The answer to this question depends entirely on your UL listed detail. Here is the verbiage pulled from a random UL listed detail that allows for a plastic sleeve.

Nonmetallic Sleeve – (Optional) – Nom 6 in. (152 mm) diam (or smaller) Schedule 40 polyvinyl chloride pipe sleeve cast or grouted into concrete flush with both surfaces of floor or wall.

So, clearly with this particular detail, it is possible to firestop to a plastic sleeve. The key is whether or not the detail you are using will allow it. It needs to. If it doesn’t then you either need to modify the field condition to match the detail, or you need to get a detail that matches the field condition; even if that means obtaining an engineering judgment.

Here are some things to think about if you have a project using plastic sleeves. For this discussion we are going to assume the sleeve is placed in a rated concrete assembly and not in a gypsum assembly. If you have questions about plastic sleeves in a gypsum assembly feel free to reach out to us for help.

More likely than not, the firestop detail will state that the sleeve MUST be flush with the surface of the concrete. If it isn’t, then it is likely the detail will require that the firestop must be recessed into the sleeve to the point that it is in the same plane as the concrete.

Why does this matter? If the plastic sleeve is not flush with the wall and the installer firestops to the outside edge of the sleeve, can you picture what will happen when the plastic pipe melts?

Depending on the type of plastic, it will begin to melt at temperatures between 200 and 500 F. Under the fire test conditions, this is fewer than 5 min into a 1 hour fire test, regardless of the type of plastic pipe you are talking about. The plastic pipe will melt away and take with it the firestop that is not secured in the opening of the rated wall.   This will leave a void in the rated assembly through which fire, smoke and toxic gasses can pass prematurely. If the firestop is installed in the same plane as the rated wall then, when the intumescent material begins to expand, it will be contained by the concrete and it will be able to maintain the integrity of the rated assembly.

One thing we often see on projects are the plastic sleeves used to hold the formwork together when concrete is poured. There are three different scenarios we have seen that have been used to resolve this breach in a rated wall. If you do something different on your projects, please let us know.

  1. Often times these are filled with grout and many inspectors are okay with this. The judgment is based on the fact that the code allows openings to be grouted back if they are less than a certain size (“shall not exceed 6” dia”…”shall not exceed 1 sq ft”*) and this application is well under that. However the section of code allowing this does not mention grouting inside a sleeve, let alone a plastic sleeve that would be combustible.*
  2. Other projects have required the plastic to be removed a certain depth and the remaining opening to be grouted in. The problem here (and above) is that the code requires that “the thickness of the concrete, grout or mortar shall be the full thickness of the assembly” and this is not going to be a viable solution if your inspector calls out this code section. If they do, contact us and we can help you navigate the code for a better solution*
  3. It is possible to get an engineering judgment or maybe even a tested assembly depending on the manufacturer being used on the project.

* NFPA 2012 similar verbiage can be found in the IBC as well section 714.4.1.1…Now please keep in mind that both sections of the code noted here are in areas where they discuss PENETRATIONS and in most jurisdictions the sleeve is considered a penetration and despite the fact that this section of code refers to metal penetrations the AHJ’s in my experience have tended to allow this section of code to be used despite the fact that there is no metal penetration. Check with your local building officials if you have any questions because they are the ones who can give you the answers to what will work in your area.

In the grand scheme of firestop problems this ranks lower on the list than many others but since we are having a discussion about sleeves and in particular plastic sleeves, we thought that this should be noted.

If you find we have missed something in the discussion of firestop sleeves please let us know and we will gladly add your voice to the discussion. If you have additional topics you want us to discuss, please let us know. If you have a project you want us to look at we are happy to help make your project better. We travel the world to help ensure projects get their firestop right. You will be hard pressed to find someone who enjoys THIS scope of work more than we do. Let us help make sure none of these problems, or a long list of other common problems do not crop up on your next project.