Tyco CC2 heads and draft stops

[Yikes]

In a Type V wood framed building, I had designed attic draft stops per code (CBC 708.4, 718.4) using 1/2" plywood.
The design-build sprinkler installer chose to use Tyco CC-2 sprinkler heads and mostly CPVC pipe.
The Tyco spec sheet has the following comment regarding draft stops:

"Concealed Space Area (CPVC Pipe) The area of the concealed space is not limited; however, for both Figure 2 and Figure 3, where CPVC pipe is being utilized, draft-curtains or full height walls must be provided at 1000 ft² (93 m²) areas. This draft curtain shall be at least 1/3 the depth of the concealed space or 8 in. (200 mm), whichever is greater, and be constructed using a material that will not allow heat to escape through or above the draft curtain."​

What does this mean? Even the best insulation allows some heat to escape. What level of performance should we be looking for in a draft curtain or draft stop? The contractor installed 1/2" plywood as per CBC 718.3.1, but we do not have a performance criteria for "not allow heat to escape".

https://tyco-fire.com/TD_TFP/TFP/TFP632_12_2018.pdf

 

[cda]

I would say the draft stop you speced meets it

It seems to meet the definition of draft stop,

And performs the same need as a draft stop

 

[tmurray]

In a Type V wood framed building, I had designed attic draft stops per code (CBC 708.4, 718.4) using 1/2" plywood.
The design-build sprinkler installer chose to use Tyco CC-2 sprinkler heads and mostly CPVC pipe.
The Tyco spec sheet has the following comment regarding draft stops:

"Concealed Space Area (CPVC Pipe) The area of the concealed space is not limited; however, for both Figure 2 and Figure 3, where CPVC pipe is being utilized, draft-curtains or full height walls must be provided at 1000 ft² (93 m²) areas. This draft curtain shall be at least 1/3 the depth of the concealed space or 8 in. (200 mm), whichever is greater, and be constructed using a material that will not allow heat to escape through or above the draft curtain."​

What does this mean? Even the best insulation allows some heat to escape. What level of performance should we be looking for in a draft curtain or draft stop? The contractor installed 1/2" plywood as per CBC 718.3.1, but we do not have a performance criteria for "not allow heat to escape".

https://tyco-fire.com/TD_TFP/TFP/TFP632_12_2018.pdf

I would interpret the current draft stops to meet this criteria.

I feel the intention is to ensure the sufficient build up of heat in the space to activate the head by not allowing it to dissipate quickly out of the space/building.

If the draft stop allowed NO heat to escape (impossible with our current technology level), the heads will activate eventually without a fire.

 

[classicT]

Is it a conditioned attic? Flat roof or pitched?

Draft curtains are utilized to minimize the spread of heat and smoke within a space, and typically will extend only a few feet below the ceiling.

Per the posted comment, it appears that the manufacturer is requiring draft curtains to prevent the dissipation of heat, which could result in a lack of activation of the sprinkler heads. For this to work, I'd imagine that it would have to be a flat roof within a conditioned attic. If unconditioned, heat will escape via the attic vents, and the system would presumably need to be a dry system.

constructed using a material that will not allow heat to escape through or above the draft curtain

I think that the intent here is to have the draft curtains provide a sealed connection to prevent the passage of smoke and heat.

 

[cda]

My bad

Draft Curtain

Same comment wood is good

Do you have 1000 sq ft of Concealed space ????

 

[cda]

"""not allow heat to escape through or above the draft curtain""

The plywood should do that, if installed correctly.

Plus either the sprinkler will activate or the building will burn down.

 

[classicT]

FYI, draft stopping is not required where sprinkled.

718.4.2 Groups R-1 and R-2
Draftstopping shall be provided in attics, mansards, overhangs or other concealed roof spaces of Group R-2 buildings with three or more dwelling units and in all Group R-1 buildings. Draftstopping shall be installed above, and in line with, sleeping unit and dwelling unit separation walls that do not extend to the underside of the roof sheathing above.

Exceptions:​

1. Where corridor walls provide a sleeping unit or dwelling unit separation, draftstopping shall only be required above one of the corridor walls.
2. Draftstopping is not required in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.
3. In occupancies in Group R-2 that do not exceed four stories above grade plane, the attic space shall be subdivided by draftstops into areas not exceeding 3,000 square feet (279 m2) or above every two dwelling units, whichever is smaller.
4. Draftstopping is not required in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.2, provided that automatic sprinklers are installed in the combustible concealed space where the draftstopping is being omitted.

718.4.3 Other Groups
Draftstopping shall be installed in attics and concealed roof spaces, such that any horizontal area does not exceed 3,000 square feet (279 m2).

Exception: Draftstopping is not required in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.​

 

[Yikes]

Ty J: I agree that the building code does not require the draftstopping; but the sprinkler manufacturer does require draft curtains every 1000SF when using CPVC pipe with this particular type of sprinkler head.

So we obtained building permit with a deferred approval on the sprinkler system, and then the design-build sprinkler company made material choices which had implications for our attic systems. In this case, the sprinkler contractor is on the hook for failing to notify the architect that their system would force a change the approved building design. Nevertheless, let this be a cautionary tale to architects and code officials: double-check the sprinkler head literature.

It just so happens that we have plywood shearwalls extending through the attic at all corridors and unit demising walls, which can effectively also function as draft curtains in this case, so if plywood works, then it dramatically reduces the number of required additional draft curtains.

FYI, the roof is low-slope ("flat") and the structure is open web gang nail trusses.

 

[cda]

Ty J: I agree that the building code does not require the draftstopping; but the sprinkler manufacturer does require draft curtains every 1000SF when using CPVC pipe with this particular type of sprinkler head.

So we obtained building permit with a deferred approval on the sprinkler system, and then the design-build sprinkler company made material choices which had implications for our attic systems. In this case, the sprinkler contractor is on the hook for failing to notify the architect that their system would force a change the approved building design. Nevertheless, let this be a cautionary tale to architects and code officials: double-check the sprinkler head literature.

It just so happens that we have plywood shearwalls extending through the attic at all corridors and unit demising walls, which can effectively also function as draft curtains in this case, so if plywood works, then it dramatically reduces the number of required additional draft curtains.

FYI, the roof is low-slope ("flat") and the structure is open web gang nail trusses.

When using in a Concealed Space.


These are not intended for large attics, unless it is a flat attic

 

[Yikes]

It is a "flat attic". The heel of the truss is about 18" tall. The peak of the truss is about 30" tall. Batt insulation takes up much of the concealed space.

 

[classicT]

It is a "flat attic". The heel of the truss is about 18" tall. The peak of the truss is about 30" tall. Batt insulation takes up much of the concealed space.

Out of curiosity, any idea why the design team did not elect to fill the entire attic space with insulation? Could completely avoid draftstopping and sprinklers.

Insulation is far cheaper by comparison.

 

[Yikes]

Out of curiosity, any idea why the design team did not elect to fill the entire attic space with insulation? Could completely avoid draftstopping and sprinklers.

Insulation is far cheaper by comparison.

The client preferred cross-ventilation in the attic. I guess they had a dew point / condensation issue on another project somewhere.

 

[TheCommish]

Is the an NFPA 13, 13D or other system?

My take, the issue is melting of the plastic piping. By providing draft stopping the heat area is contained, the heads in space activate in the concealed space and the fire/heat does not run through the concealed space..

 

[Yikes]

Full NFPA 13.
I heard back form the Tyco rep this morning. He confirmed that plywood is acceptable as a draft curtain.

Thanks for all your input.