Thread: Fire Sprinkler in Attic of Townhouse

The two photos were taken from a 10-year townhouse showing the sprinkler head and the standpipes in attic. This is a roll-house built on concrete garage podium with concrete slab on second floor. Together with timber trusses on roof and wood siding on exterior walls.

It is rare in BC, any comment? Is there any reason made the builder install the fire sprinkler system in attic?

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Originally Posted by Daniel Leung

Is there any reason made the builder install the fire sprinkler system in attic?

To fall within the protection allowances for "fully sprinklered" the code states "all areas", and the attic is an "area".

There are AHJ which interpret that both ways, yes - sprinkler it, and no - not needed.

Make sure there is a heater in the attic area with a thermostat set for around 40 degrees F. Generally the heater will be a small electric type. All fire sprinkler systems have to protected from freeze damage unless the fire sprinkler system is a dry pipe type, which is not common in townhouses.

Don Merritt
Germantown, Tennessee

Originally Posted by Donald Merritt

All fire sprinkler systems have to protected from freeze damage

Not just the fire sprinkler systems, *ALL* water piping systems installed outside the thermal envelope of the building have to be protected by freezing. Water supply piping *and* DWV piping. That is something which I continuously point out as being required above the freeze line, which is basically running along I-10, which runs across the northern edge of Florida over across to Texas and up to California - above that and freeze protection *is a requirement* for *all* water piping ... in the attic, in the crawlspace, in the exterior wall outside the insulation, *all* ...

Not sure what codes Canada is using, but a NFPA 13 sprinkler system requires sprinklers in an attic. They are protected from freezing by being a dry system charged with air. When a sprinkler head activates it releases the air which then releases a valve which then allows the water to the head. The system is kept charged with air with a compressor for minor fluctuations due to temperature changes.

Thanks Fred, I'm not sure the Canadian fire code too. You bring up the NFPA 13 gave me the possible answers from this article: The Sprinkler The Trade-Off Trade-Up Concept

"A reduction in attic draft stopping is permitted only when sprinklers are provided in the attic."
" Unless sprinklers are provided in the attic, the required fire stopping must be installed."
"By providing sprinklers in the attics and concealed spaces the 13R provides similar protection to the NFPA 13 system."
" Reductions in the required attic draftstopping would only be permitted where the attic is sprinklered."

Just wondering - did you find a compressor at the sprinkler main riser. That would indicate a dry
system. Something like this:

Originally Posted by Gary Anglin

Just wondering - did you find a compressor at the sprinkler main riser.

Yes, there is a air compressor in the fire sprinkler room.

Hi there, Daniel (et al) &

'Rare', all right, to be sure &

I have NEVER, ever seen such 'up here' (West Coast of Canada) !

Been around Strata properties for some 20 years & that's a first ! Yes of course it would have to be tempered /protected from freezing - unless 'dry'...


CHEERS

Another method of preventing sprinkler pipes from freezing is by installing glycol loops (a check valve is installed at some point in the heated space, near the point where the pipe enters the non-heated space and an antifreeze solution is placed in the pipes to keep them from freezing. If the system trips (a head opens) the glycol is discharged followed by untreated 'fresh' water - the flowing water will not freeze (especially if the area is involved in a fire).

If you ever find yourself in a building with a sprinkler system and want to know if a dry system is protecting the the non-heated portions, the valve body (located in the 'riser' room) will have the word 'dry' stamped or forged right on it. Also, the pressure gauge above the dry valve will show a lower reading than the pressure gauge above the valve (i.e. if city water pressure is 60-70 psi the system air pressure may be set around 40 psi). Wet systems, on the other hand, will have more pressure above the valve (i.e. city water pressure, typ b/t 60-70 psi, and system water pressure may be as high as 125 psi).

Sometimes the dry system is fed off a wet system (this is called a tail-end dry system). In this case the dry valve and trim is not located in the main 'riser' room - but typically next to the point where the pipes penetrate into the unheated space.

The most important item to verify is that the valves in the riser room are wide open. . . if not, then the sprinkler system is 'impaired' and will not function as required.

I know this was a lengthy post - but this is one of my areas of knowledge. If you ever have a sprinkler system or fire safety question just send me an email.

Originally Posted by Ian Currie

I know this was a lengthy post - but this is one of my areas of knowledge. If you ever have a sprinkler system or fire safety question just send me an email.

Thank you, Ian. It is wonderful to have so many experts here!

Hello all. This is neither a dry system or an anti-freeze system. These are dry barrel upright sprinklers fed by a wet system.

A "dry sprinkler" is a type of sprinkler head assembly designed for use in applications where the sprinklers and/or a portion of the connecting piping may be exposed to freezing temperatures. The basic function of the "dry sprinkler" is to prevent water or condensation from entering the dry pipe portion or "barrel" of the assembly before sprinkler operation. In a wet sprinkler system, they are typically installed in spaces subject to freezing and are supplied through various lengths of dry barrel extensions typically supplied by way of a "T" connection to wet piping in an adjacent heated area. In dry and pre-action sprinkler systems, they are installed where pendent sprinklers are required to protect areas supplied by dry sprinkler piping located in unheated portions of buildings.

Unlike a standard sprinkler head, which has a single point of mechanical operation, the "dry sprinkler" has two points of mechanical operation. The first point of operation is the heat-sensing element located in the sprinkler head which activates when exposed to the heat from a fire. The second point of operation is followed by the immediate release of an internal plug and O-ring seal located at the opposite end of the dry sprinkler assembly allowing water to enter the barrel and flow to and out of the sprinkler head.

Hope this helps clear up any confusion.
Thomas (a sprinklerman)

I don't have the NFPA readily available, but I believe that a 13R system doesn't require sprinklers in the attic. A 13R system is allowed is most low-rise residential buildings (up to 4 stories).

If there are sprinklers in the attic, it was likely designed as an NFPA 13 system, and not a 13R. They might have needed a 13 system to get the height or area increase allowed by IBC.