Proper Materials for an Attic Draft Curtain?

5/9/2022

Can anyone point me in the right direction for codes pertaining to the construction of a draft curtain?

My client will be installing them as part of an attic design, where draft curtains are required per the sprinkler listing.

The sprinkler data sheet covers the depth requirement of the draft curtain. From browsing some websites I can gather they can be constructed of fire-resistant fiberglass woven textiles, glass (smoke baffles), or even panels of sheet metal.

Does NFPA or the IBC define how they are to be constructed?

My client will most likely use sheet metal. I'm curious if there is a gauge requirement for the metal. I may be overthinking it, but I like to see the code defining the curtain requirement, to avoid the contractor putting the wrong materials in place. I appreciate any help that anyone can provide. Thank you.

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8 Comments

Pete H

5/9/2022 06:45:27 am

From NFPA 13 (2016):

8.15.4.2 - Draft Stops - Draft Stops shall meet all of the following criteria:
1) Draft stops shall be located immediately adjacent to the opening.
2) The draft stops shall be at least 18 in. deep.
3) The draft stops shall be of noncombustible or limited-combustible material that will stay in place before and during sprinkler operation.

Jesse

5/9/2022 08:17:26 am

Good question. I'd refer to NFPA 204 where it talks about draft curtains, though I don't recall it specifying a minimum gauge for sheet metal.

The purpose is to prevent lateral spread of the mushrooming convection column so as long as its non-combustible material and meets the elements of 13 spelled out about as well as 204 I think you're good. Maybe consult your AHJ.

Todd E Wyatt

5/9/2022 08:17:31 am

Per 2021 IBC :

Section 718 Concealed Spaces
718.1 General
Fireblocking and draftstopping shall be installed in combustible concealed locations in accordance with this section. Fireblocking shall comply with Section 718.2. Draftstopping in floor/ceiling spaces and attic spaces shall comply with Sections 718.3 and 718.4, respectively.

718.3 Draftstopping in Floors
Draftstopping shall be installed to subdivide floor/ceiling assemblies where required by Section 708.4.2. In other than Group R occupancies, draftstopping shall be installed to subdivide combustible floor/ceiling assemblies so that horizontal floor areas do not exceed 1,000 square feet (93 m2).

Exception: Buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.

718.3.1 Draftstopping Materials
Draftstopping materials shall be not less than 1/2-inch (12.7 mm) gypsum board, 3/8-inch (9.5 mm) wood structural panel, 3/8-inch (9.5 mm) particleboard, 1-inch (25-mm) nominal lumber, cement fiberboard, batts or blankets of mineral wool or glass fiber, or other approved materials adequately supported. The integrity of draftstops shall be maintained.

718.4 Draftstopping in Attics
Draftstopping shall be installed to subdivide attic spaces where required by Section 708.4.2. In other than Group R, draftstopping shall be installed to subdivide combustible attic spaces and combustible concealed roof spaces such that any horizontal area does not exceed 3,000 square feet (279 m2). Ventilation of concealed roof spaces shall be maintained in accordance with Section 1202.2.1.

Exception: Buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.

718.4.1 Draftstopping Materials
Materials utilized for draftstopping of attic spaces shall comply with Section 718.3.1.

718.4.1.1 Openings
Openings in the partitions shall be protected by self-closing doors with automatic latches constructed as required for the partitions.

5/9/2022 08:21:03 am

The NFPA defines a "Draft Curtain" as a “Fixed or Automatically deployable noncombustible barrier that protrudes downward from the ceiling to channel, contain or prevent the migration of smoke.”

Draft Curtains, or “smoke baffles,” have traditionally been used around stairways, which must be used for Exit Access in the event of an evacuation. These systems delay smoke from migrating vertically via the structure’s stairs. They are used in conjunction with sprinkler systems to direct water flow.

See https://firecurtaintechnologies.com/blog/nfpa-draft-curtain-requirements/

Mohamed Hassan, CFPS, CFI I, PMP

5/9/2022 08:28:55 am

The guidelines for selecting the material of draft curtains are provided at NFPA 204.
- Per NFPA 204 Section A.3.3.9, the draft curtain could be a solid fixed construction or deployable barrier.
- Per NFPA 204 Section A. 7.2, the material suitable for use as draft curtain can include steel sheeting, cementous panels, and gypsum board or any other materials that meet performance criteria in NFPA 204 Section 7.2.
- It could be also from lightweight, non-combustible construction, fixed fabric curtains whenever the compliance with NFPA 13 & 204 is achieved.

Alex

5/9/2022 08:43:22 am

Hi,

I'm late to the game this morning! Mohamed has already sited the code sections I was going after.

Thanks,
Alex

Eric R

5/9/2022 09:41:14 am

When we install interstitial sprinklers, our jurisdiction uses the IBC so what Todd posted is what we are used to.

718.3.1 Draftstopping Materials
Draftstopping materials shall be not less than 1/2-inch (12.7 mm) gypsum board, 3/8-inch (9.5 mm) wood structural panel, 3/8-inch (9.5 mm) particleboard, 1-inch (25-mm) nominal lumber, cement fiberboard, batts or blankets of mineral wool or glass fiber, or other approved materials adequately supported. The integrity of draftstops shall be maintained.

There is a pretty big difference with this description and the requirement from NFPA 204 to us a non-combustible material. Gypsum board is by far the most common material we see used, but we occasionally see draftstops made from particle board which doesn't sound like it would jive if NFPA 1 is used as the governing code instead of the IBC.

Patrick Drumm

5/31/2022 07:24:40 am

Apologies for the delay, but thank you everyone for submitting there comments. They were very helpful all around to confirm the acceptable materials.

Proper Materials for an Attic Draft Curtain?

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