You are Building in a Seismic Zone? Read this for Part 2 of 2
Our last blog post discussed clearance requirements for sprinkler pipes when you are building in a seismic zone. The NFPA and the damper manufacturers use the phrase clearance. The firestop industry uses the term annular space and defines it as the distance from the outside edge of the penetrating item to the inside edge of the opening in the rated assembly.
Firestop applications often refer to a minimum and maximum annular space. Most of the time, pipes do not center themselves in the opening. This usually does not cause problems with most applications. However, the NFPA requirements we discussed in the last post present a different scenario. For example, an 8” sprinkler main requires a 12” opening.
Centering the pipe in the opening requires the firestop detail to have roughly 2” of annular space. This is usually not an issue. However, when reviewing firestop submittals, ensure the annular space of the firestop details meets the code requirement. But that is not realistic to have the pipe centered in the opening all the time. Prepare for the worst-case scenario where the pipe might shift to one side of the opening. Ensure your firestop submittals account for this possibility.
If the pipe is completely askew you may have as much as just shy of 4” of annular space o contend with. Well, really it will be less because even if you have an 8” pipe and a 12” opening the outside diameter of an 8” steel pipe is going to be close to 8-1/4” so that would make the maximum annular space around 3-3/4.
Most firestop manufacturers have fantastic websites to help you find the details you need or you can call them directly and talk to their tech team for additional support.
When you are building in a seismic zone and conducting your firestop submittal review you need to be sure that your firestop details can meet this requirement, or that you have seismic couplers on both sides of your rated walls and floors and any “non-frangible” substrate.
Two other things to look for when comparing the firestop detail to the field condition:
- Sleeve: Did the use a thin gauge tin sleeve? Is that allowed by the detail? Firestop details often list a sleeve as optional. However, some documents either do not mention the sleeve or specifically require it. If a sleeve is allowed or required check to be sure the gauge in your paperwork matches what they used in the field. A thin gauge sleeve will have different fire dynamics compared to a heavier gauge sleeve, so treat them differently. So, to make this simple for you just remember, you need to look for 2 things:
- Is the sleeve allowed or possibly required?
- Does the gauge match?
- Support Bracket: If you find firestop smeared all over the bracket, it indicates that the firestop was already in place during installation. Although this might seem basic, it suggests that someone may not have installed the firestop properly. Check back on our next post for more details on this.
If you have problems or questions, don’t hesitate to contact us for help as well.