Marcel has pointed out and even the cable being next to impossible for a child to climb.
They use them in High end buildings everywhere.

Mike, if you click on the oaconstruction link in my signature, go to Project Gallery and click on the Industrial link and then George & Barbara Bush Center/UNE and the pictures will show you a cable railing.

Look how close the rail posts are.

That is all that is needed in the photo you supplied.
Intermediate cable guide. :slight_smile:

Great link, thanks Kevin…Continuing Education courses…

In the NBC It say that the top 32" of the rail cannot be climbable. Not sure of the IRC but most of the time they are parallel

I don’t like it at all for many reasons:

  • Ladder effect (I count 5 rungs on less than a 3’ high rail… that’s more rungs/foot than the ladder I use).
  • Child spacing (I’m sure the cables spread in the middle).
  • Tension will bow the top rail (and if it bows the top rail down, the middle may no longer meet rail height requirement).
  • Two cables running parallel (as you tighten one, the other is going to loosen).
  • Style (too eclectic).

Nick even though you dont like them does not mean they have not been accepted. Reason is they cannot find any documentation of kids trying to climb them successfully I guess.
The cables are not easy to hang onto and it takes allot of effort just to hang on with your hands to climb not to mention coordinating that with stepping on the cable.
The cables are placed at 3 inches not 4 on some manufacturers so there is no way for a kid to get his head stuck.
But since this is BS go take the course and see.

DEFECT: Railing Ladder and chocking effect.
RECOMMEND: The cables be enclosed using material/s to fit personal aesthetic taste and meet all safety requirements.

Although the ladder effect was removed from the IRC, many municipalities still use the 2000 IRC where horizontal members in guardrails are prohibited.

However, my job as a home inspector isn’t to sort that all out, figure out if it is accepted by the AHJ or not, or to figure if it is up to code or not. My job is to report potential issues that I deem material.


I point out climbable deck railings and explain potential issues.

It is up to my client to decide if they are important to them.

Interpreting the hazardous nature of any decorative or non-vertical railing & components is an all or nothing proposition. The safest courses of action are to either call them all out as potentially hazardous or defer them all to the local AHJ. (or both) This would not be an area where a railing by railing evaluation should occur.

Personally IMO kids are more likely to climb on furniture and take a dive off the deck when unattended. But stupid parents and self-destructive children need to be protected from themselves.

Cameron you must have read the continuing education on the climbing rail debate. Am I correct or is this what you feel?
I am just asking and don’t want to get in long debate.