Firestopping combustible pipes

The firestopping of combustible pipes has always been a soft spot

for plumbers and inspectors. The National Building Code of

Canada and the code in my part of Canada (Ontario) are very similar

in requirements, but do share a few differences.

Since plastic piping systems are used so widely in construction today,

I’ve teamed up with Kevin Yong-Ping, one of IPEX’s engineers, to

raise the awareness of firestopping best practices as they relate to

combustible pipe penetrations.

So, let’s take a look. Both the 2015 National Building Code and 2012

Ontario Building Code explain that, aside from a few

exceptions, any time a fire separation or a membrane

that’s part of a fire separation assembly is penetrated by such things as

pipes, vents or conduit, a firestop needs to be used or the penetration

needs to be cast in place.

Note that there is an F rating requirement with firestops. These are based

on tests outlined in CAN/ULC-S115, and details of the requirements can

be found in Table 3.1.8.4. in your code book.

Where these penetrations are horizontal, there is an FT rating

requirement, also based on CAN/ULC-S115, and this generally requires

the firestop to have a resistance rating equal or greater than the rating of

the firewall or fire separation.

An exception to these requirements is extended to sprinkler systems,

provided that the annular space created by the penetration is covered

by a metal escutcheon plate. Some fire dampers are also permitted to

penetrate a fire separation, provided that they are installed in compliance

with NFPA 80.

When it comes to combustible pipe penetrations, you’ll find these in

section 3.1.9.5 of the National Building Code, and 3.1.9.4 in the Ontario

Building Code.

When talking about this with your local inspector, don’t get the reference

mixed up. In Ontario, 3.1.9.5 is “openings through a membrane ceiling.”

The Ontario code outlines the specific cases where

combustible piping can penetrate a fire separation required to have a fire-resistance rating, or a membrane that forms part of an assembly required to have a fire-resistance rating. Again, with a few exceptions outlined in the code book,

combustible piping is permitted to penetrate a fire separation

required to have a fire-resistance rating or is permitted to

penetrate a membrane that forms part of an assembly

required to have a fire-resistance rating, provided the piping

is sealed at the penetration by a firestop that has an F rating

not less than the fire-resistance rating required for the fire

separation, as per the fire test method in CAN/ULC-S115. A

pressure differential of 50 Pa is required between the exposed

and unexposed sides, with the higher pressure on the

exposed side.

Combustible drain piping is permitted to penetrate a

horizontal fire separation, provided it leads directly from a

non-combustible water closet through a concrete floor slab

and the piping is sealed at the penetration by a firestop.

Combustible piping can also penetrate a vertical or horizontal

fire separation if both sides of the separation are sprinklered,

and an appropriate firestop seals the penetration.

For public pools and spas, there’s also an allowance for

combustible piping containing chlorine gas, provided that

the piping is not more than 25 mm in diameter, and that an

appropriate firestop is used.

With all of these uses, check your local code for the

appropriate FT rating to ensure that the firestop used

conforms to requirements. And, where necessary, watch

to ensure that the firestop test is tested with a pressure

differential of 50 Pa between the exposed and unexposed

sides, with the higher pressure on the exposed side. Also

review whether the fire compartments on each side of the

firewall or horizontal fire separation need to be sprinklered.

Upholding the integrity

In essence, if you’re penetrating a fire separation with either noncombustible

or combustible piping, you’ll need to uphold the integrity of

that fire separation, and thus provide a valid firestop listing that matches

your site conditions. For plastic piping, you’ll find that there are a variety

firestop product options available. Through-penetration firestop products work by

filling the voids around penetrating items in fire rated walls and floors.

When combustible products are used, these firestop products “intumesce” or expand

in the presence of heat, thereby sealing and stopping the spread of flames and smoke outside of the fire compartment. Most applications will require an F-Rating, which is typically the fire resistance rating of the assembly. However, under 3.1.9.1(2), when

penetrating a firewall or under 3.2.1.2, a slab, an FT-Rating is required, which will limit the transmission of high temperatures through the assembly as well as the fire resistance rating.

Andrew Quattrociocchi, C.B.C.O., is the deputy chief building official for

the Township of Oro-Medonte, and a director with the Ontario Plumbing

Inspectors Association. He can be reached at quattroscorner@hotmail.com.