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secondary suite: is the ceiling of the furnace room required to be drywalled when sprinkler system is installed

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sunyaer

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Location
Toronto
In Ontario, for a house with secondary suite, with respect to the ceiling fire protection of the furnace room where sprinkler system is installed, I found there is a lot of confusion about whether or not the ceiling of the furnace room is required to be drywalled:

Here is a fire code brochure from the City of Barrie: https://www.barrie.ca/sites/default/files/2022-07/FireCode-Brochure.pdf

"While sprinkler systems are not mandatory, their installation may lower the requirements for fire containment in a room with a fuel fired appliance. The installation only exempts the ceiling above the appliance(s) from fire rating..."

Question: is it clear that the ceiling of the furnace room is required to be drywalled?
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Here is a guide from the City of Collingwood: https://www.collingwood.ca/sites/de...nts/b408pgresaccessoryapartment20210915_2.pdf

On page 18, there is a sketch showing the ceiling of the furnace room is not drywalled. and on page 25:

" Notes to Table B: 1. Horizontal fire separations are waived in a service room where the service room is sprinklered (discussion on placement & number of heads required will be determined on site) and the installation satisfies the following: ..."

According to the sketch and notes of the guide from Collingwood, the ceiling of the furnace room where there is sprinkler system is not required to be drywalled.
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The following is from Ontario Building Code Division B – Part 11 Table 11.5.1.1.C.

"C149 9.10.9.10.(1)
Ceiling fire separation need not have a fire-resistance rating where sprinklering,
subject to C.A. C27, of fire compartments on both sides of vertical fire separation is
provided and where such fire separation is not required to exceed 1 h."

Question: Is the ceiling of the furnace room required to be drywalled when the Ceiling fire separation need not have a fire-resistance rating?
 
So, just to clarify, this would just apply to renovations of an existing building where a secondary suite is created. This would not apply to new construction that will incorporate a secondary suite.

From my reading, the rating is waived, but the separation is still required (commonly called a "smoke seal"). This is similar to 9.10.10.3, which allows the same thing. basically, the only thing that needs to be accomplished is the control of smoke movement between suites.
 
I agree. the assembly needs to be constructed as a fire separation, but the assembly does not need a fire resistance rating. This means it needs to be constructed as a barrier to smoke and gasses and other products of combustion, but will not have a rating in time.
 
tmurray said:
So, just to clarify, this would just apply to renovations of an existing building where a secondary suite is created. This would not apply to new construction that will incorporate a secondary suite.

From my reading, the rating is waived, but the separation is still required (commonly called a "smoke seal"). This is similar to 9.10.10.3, which allows the same thing. basically, the only thing that needs to be accomplished is the control of smoke movement between suites.
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Yes, renovations of an existing building.

From what I have found from searching the public information from a few municipal cities/towns in Ontario, like the guide from Collingwood, the ceiling of the furnace room where sprinkler system is installed is not required to be drywalled, though Collingwood requires 6" mineral wool produced from rock slag be filled in spaces between floor joists, and drywall on vertical separations of the furnace room is required to go up to the underside of sub-floor.

What would the requirement of the ceiling not being drywalled in the furnace room be based on?
 
sunyaer said:
Yes, renovations of an existing building.

From what I have found from searching the public information from a few municipal cities/towns in Ontario, like the guide from Collingwood, the ceiling of the furnace room where sprinkler system is installed is not required to be drywalled, though Collingwood requires 6" mineral wool produced from rock slag be filled in spaces between floor joists, and drywall on vertical separations of the furnace room is required to go up to the underside of sub-floor.

What would the requirement of the ceiling not being drywalled in the furnace room be based on?
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Running the sheetrock to the underside of sub-floor would also be acceptable to create smoke control, provided the joint is sealed somehow.

I'm not sure of the exact application here, but typically this would be driven by separation of residential suites is under 9.10.9.14. an exception to the rating requirement would help as there are usually a ton of ceiling penetrations and it would be a challenge and cost prohibitive to firestop/damper.

Alternatively, if the furnace room is not located in a suite, 9.10.10.3 would be the section driving this, but I feel 9.10.9.14 is more likely as we are talking about a renovation and are likely looking at adding a dwelling unit to an existing building.
 
Looking at OBC (which I am not familiar with) the language seems pretty clear: the *suites* are separated by 45 min assemblies. So the way I would read it, in a situation with a secondary suite, the furnace would be in one suite (ie: the main dwelling unit) which would not require a fire-rated assembly between floors, but if the furnace supplied heat to the secondary suite, the feed and return ducts would require fire dampers at the point of penetration.

Obviously, if the floor of the suite containing the furnace also demised the two suites, then this would have to be an F/R assembly. Dampers would still apply if the furnace heated both units.
 
Inspector Gadget said:
Looking at OBC (which I am not familiar with) the language seems pretty clear: the *suites* are separated by 45 min assemblies. So the way I would read it, in a situation with a secondary suite, the furnace would be in one suite (ie: the main dwelling unit) which would not require a fire-rated assembly between floors, but if the furnace supplied heat to the secondary suite, the feed and return ducts would require fire dampers at the point of penetration.

