GOLDILOCKS AND THE THREE SLEEVES (Part 4 on sleeves)
Not all of my audience is American, or even Western so allow me a moment to explain a children’s story called Goldilocks. There is a family of bears. They are Momma bear, Papa bear and baby bear and they all went out for a walk before breakfast. A little girl walks into their house and eats from their bowls, sits in their chairs and naps in their beds. One is too big, one is too small and one is just right.
That is the theme of our discussion today. Getting the size just right and the consequences of not getting it just right.
Let’s say the sleeves in this discussion are going to match whatever heavier gauge is required so we will be focusing on the size of the sleeve rather than the gauge or material used in the sleeve because we have already discussed the impact of the gauge and we will later discuss the various options for materials that need to be used for sleeve applications.
What size sleeve would you use if you have a 4” pipe that will be insulated with 2” insulation?
Wrong move #1:
The guy laying the sleeve looks at the numbers and figures 4” pipe plus 2” insulation (4+2=6) so we use a 6” sleeve. In this scenario there won’t be enough room for the pipe AND the insulation because the insulation is on both sides of the pipe so the equation is 2” of insulation plus, 4” of pipe, plus another 2” of insulation on the other side of the pipe.
A 6” sleeve only give 1” on either side of the pipe for insulation and firestop so even if the insulator uses 1” insulation where the pipe goes through the wall there still is not enough room for the firestop that is needed and if you firestop with typical intumescent firestop sealant (material that expands when exposed to heat), then the firestop will expand away from the opening and will not have any positive impact in a fire scenario. The material needs to be lodged between the inside edge of the opening and the outside edge of the insulation so that it can either compress the insulation against the pipe or fill the void when the insulation melts or burns away. If the firestop is not placed properly it will not react properly.
Depending on the R value required for the insulation, the risk of condensation and other variables, the solutions will vary. Some projects have opted to allow the mineral wool insulation count as pipe insulation since it often has the same R-value and the insulation is removed just where it goes through the wall. This is the cheapest solution from both a labor and a materials standpoint. It often causes problems for the building owner and those problems will vary depending on the reason the insulation is needed, so when making a decision these factors should be weighed.
If this is done be sure the installation is firestopped with a 1000 series detail and not a 5000 series detail. See here for more information on selecting the correct UL listed detail for various applications. See here for more information about firestopping to different types of pipe insulation.
Next week, we will discuss option sleeve option sizes and more potential solutions for this sort of problem installation.
How can you avoid this problem and many others?
When HLS conducts pre-construction meetings this is one of the many things we cover BEFORE construction starts. The meetings include our the MEPS subs as well as the drywaller, insulator, masons, carpenters and the CM or GC teams. We have a separate meeting to cover edge of slab firestop which has its own unique complications. Our clients tell us our pre-con meeting is a game changer for the project because the entire team is looking at firestop in a new light and everyone understands their impact on the life safety of a building. More importantly everyone understands a new level of accountability. That is just the beginning of how things will run on your next project if HLS is on your team.
If you are interested in learning more about our proven method, please contact us.
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Our mission is to make a colossal impact on the level of life safety of your building and on the talent of your people. We provide consultation, training, quality control and third party special inspection related to firestop and passive fire protection. We consult for the building industry in the New York/New Jersey (NY/NJ) metropolitan area, as well as across the United States and internationally.