Does Draftstop Require Firestopping?

11/11/2022

We are a sprinkler contractor running into a new situation for an apartment building. The apartment is designed under NFPA 13R.

We have an inspector requesting that we firestop a draft stop from the corridor into an apartment.

Can you point us in the right direction whether this is required?

Thanks in advance for your help.

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5 Comments

Adam

11/11/2022 08:25:54 am

In Ontario Canada, the concealed open space caused by open web joists, or by roof trusses, is required to be split up into areas of certain square footages, and this 'draft stop' would be referred to as a fire block, which is of fairly minimal construction, and generally doesn't have a Fire Resistance Rating associated with it.

When it comes to penetrations, though, it does require fire stopping. Oddly enough though, ducts do not require fire dampers.

A bead of Hilti or 3M fire stop sealant does the trick.

Todd E Wyatt

11/11/2022 09:15:23 am

SUMMARY
If the floor/ceiling assembly is an approved 1-Hr fire-resistance rated (FRR) Horizontal Assembly (HA) separating the dwelling units and meeting the Type of Construction FRR requirements for the Floor Construction, firestopping the draftstop inside this FRR HA is NOT required.
Draftstops are not required to have a fire-resistance rated (FRR) but instead are required to “restrict the movement of air”. Penetrations in draftstops would only be required to “restrict the movement of air”.

EXPLANATION
Draftstopping is used to restrict the movement of air (e.g. smoke) in concealed, combustible spaces.
2021 IBC
DRAFTSTOP. A material, device or construction installed to restrict the movement of air within open spaces of concealed areas of building components such as crawl spaces, floor/ceiling assemblies, roof/ceiling assemblies and attics.

Fireblocking is used to control the migration of flame in concealed, combustible spaces.
2021 IBC
FIREBLOCKING. Building materials, or materials approved for use as fireblocking, installed to resist the free passage of flame to other areas of the building through concealed spaces.

Firestopping is used to seal around openings (through penetrations & membrane penetrations) and at joints in a fire-resistance-rated (FRR) wall or floor assembly. Firestops maintain the FRR of a wall or floor assembly intended to impede the spread of fire and smoke.
2021 IBC
MEMBRANE-PENETRATION FIRESTOP. A material, device or construction installed to resist for a prescribed time period the passage of flame and heat through openings in a protective membrane in order to accommodate cables, cable trays, conduit, tubing, pipes or similar items.
MEMBRANE-PENETRATION FIRESTOP SYSTEM. An assemblage consisting of a fire-resistance-rated floor-ceiling, roof-ceiling or wall assembly, one or more penetrating items installed into or passing through the breach in one side of the assembly and the materials or devices, or both, installed to resist the spread of fire into the assembly for a prescribed period of time.

Per 2021 IBC, a Dwelling Unit (“A single unit providing complete, independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking and sanitation.”) and/or a Sleeping Unit (“A single unit that provides rooms or spaces for one or more persons, includes permanent provisions for sleeping and can include provisions for living, eating and either sanitation or kitchen facilities but not both. Such rooms and spaces that are also part of a dwelling unit are not sleeping units.”) in a Group R Residential occupancy are required to be protected by Fire Partitions (FP) with a fire-resistance rating (FRR) of 1-Hour or 0.5-Hours in buildings of Types IIB, IIIB and VB that are also protected by an automatic sprinkler system (ASPS). Fire Partitions (FP) unlike Fire Barriers (FB) are not required to extend to the underside of the floor construction but are permitted to terminate at a floor/ceiling assembly having the same FRR as the FP. FPs are required to be supported by construction having the same FRR as the FP except in buildings of Types IIB, IIIB and VB that are separating dwelling units and sleeping units from Group R-1 and R-2 occupancies.

In the example provided, the dwelling unit’s FP terminates at the underside of a floor/ceiling assembly. The unknown is the FRR of the associated floor/ceiling assembly … let’s assume it is also 1-Hour.

The Type of Construction (TC) of the building (see IBC Table 601) also determines the required FRR of the Primary Components including the Floor Construction (e.g. Horizontal Assembly – HA). The TC is determined to comply with the building’s Occupancy Classification(s) (OC) which relates to the allowables including maximum building area (by story), maximum number of stories, and maximum building height. Let’s assume the Floor Construction is 1-Hour. This would mean the building is either Type IIIA (exterior walls noncombustible & interior building elements are any material permitted) or Type VA.

2021 IBC 708.4.2 Fireblocks and Draftstops in Combustible Construction includes the prescriptive requirements for fireblocks & draftstops where “where fire partitions (that) do not extend to the underside of the floor or roof sheathing, deck or slab above” in combustible construction. 708.4.2 includes (5) exceptions that should be reviewed to see if they are applicable.

Lastly, NFPA 13R is permitted in Group R occupancies per 2021 IBC 903.2.2 where the building meets all the following conditions :
1. Four stories or fewer above grade plane.
2. The floor level of the highest story is 30 feet (9144 mm) or less above the lowest level of fire department vehicle access.
3. The floor level of the lowest story is 30 feet (9144 mm) or less below the lowest level of fire department vehicle access.

Eric R

11/11/2022 09:54:49 am

To add to this, you'll want to make sure that the construction of the corridor FP membrane meets the requirements of 708.4. In the drawing provided, it looks like the apartment side of the wall conforms with a standard UL FRR sketch, but if the corridor ceiling is not constructed in the same arrangement as the corridor wall it is possible that the membrane in question is not actually a draftstop, but instead is a continuation of the corridor's fire partition membrane.

Also, the code language for draftstops includes a line requiring the integrity of the draftstop to be maintained. So even if it doesn't require a rated firecaulk, the penetration should probably still be stuffed with some insulation.

Either way, a quick run of firecaulk seems like a simple enough add compared to a potential argument with the AHJ slowing down the project.

Cesar Flores

11/11/2022 10:08:40 am

If it's a 13r per my knowledge you consider the concealed space. If it's design 13r.

sean

11/12/2022 07:25:36 am

this is coming from chapter 7 of the IBC. But in a NFPA 13R system if the draftstopping is ommited then sprinkler protection is required in the concealed space.

Does Draftstop Require Firestopping?

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