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Chip's Tips - HydroFlame Pro Series and Topping Slabs


First, what is a topping slab?

  • A topping slab is a secondary concrete slab layer that is poured on top of a pre-existing concrete slab.
  • This often happens in an area of the building where there is need for a fairly dramatic sloping floor, or in an exterior planter or plaza area where a waterproof elastomeric membrane is poured and then the topping slab is poured to create architectural features or sloping areas to planter drains or plaza drains.

Whatever the case, if a topping slab is going to be added, the process of sleeving is typically accomplished as a two-step process:

  1. The first step is to position the firestop sleeve on the form deck and pour the concrete (like a typical sleeve installation).
  2. The second step, just prior to pouring the topping slab, is to remove the safety cap from the first sleeve (save it for re-use) and install the sleeve extension into the threaded outlet of the original sleeve and set the extension to the desired height. Next, replace the safety cap and pour the concrete.

Sometimes this is easy and sometimes it is not, depending on the thickness of the topping slab.

Let’s look a couple of scenarios

If the topping slab is 4-3/4 in. deep. That’s an easy one.

HFP step 1

After the lower concrete slab is poured and it’s time to prep for the topping slab, remove the safety cap.

HFP step 2

Screw on a sleeve extension.

HFP step 3

Re-install the safety cap, pour the concrete.

If the topping slab is 6 in. thick:

HFP step 4

After the lower concrete slab is poured and it’s time to prep for the topping slab, remove the safety cap.

HFP step 5

Insert a portion on an inner sleeve into an outer sleeve and re-use the safety cap.

HFP step 6

Place this assembly into the sleeve that is cast-in-place, locking it in place at the appropriate height (in this case, 6 in. above the slab).

HFP step 7

(Optional) Wrap tape around the joint between the two assembled pieces, to block concrete from getting between the two sleeve parts. Pour the concrete.

What makes all this possible?

It is the fact that we intentionally made all the male and female threads in the various HydroFlame Pro Series sleeve components interchangeable. This allows for some real creative assembly options, like the ones we discussed above. If you need help with another unique scenario don’t be afraid to ask for help. Nearly any sleeve height combination is possible when planning ahead.