Are your firestop submittals missing something for shafts? (part 2)
In our last blog post, we talked a little about shaft walls, what they are made of, and some things to keep an eye out for. Are your firestop submittals missing something for shafts? We will build on that as we go.
Today we are going to look at firestop submittals as they relate to shaft wall assemblies, so the next time you are reviewing project documents you will have a better idea if something is missing. The easiest way to understand this discussion is to quickly review the UL nomenclature post found here so this will be easier to follow. If you do not know this nomenclature its much more difficult to conduct this exercise.
First let’s think about the RATED JOINTS. Let’s assume that the project has both block shafts and gypsum shafts. As you look at the firestop submittals pull out the HW (head of wall) details and look for the types of shaft walls you have on your project. For this discussion we will assume you have both gypsum and block shaft walls.
GYPSUM WALL:
You will likely have a handful of HW details but if you have gypsum shafts you need to be sure the project has a detail for firestopping this gypsum shaft. Are your firestop submittals missing? WL details for gypsum walls differ from standard details because shaft walls require different construction and firestopping.
This will require sealant at the shaft liner as well as on the outer layers of drywall. If you firestop this wall type after the wall construction is complete, the system will not be compliant because it will only have protection on one side. This would create a major liability for the installer as well as the GC, building owner and building occupants. If you are looking at a WL2000 series detail for plastic pipes, be sure to take a closer look, but do the same for all your penetration types.
BLOCK WALL
If you have access to both sides of the wall, as you would in an elevator shaft, then it is easy to firestop the head of wall joint on a block wall from either side of the wall. Likewise you can firestop your through penetrations with either a CAJ or WJ detail. If you only have access to one side of the wall, you will need what is commonly referred to as a sandwiched detail and my guess is that it will likely be a WJ detail or possibly an engineering judgement.
This allows firestop installation in four steps. Typically there would be installation of mineral wool recessed maybe 4-1/2” into the joint, then firestop sealant (let’s say it calls for ½” of sealant) then another layer of 3-1/2” of mineral wool followed by another ½” of sealant. There are 4 steps to this installation, which means 4 steps to any firestop inspection as well, unless the inspector wants to try to cut into this kind of joint application, which is going to be a challenge in and of itself. This means the firestop detail must show one-sided installation if that’s how the installers will proceed.
Verify that the block wall firestop detail in the submittals is installable, as expected in the field. Are your firestop submittals missing? Is it physically possible? Ensure there’s a head of wall, bottom of wall, and possibly a wall-to-wall detail for the gypsum assembly. It is not uncommon for a contractor to miss these details, so be on the lookout for them.
Next, think about the penetrations going through your shaft walls. Block and concrete walls often lack access from inside the shaft, so installers usually require a sandwiched application. However, some devices can be installed from one side.
If we’re working together, we can help choose the best manufacturers’ products for different scenarios. If your stairwell walls are block or concrete, firestop details typically start with CAJ, WJ, or WK for thicker walls.
For sprinkler pipes and conduits, you’ll need a 1000 series detail. If you have plastic sprinkler pipes, you’ll need a 2000 series detail, plus a 3000 series for your MC cables. You won’t need a 7000 series detail for ducts through a 2-hour wall, as they will require dampers.
Finally, review these details to ensure they allow one-sided access if only one side is available for installation. If not, you’ll need an Engineering Judgment. And remember, if you’re in NJ, DCA does not allow EJ’s—sorry NJ!
Typically firestop installers will submit details for the various penetrations through a standard wall. They may be acceptable if the listed detail allows the shaft wall type. If included, you’re fine; if not, they must submit a new detail. You will find this in item 1 of all details. These details begin with WL for gypsum framed walls. For mechanical shafts, WL 1000 is for metal pipes, WL 5000 for insulated pipes, and WL 2000 for plastic pipes. During installation or inspection, check the annular space and sealant depth to ensure they match the details. Ensure the installer firestops the shaft liner side before installing the outer two layers of drywall.We’ll cover this in a later post.
We’ve highlighted a few things to watch for. In our next post, we’ll dive deeper into this and the building code. If you have questions about a recent firestop submittal please contact us for help.