Plumbing Chase vs. Shaft

Q: What are the code requirements for penetrations in plumbing chases? During the water fountain project we found openings in the floor in the back of the plumbing chases from the original construction in 1949. Pluming lines pass through these openings. Is it required that these penetrations be fire stopped.

A: It depends…Were you looking at chases or shafts? A ‘pipe chase’ is where pipes run vertically from one story to another story, internally to the building, and the deck between the two stories is sealed over and meets the requirements for fire-rated construction for the horizontal barrier (i.e. floor). The vertical pipes penetrating the horizontal deck are sealed with proper fire-stopping materials. If the pipe chase has any vertical walls to protect the pipes, they are not required to be fire-rated and any pipe penetrations though these non-rated chase walls are not required to be fire-stopped.

A ‘mechanical shaft’ may look similar to a chase, but the horizontal deck between the stories is open and there is no attempt to seal the opening between the two stories. This means the vertical shaft walls must be fire-rated and any penetrations through these fire-rated shaft walls must be properly fire-stopped. Also, any HVAC duct penetration through a vertical shaft wall must have a fire damper at the shaft wall opening, regardless of the fire-resistance construction of the shaft walls.

So, you say you found openings in the floor, and since you could see them, that implies there were no vertical fire-rated walls concealing the shaft. So, it sounds like you have a serious breach of the horizontal barrier (i.e. floor) that needs to be repaired back to the original intention of the building. If these are small holes, then proper fire-stopping materials would likely be acceptable. If these are large holes, you may have to reconstruct the floor in that area as fire-stopping materials are only valid for a certain size opening.

Strange Observations – Gypsum Patches

Continuing in a series of strange things that I have seen while consulting at hospitals…

Holes in rated walls that are too large to be sealed with fire-rated materials, cannot be ‘fixed’ with a gypsum board patch, as shown in the picture.

However, there is a UL system W-L-0014 that does permit installing gypsum patches over holes in rated walls, but it requires an equal-sized patch on the opposite side of the wall, along with other requirements, such as 3-inch long screws with fender washers. The W-L-0014 system is part of the Hilti Firestop System library of listed products.

Mixed Fire Caulks

Q: In the past our hospital has used different brands of fire caulk on the same fire wall assembly. The fire caulk is two different brands and different colors and surveyors have stated that we cannot have “mixed” caulk. Where in the Life Safety Code does this say we cannot mix fire caulks?

A: There is no specific Life Safety Code reference that speaks to this, but the surveyors are correct. It has more to do with the UL listing of the fire-stop assembly where the mixed fire caulks are used. A proper fire-stop system is an assembly and must comply with the UL listing that it was tested to. For example; to seal a penetration in a fire-rated wall, the UL listing will identify what type of fire caulk to use, what material it is permitted to be used on (i.e. gypsum board or cement block), and how to apply it. The UL listing is typically specific to the brand of fire caulk material used. This is because the manufacturers pay to have Underwriter’s Laboratory test the assembly and the resulting UL listing is specific to their brand of fire caulk. There is no UL listing for when you mix the different brands of fire caulk on the same assembly. Will it work? Most likely it will, but it does not meet the UL listing of that particular assembly. This is why there is a movement in the industry to have the installers who install fire-stop materials be certified to do so. Education is needed so the installers fully understand how to properly apply the products.