Combustible pipes in noncombustible buildings

By: Andrew Quattrociocchi

When do FSR and SDC come into play?

It’s that time again. I am back at it with another informative Quattro’s Corner. Combustible pipes in noncombustible buildings is a subject I frequently get questions on; more specifically, when do the flame spread rating (FSR) of not more than 25 and smoke development classification (SDC) of not more than 50 come into play?

To help me break all of this down, I have teamed up with Kevin Yong-Ping, regional engineer for plastic pipe manufacturer IPEX.

Let’s get to some basics.

The Ontario Building Code and National Building Code of Canada Division B Part 3 specifically 3.1.5. Noncombustible construction set out the requirements for a building or part of a building that is required to be of noncombustible construction and states: Noncombustible Material

(1) Except as permitted by Sentences (2) to (4) and Articles to to NBC), and, a building or part of a building required to be of noncombustible construction, shall be constructed with noncombustible materials. Combustible piping materials further explains the requirements that must be met in order for combustible pipe to be installed. Combustible Piping Materials 

(1) Except as permitted by Sentences (2) and (3) and by Clause and Article (Ontario only)., combustible piping and tubing and associated adhesives are permitted to be used in a building required to be of noncombustible construction provided that, except when concealed in a wall or concrete floor slab, they,

(a) have a flame-spread rating not more than 25, and

(b) if used in a building described in Subsection 3.2.6., have a smoke developed classification not more than 50.

(2) Combustible sprinkler piping is permitted to be used within a sprinklered floor area in a building required to be of noncombustible construction.

(3) Polypropylene pipes and fittings are permitted to be used for drain, waste and vent piping for the conveyance of highly corrosive materials and for piping used to distribute distilled or dialyzed water in laboratory and hospital facilities in a building required to be of noncombustible construction, provided,

(a) the building is sprinklered

(b) the piping is not located in a vertical shaft, and

(c) piping that penetrates a fire separation is sealed at the penetration by a fire stop that has an FT rating not less than the fire-resistance rating of the fire separation when subjected to the fire test method in CAN/ULC-S115, “Fire Tests of Firestop Systems”, with a pressure differential of 50 Pa between the exposed and unexposed sides, with the higher pressure on the exposed side.

Sentence 1 (b) to me is one of the most important hints when trying to figure out part 1 of our question. Combustible piping must meet the FSR of 25 and SDC of 50 when used in High Building. This is a heads up for some larger municipalities in Ontario and across Canada, while some smaller municipalities can chill out.

The only other time combustible piping is required to meet both the 25 and 50 is when the piping is installed in a plenum space as per which states:

A concealed space used as a plenum within a floor assembly or within a roof assembly need not conform to sentence and Article provided all materials within the concealed space have a FSR of not more than 25 and a SDC not more than 50.

It is time to stop thinking that all residential and ICI small and large buildings require a combustible pipe to meet the 25 and 50 requirements. Most inspectors just assume if it’s noncombustible construction it needs both. Not only is that incorrect, it is also costing the plumber and owners of these buildings more unnecessary money.

That’s it for this edition of Quattro’s Corner. Agent Q signing out.


Questions to ask

The next time you’re working at a site that’s noncombustible construction, ask yourself these questions:

  1. Is the pipe material combustible?
  2. Am I in a high building with combustible pipe?
  3. Do I see combustible pipes in a plenum?

If you answer no to numbers 2 and 3 then the

combustible pipe only needs to meet the FSR of 25.

It’s that simple.