Lessons Learned: Why Reinforcing Steel Doesn’t Belong in Cast-in-Place Coping

Cast-in-place coping can be used to create a wonderful, clean-looking edge treatments, but like all construction details on pools and other structures that hold water, what you don’t know can lead to problems. In this case, it might come as a surprise to some that “doing it right” means leaving out the steel.

By Scott Cohen

In watershaping, we’re trained to think—correctly in most situations—that concrete and reinforcing steel go hand in hand. After all, steel is essential to structural integrity in pool shells, decks, walls, and foundations. But not all concrete applications require steel—and in some cases, like cast-in-place coping, adding rebar can actually do more harm than good.

Let’s break down the reasons why reinforcing steel has no business in cast-in-place concrete coping, and how contractors can get better results—legally, structurally, and aesthetically—without it.

THE COVERAGE CONUNDRUM

One of the most common misconceptions I see in the field is the belief that coping, like decks or shells, needs structural reinforcement. But coping is decorative, not structural. Its strength and integrity come from the pool’s bond beam, not from within the coping slab.

Think about it: we use precast, stone, or even pavers as coping all the time—and none of them contain steel. Why would cast-in-place concrete be any different?

Rebar in concrete needs a minimum of two inches of coverage to be compliant with the California Building Code (CBC) and International Building Code (IBC). These standards are in place to prevent corrosion and ensure long-term durability, especially in environments where moisture and chlorides (like swimming pools) are ever-present.

Now here’s the catch: most cast-in-place coping is only about three inches thick. That means you simply can’t provide the required two inches of coverage on all sides of the steel. If it’s centered, you’re out of code. If it’s closer to one surface than another, it’s going to rust—and fast. When you score the joints, the steel is even closer to the surface of the concrete.

Moisture seeps into concrete—especially in unsealed coping—and the first place it attacks is the steel that’s too close to the surface. This leads to rust that can spread through the concrete and blow out on the surface, permanently damaging the coping. It can result in cracking, and delamination, not to mention potential bonding violations if the rebar isn’t electrically tied into the pool shell (as required within five feet of the water).

Here’s another common failure point: even when rebar is included in cast-in-place coping, the steel doesn’t shrink—but the concrete around it does. This mismatch often leads to hairline cracks that follow the rebar layout—a telltale sign of poor consolidation, reinforcement placement and too much mix water.

I’ve seen it happen in countertops, benches, and especially in coping, where weather exposure only magnifies the issue.

DO IT RIGHT

If you’re going to pour cast-in-place coping, skip the steel and do it like the precast manufacturers do:

1. Clean the bond beam and moisture condition the surface of the concrete.
2. Set the forms, and apply a mold-release to the forms (not the bond beam).
3. Brush on and work in a cementitious slurry as a bonding agent.
4. While the slurry is still damp, use a low-slump (dry) concrete mix for greater strength and less shrinkage.
5. Mechanically vibrate the mix into the forms to consolidate the concrete, reduce air pockets and improve the finish. This often overlooked step dramatically increases the strength of the concrete and reduces shrinkage cracks.
6. Strip the forms while the concrete is still green and finish the edges by hand.
7. Score your control joints every 1.5x the thickness of the slab (e.g., every 18 inches for 12-inch-wide coping).
8. Cut the control joint a minimum of ¼ of the slab thickness deep to guide cracking where you want it.

Using this method, I’ve consistently produced coping with excellent finish quality, improved strength and far fewer long-term maintenance issues.

We typically use cast-in-place coping when we’re working on custom freeform designs where precast can be problematic. But for straight-line modern designs, precast is usually the better bet.

You can’t match a custom concrete pour five years down the road—but you can replace a damaged precast unit and get a perfect fit. There are so many variables in terms of site conditions and slight variations in material that even if you’re using the exact same mix schedule and application techniques, that simply due to the fact that you’re doing the work on different days, you’re never going to be able to achieve an excellent color match.

Whenever pouring coping on site, I recommend fabricating a few extra pieces to use for future repairs if necessary. Color consistency article link.

STEEL FREE

The takeaway here is simple: don’t use steel in cast-in-place coping. It’s difficult to meet coverage codes and bond it reliably. It will often rust, crack, and may fail. Quite frankly, you don’t need it.

If your concrete crew insists otherwise, remind them: not all concrete needs steel, especially not decorative concrete. Stick with best practices, understand your materials, and let the bond beam do its job. You’ll avoid callbacks, costly repairs, and structural misunderstandings—and deliver cleaner, longer-lasting results your clients will love.

And please—for the love of durability—put down the chicken wire.

Scott Cohen is a nationally respected expert witness in pool-construction defect cases. He is a “garden artisan” and president of Green Scene Landscaping & Pools, a watershape design and construction firm based in Chatsworth, CA. A widely published author and popular speaker, Cohen is known for his gardens that combine outdoor living with inspired artistic details.