Obviously, if the floor of the suite containing the furnace also demised the two suites, then this would have to be an F/R assembly. Dampers would still apply if the furnace heated both units.
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I think the main question here is whether or not fire separation with 0 hours fire rating is required, and without being drywalled underside of the ceiling, would the floor assembly be considered a fire separation?
 
sunyaer said:
I think the main question here is whether or not fire separation with 0 hours fire rating is required, and without being drywalled underside of the ceiling, would the floor assembly be considered a fire separation?
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It either has to be a rated separation or it doesn't, under the OBC - as I read it.
 
In California there is a requirement for sound control which incorporates drywall...how about Canada?
 
ICE said:
In California there is a requirement for sound control which incorporates drywall...how about Canada?
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Yes. NBC 9.11 has requirements for sound transmission class in assemblies demising secondary suites from the main dwelling.
(also applies to other building combinations with residential suites.)
 
Inspector Gadget said:
Yes. NBC 9.11 has requirements for sound transmission class in assemblies demising secondary suites from the main dwelling.
(also applies to other building combinations with residential suites.)
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Coming back to the original question: In a house with secondary unit, is sprinkled furnace room without ceiling drywall compliant with the code?
 
sunyaer said:
Coming back to the original question: In a house with secondary unit, is sprinkled furnace room without ceiling drywall compliant with the code?
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The OBC (9.10.9.14)(5) states " The fire-resistance rating of the fire separation required in Sentence (4) is permitted to be waived where the house is sprinklered."

That means you must still have a zero-rated fire separation. If there is no ceiling drywall, the designer has to indicate how the smoke-tight barrier is provided.
 
Inspector Gadget said:
The OBC (9.10.9.14)(5) states " The fire-resistance rating of the fire separation required in Sentence (4) is permitted to be waived where the house is sprinklered."

That means you must still have a zero-rated fire separation. If there is no ceiling drywall, the designer has to indicate how the smoke-tight barrier is provided.
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I used "smoke-tight barrier" to search in google, and it looks like without ceiling drywall, the floor can achieve a smoke-tight barrier.
 
sunyaer said:
I used "smoke-tight barrier" to search in google, and it looks like without ceiling drywall, the floor can achieve a smoke-tight barrier.
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Nyet.

9.10.8.10. Application to Houses
1) Table 9.10.8.1. does not apply to
a) a dwelling unit that has no other dwelling unit above or below it,​
b) houses with a secondary suite, where the floor framing is protected on the underside by a continuous smoke-tight barrier of not less than 12.7 mm thick gypsum board, or​
c) a dwelling unit that is not above or below another major occupancy.​
 
Also 9.10.9.14 (NBC)

4) Walls and floor-ceiling framing in a house with a secondary suite that separate
dwelling units from each other or dwelling units from ancillary spaces and common
spaces need not comply with Sentence (1), where the walls and floor-ceiling framing
are protected by a continuous smoke-tight barrier of not less than 12.7 mm thick
gypsum board installed on
a) both sides of walls, and
b) the underside of floor-ceiling framing.
(See Sentence 9.10.9.3.(2) for closures.)
 
Inspector Gadget said:
Nyet.

9.10.8.10. Application to Houses
1) Table 9.10.8.1. does not apply to
a) a dwelling unit that has no other dwelling unit above or below it,​
b) houses with a secondary suite, where the floor framing is protected on the underside by a continuous smoke-tight barrier of not less than 12.7 mm thick gypsum board, or​
c) a dwelling unit that is not above or below another major occupancy.​
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In your opinion, without ceiling drywall, can a floor achieve a smoke-tight barrier? What about in a house with a secondary unit, a furnace room ceiling with 6" mineral wool produced from rock slag filled in spaces between floor joists, and drywall on vertical separations of the furnace room goes up to the underside of sub-floor?
 
sunyaer said:
In your opinion, without ceiling drywall, can a floor achieve a smoke-tight barrier? What about in a house with a secondary unit, a furnace room ceiling with 6" mineral wool produced from rock slag filled in spaces between floor joists, and drywall on vertical separations of the furnace room goes up to the underside of sub-floor?
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Looking at NBC, the language seems clear - the smoke tight barrier must include drywall or something similar. See also 9.10.19.4

(Stated again with the proviso that the separation is required between suites: if the floor/ceiling assembly is contained within one suite, then no F/S is required - 9.10.9.4(2)
 
I think the main issue with using the sub-flooring as the barrier is joint treatment. Sheetrock has to be fire taped (just roughly finished with crackfilling compound and joint tape) to be considered smoke tight. I would imagine something similar would be required for the floor sheathing. Also of interest would be the continuity of the barrier.
 
Just Wondering
If this is a warm air furnace, and the unit was installed in an unfinished basement, then I doubt anyone would insist the entire ceiling be finished with drywall.

So, now we are talking about an equipment closet with a small amount of drywall, so I wonder why the builder is reluctant to "rock the closet?
Does the installed equipment make this space really difficult to drywall and that is why? It can't be drywalled before the installation?
Do they see it as leaving the space accessible for future maintenance?
If this is a 13D doesn't the PVC pipe need to be protected?

Why the conversation for such a low-cost situation?

PS if these are I Joist, and the heat source in a small space, that could be point of ignition, I would think the added protection of drywall would be prudent, even with the plenum and duct penetrations that would complicate or even compromise the drywall's effectiveness

IMHO
 
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