The last post talked about the problems with selecting a sleeve size without considering the depth of the insulation correctly. This posting will continue the discussion of common errors and potential solutions. Please read the last few posts if you have not already because we are building on what has already been discussed.
We are making two assumptions:
1) We assume you are going through a rated wall, because otherwise firestop is not part of your discussion. If the wall is NON rated this sleeve size might be acceptable, but in a rated wall you have issues with regard to the annular space requirements.
2) We are assuming the application is going through concrete. If you are going through drywall, then the opening should simply be enlarged and firestopped correctly.
Wrong move #2:
Our next scenario the contractor decides that 2” insulation plus a 4” pipe and 2” more of insulation means they will need an 8” sleeve. Many details will require SOME annular space, and even the details that call for 0”-2” annular space will not allow for CONTINUAL POINT OF CONTACT (stay tuned for a blog on when you can allow continual point of contact) which is what you will have in this scenario. Having adequate annular space is key to the installation working as expected. For now let’s just say that the annular space impacts the volume of material that can be installed and the volume of material will impact the results in a fire. While you may have a detail that allows for point of contact it won’t allow for continual point of contact because some sealant needs to be installed. So this means the sleeve is going to look really goofy when just the bare pipe is going through it. It is going to look incredibly over sized since it needs to be more than 2x the size of the pipe.
Potential fix #1:
Our last post, talked about a potential fix being using the mineral wool required in the firestop installation in lieu of the pipe insulation. Before doing this be sure to review the specifications because this may not be allowed and for various reasons it may be a bad idea, but that is for the mechanical and plumbing guys to deal with.
Potential fix #2:
It may be possible to use the insulation but to reduce the thickness where the pipe goes through the wall so that the firestop materials can be used and conform to the UL listed assembly. Again check with the plumber or mechanical contractor for their professional input.
Potential fix #3:
No one will like this solution, but it’s still worth noting if this problem is caught before the pipe has been run. The contractor can core the hole bigger so it can accommodate the appropriate installation. Then you would eliminate the sleeve all together, so be sure your firestop system will allow the new field parameters. Remember that the details in your firestop submittal need to match the field conditions.
Potential fix #4:
There are a number of variables that can be considered so if none of these solutions work to resolve your problem please contact us and we will see if we can not help you find a better solution based on your particular circumstances.
Resolve the problem early- pick the right sized sleeve:
So, for a 4” pipe with 2” insulation you are going to need to use a 10” sleeve. That will only give you 1” of annular space (assuming that your pipe is centered in the opening- if it is off center then you are likely to have min 0” max 2”- but again you won’t have continual point of contact because that would likely result in a non-compliant installation. Contact us at email@example.com or call us at 201-250-4193 and we will walk you through some potential options. We won’t address it on this blog because there are too many variables to getting this right and you would be reading forever. Just call us, and we will figure it out together.
If you want your construction team to be more aware of these topics before, during and after construction; then we can help. We have conducted countless training seminars for architects, engineers, inspectors and a wide array of construction staff. If you are interested in learning more, building a stronger team and making sure your projects perform better in the event of a fire; please contact us to arrange for a training program.