I have leveling my slopped backyard. In order to leveled it, the retaining wall will be 5.5' tall and 20 feet long. we are using AB classic (8 in. H x 12 in. D x 18 in. ) weight 75 lbs.

Is it ok go with mounting 4' high railing on wall's cap.

I am thinking to install Cable railing.


  • I saw a design where instead of one big retaining wall, they used two smaller ones for a terraced look. Then railing were not needed, it was code compliant and looked nicer. Feb 4, 2022 at 5:48
  • Is "AB classic" some sort of retaining wall block that you'll be setting? Have you designed the wall yourself or is there an architect/landscape designer/engineer type involved in the design of the wall?
    – FreeMan
    Feb 4, 2022 at 13:40
  • @steve wellens. I don't want to build retaining wall for just look nicer. I need space so that my kids can get plenty of space in leveled area to play.
    – PowerTech
    Feb 4, 2022 at 14:23
  • @FreeMan, Yes. But I'll be building the wall through a contractor company. DO i need hire an engineer even though i am building through a company ?
    – PowerTech
    Feb 4, 2022 at 14:25

1 Answer 1


If this is a big, well known firm that does landscaping, wall building, etc., odds are really good they've got someone who knows enough to get a 5.5' tall retaining wall right or they'd have been sued out of existence long ago. They've probably got an engineer with the proper licenses on staff (or retainer) to do and sign off on the work in order to get permits approved and to meet their insurance requirements.

If, on the other hand, it's "Bob's Handyman Service", there's no telling whether or not they have knowledge of, or respect for, the engineering and building codes that goes into making a safe and secure retaining wall that will last.

The remainder of this answer presumes you're using a contractor from the first category, not the second.

I would be sure that they know you want the railing on top of the wall cap and the kind of railing you want. Have them design it into the structure so that it will be properly supported. I'm not sure if you're planning on building the railing yourself or having them build it for you. If you're going to DIY after they're done, they may be able to build in posts for you or places for you to put the posts so that they'll be properly supported and the wall will be designed for the stresses that may happen there.

If you try to add it on afterwards, you may run into issues with securing the railing to the top of the wall and/or compromise the strength/stability of the wall leading to a potential collapse. Also, any work you do afterwards will likely open you up to the liability of a wall failure instead of leaving it with the company.

Also, you might consider making two terraced steps (as noted in Steve Wellen's comment to avoid needing any sort of railing/fencing at all. Where I am, a deck that's less than 30" above the ground doesn't need a railing (though ours looked odd without one, so we added one). The requirements for a landscape terrace may be similar where you are. If you add a second terrace so that neither wall is more than the "no railing required" height, you could get away without a railing and it may end up looking better. I'd assume that the cable railing is to minimize the impact on the view, so no railing would be even less impact.

You don't need a huge area for the lower terrace - maybe only one foot wide so that it doesn't encroach any more than necessary on the surface area of the top terrace. It would consist of the wall itself, then the exposed area between the lower wall and upper wall could be covered with gravel so you don't have to deal with dropping the lawn mower down there to take care of a narrow strip of grass. Perennial plantings (with small roots, so as to not destroy the walls) might be an option, too.

Two shorter walls may be less expensive to build and may (mostly? completely?) offset the cost of the single taller wall and railing system. These would be questions to address with your builder.

  • Thanks for Answering my question. As I mentioned above. I am building wall to get enough space for kids to play. If i am going to have two terraced steps. I won't get that much. then Its waste of money even though with two terraced steps.
    – PowerTech
    Feb 4, 2022 at 16:57
  • My contract company says, I don't need to take permit. So I forced them to take permit ?
    – PowerTech
    Feb 4, 2022 at 16:59
  • Needing a permit has nothing to do with the quality of the up front design and workmanship put in. This question revolves around adding a railing to the wall - talk to the builder about doing so before he starts work. Ensure that the design will handle adding the railing and make sure you know how to attach it to work with the design of the wall and not jeopardize the work. I presume you got several bids and are working with a company you're comfortable with, so rely on them to prepare your wall for the additional railing.
    – FreeMan
    Feb 4, 2022 at 17:09
  • The code requires a 200 lbs. be supported at the top of the wall.
    – Lee Sam
    Feb 4, 2022 at 18:39
  • Oops…that 200 lbs. force is to be applied horizontally. (Sorry about that.)
    – Lee Sam
    Feb 4, 2022 at 23:42

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