Firestop in Shafts is Often Done Wrong, so Someone Asked, “How do We do it Right?” (part 3)


If you were with us for the last two blog posts you saw that there is a lot to look at when dealing with plastic pipes, and even more to deal with when those plastic pipes are going through a gypsum shaft assembly. Today we are going to tackle the concrete or block wall applications.  The shaft walls were not so bad, as long as it was staged/planned/schedule appropriately. Concrete or block walls however don’t have this same luxury and often have to be firestopped from one side.


When we were talking about the WJ1000 series details for our metal pipes I was able to share with you some relatively newer tests that were tested for a one sided installation.  Before those were available the typical option was to use an engineering judgment that often required mineral wool recessed well into the wall, maybe ½” depth of the firestop sealant, followed by more mineral wool and another layer of ½” depth of firestop sealant.  This was providing the same basic installation materials in a slightly different order and from one side of the wall.


Plastic pipes are tougher because they are combustible. If you remember the time temperature curve, then you remember that the temperature inside the test furnace must be 1000F at the 5 minute mark. Plastic pipes melt between 200F and 500F, which means in no time flat the plastic pipes will be gone. Insert time temp curve


This means that firestopping from one side is going to be more of a challenge and the larger the pipe, the greater the challenge. One great way to tackle this challenge is with another one of my favorite problem solving products that you can see here.


This is a metal sleeve with sheets of intumescent material. It comes flat, so if you are installing it say on a 4” pipe, its best to grab a 2” pipe. Wrap the sheet metal and the wrap strip around the smaller pipe, then uncoil it and it snaps easily around the 4” pipe and you can slide it into the opening.  I do not normally suggest the use of an EJ but as we walk through the detail you will see why it is needed. (but with any luck Metacaulk will test this as a one-sided application so you don’t even need an EJ)


For this review let’s look at WJ2274.  This particular detail is for Aquatherm Blue Pipe.  We mentioned a little bit about this polypropylene pipe and others in previous blog posts. We just want to remind you that this is a unique product and since this detail is for Aquatherm blue, SDR 17.6 then it is limited to this material and this material only.


I am going to throw out a handful of questions for you and Wednesday I will share the answers with you.  The questions don’t all relate to the same field application.


Question 1: My field condition has a sleeve in a block wall. I can still use WJ2274 because the firestop device is a sleeve, right?


Question 2: What kind of anchors do I need to use to secure this to the wall?


Question 3: My field condition is using Aquatherm SDR 11.  It’s the same brand, so I can still use this, right?


Question 4:  The sleeve I am using is 10” long and I don’t want to see it on the occupied side. Is it okay to push it in flush with the outside of the wall?


Question 5: We are using brand X firestop sealant and we don’t want to have another sealant on site to confuse people with, so its okay if we use brand X firestop with this new sleeve thing, right?


Question 6: The aquatherm pipe is insulated but I got sleeves that are big enough to go around the outside of the insulation so this is fine, right?


Question 7: I am using 3” Aquatherm green. My hole is 5” and I have ¼” annular space on one side around 3 o’clock. Can I still use this detail and this product?

See this chart for product information