Water Curtain vs. Rated Door on a Loading Dock?

5/31/2023

Water curtain using automatic sprinklers to avoid providing opening protectives - there's a lot of confusion on this.

Exception stated under Section 705.8.2 of 2021 International Building Code (OBC) states that Opening protectives are not required where the building is equipped through an automatic sprinkler system in accordance with Section 903.1.1 and the exterior openings are protected by a water curtain using automatic sprinkler systems approved for that use.

Can we use this exception and provide a water curtain using automatic sprinklers to avoid fire rated doors in the loading dock of a building?

Is there anything else that I need to be concerned about while designing these sprinklers for the water curtain?

Need more clarity here before recommending an approach. Thanks in advance.

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10 Comments

Glenn Berger

5/31/2023 08:16:51 am

You need to closely examine whether or not exterior opening protection is required based upon the relationship to adjacent buildings.

Can you comply with the provisions of a water curtain system in the project location?

I try to avoid water curtain systems, especially protecting exterior openings, due to the ITM requirements set forth in the applicable NFPA sections.

Pete H

5/31/2023 08:33:51 am

I'm just going to echo Glenn here, you're way better off using a fire rated exterior door than a water curtain for the exit.

I mostly stick to them just for vertical projections or unrated glass doors in multi tenant buildings, but the actual exterior door of a building is much better as a rated assembly imo.

Todd E Wyatt

5/31/2023 08:54:41 am

Q : Can we use this exception and provide a water curtain using automatic sprinklers to avoid fire rated doors in the loading dock of a building?
A : Yes ... IF the Exterior Wall (EW) is required to be fire-resistance rated (FRR) and the doors-in-question are located in the EW.

Exterior Walls (EW) are required to be fire-resistance rated (FRR) "in accordance with Table 601, based on the type of construction (and Occupancy Classification), and Table 705.5, based on the fire separation distance" per 2021 IBC 705.5 Fire-Resistance Ratings.

Depending on the type(s) of "fire rated doors in the loading dock" (vertical sliding doors vs horizontal swing/pivot doors), the design of the "water curtain" per the automatic sprinkler system (ASPS) would need to accommodate these conditions. While the initial intent for this water curtain "exception" may have been for fixed openings (e.g. windows), 705.8.2 references "Protected Openings" which could include fire doors.

In addition to the ASPS water curtain, the "Openings in exterior walls shall comply with Sections 705.8.1 through 705.8.6" which includes :

Allowable Area of Openings
Protected Openings
Unprotected Openings
Mixed Openings
Vertical Separation of Openings
Vertical Exposure

REFERENCES
2021 IBC
Chapter 7 Fire and Smoke Protection Features
Section 705 Exterior Walls
705.5 Fire-Resistance Ratings
Exterior walls shall be fire-resistance rated in accordance with Table 601, based on the type of construction, and Table 705.5, based on the fire separation distance. The required fire-resistance rating of exterior walls with a fire separation distance of greater than 10 feet (3048 mm) shall be rated for exposure to fire from the inside. The required fire-resistance rating of exterior walls with a fire separation distance of less than or equal to 10 feet (3048 mm) shall be rated for exposure to fire from both sides.
TABLE 705.5 FIRE-RESISTANCE RATING REQUIREMENTS FOR EXTERIOR WALLS BASED ON FIRE SEPARATION DISTANCE

705.8 Openings
Openings in exterior walls shall comply with Sections 705.8.1 through 705.8.6.
705.8.1 Allowable Area of Openings
705.8.2 Protected Openings
Where openings are required to be protected, opening protectives shall comply with Section 716.
Exception: Opening protectives are not required where the building is equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 and the exterior openings are protected by a water curtain using automatic sprinklers approved for that use.
705.8.3 Unprotected Openings
Where unprotected openings are permitted, windows and doors shall be constructed of any approved materials. Glazing shall conform to the requirements of Chapters 24 and 26.
705.8.4 Mixed Openings
705.8.5 Vertical Separation of Openings
705.8.6 Vertical Exposure

JP link

5/31/2023 09:03:46 am

I would avoid the water approach at an exterior door for a number of reasons especially due to exposure to the exterior/freezing. It also adds more cost overall than a rated door. To expand on what has been written above, first determine your fire separation distance. Next, based on FSD, decide if the wall even needs a rating. If it needs to be rated, use the FSD to determine the percentage of allowable unprotected openings.

Using IBC 2018, your key tables are 601, 602 and 705.8.

JP link

5/31/2023 09:05:23 am

Lastly, if the opening of the door and the other openings in the wall are less than the allowable %, than you do not need to rate the door.

SCHULMAN

5/31/2023 09:52:30 am

I'm on the side of the responders who are questioning the requirement ... in all my years of doing this I have yet to design or see a design where the wall and/or doors at the loading dock needs to be rated. Typically, the interior walls that separate the loading area from the rest of the building are rated. Would love to know why or more ...

MICHELE RIVAROLA

6/1/2023 01:32:59 am

It depends on whether fire rated separation is required or not. If it is required then a water curtain is not a substitute for a fire rated door. If a fire rated separation is not required and the loading dock is provided with a canopy then the sprinklers in the canopy will provide protection and no water curtain is necessary. If no fire separation is required and the loading dock is not provided with a canopy and trucks are parked at the loading dock unmanned then a water curtain is probably a viable system of detection but unlikely to provide adequate protection.

Anthony

6/1/2023 08:35:18 am

My 2 cents: with the exception of some very special sprinklers, sprinklers do not and should not be used for rating structure. I believe it is not good practice to replace a rated architectural/structural component with a 'water curtain'. The design intent often gets lost in subsequent years when it comes time to renovate under the best of circumstances like at a university where documents are better organized. At a commercial or industrial setting where a structure can changes hands 'relatively' quickly this problem is exasperated. Add to that the reliability of a door compared to a sprinkler system and your choice should be clear.

Also sprinklers near a loading dock are asking to get clipped by a forklift or truck. We've all seen a side wall sprinkler under the garage door that gets sheard off by a forklift or truck, etc.

Rob Evans

9/17/2025 12:46:09 am

I strongly disagree with that opinion. I’ve installed rolling and sliding fire doors for 30 years and the dependability on the door closing is very low. I’ve heard in our industry that over 90% of fire doors installed in the field have something wrong with them be it installed wrong , corrective measures not taken or plain damage as to why.
I have my designs used and sold everyday and would trust a water fire door over a traditional fire door 10 times out of 10. Additionally, it allows the architect to spec a more esthetic or application functional door on the rated wall.

Alex

6/2/2023 04:27:52 am

Late to the party here but want to echo what others have said.

I wouldn’t be quick to use sprinklers to achieve your fire rating. I only use them for atriums. Have the code consultant review your property separation and confirm that a rating is required in the first place.

Water Curtain vs. Rated Door on a Loading Dock?

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