Very Large Floor/Ceiling Space Still Concealed?

9/26/2022

Hi all, I need help on this one:

There is a floor space in between the roof and the top story of a building. It's non-combustible construction.

The floor space in-between the roof and top story is 13-ft (4 m) high with limited access, about 64,000 sqft (6,000 m²) in floor area, no occupancy or storage intended, only pipes and ducts will be in this space and the equipment will be at roof level.

The architects refer to this as a concealed space.

1. Can this be considered a concealed space?

2. Are there any limitations for concealed space in terms of size?

3. Does this space requires sprinklers?

Any suggestions will be highly appreciated.

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14 Comments

Glenn Berger

9/26/2022 08:14:58 am

Your question said "limited-access," "floor space" and "no occupancy or storage intended." These are buzz words trying to skirt code requirements. My gut reaction is that during the life of this facility, this space will be used and therefore sprinklers should be installed at this time.

Jesse

9/26/2022 08:19:11 am

I missed the "limited access" part. Access changes this for me and I agree with Glenn's assessment. I think it should be protected.

Alex

9/26/2022 09:13:17 am

Glenn hit the big points here. I would be nervous based solely on the language used in the question here. I would confirm it is truly meant to be a congealed space before omitting sprinklers.

Simon

9/28/2022 11:12:28 am

Hi Glenn,

Thanks for your comment, let me explain why I used these words:

1. Limited access: There will be 2'x2' access hatches not from same floor level or from level below. These access hatches are going to be on the roof above. This makes storage to be very difficult, almost impossible.

2. Floor space: The floor is not a suspended ceiling, it is a non-combustible floor. This space is designed to have "conical-shape" skylights from the roof above down to the ceiling of the floor below; and also it will be used to run all ducts, pipes and conduits. All mechanical equipment will be at roof level.

Does it require sprinklers?

Can be Fire Alarm devices used in lieu of sprinklers?

Thanks for your help.

Greg

9/26/2022 08:16:00 am

I have seen this type of space in differing configurations; solid floor with drains, grated suspended floor over ceiling tile, and truss supported floor decking.

This space is a bit of a platypus. Are there any mechanicals in the space that are in addition to the pipes mentioned? Is this space actually a mechanical room and based on your floor configuration, sprinklers may be appropriate?

In any of these spaces, while storage is 'not allowed' the temptation to store items (such as pipe insulation in boxes left over from the construction) is very very real. Managing this space to zero storage for the life of the facility is very unlikely.

If it is decided that sprinklers are not possible and not required, consider adding a standpipe hose connection in the hallway wall near the door that leads to this space.

I'm curious to review the chat to understand what experiences others have had with these spaces; both new and retrofit / remodels.

Greg

9/26/2022 08:29:56 am

I did forget to mention, on the chance it is a grated suspended floor over ceiling tiles and the space below the tiles is an assembly occupancy or any populated occupancy .... and assuming you do install sprinklers, what is the result of a fire even where one sprinkler actuates , and subsequent alarm (up to 60 seconds) , in regards to the safety of people below from saturated ceiling tiles.

If this is the situation, over suspended tiles, I would think heat detectors in lieu of. But possibly others have some thoughts about this possibility...

Jesse

9/26/2022 08:16:54 am

Well, it is a concealed space by definition. However, I don't see this a combustible concealed space unless building equipment in that space is combustible. Its not different from a non-combustible buildout in a large shell building where we may protect the office occupancy below but not the area above.

Note that you may have some triggers to protect it such as if other areas below are open to deck or they intend to have any miscellaneous storage there. Additionally, I've seen AHJs require protection in the event a tenant stores something there.

Jesse

9/26/2022 08:17:58 am

I think I missed the "limited access" part. How limited is the "limited" access??

Simon

9/28/2022 10:49:54 am

There are a couple of 2x2 hatches accessible from the roof above, my guess is that they have these for service. I don't think there is any possibility they use this space for storage. From the roof to the floor space is 13 ft high. No other access points from the floor below.

Wiley Wilson link

9/26/2022 08:25:48 am

NFPA 13 - 2013 Chapter 8/8.15 Special Situations
8.15.1.2.2-Concealed spaces of noncombustible and limited combustible construction with limited access and not permitting occupancy or storage shall not require sprinkler protection.

Limited access is key here. If a door is used it needs to be of the type that requires a tool to enter and the door does not extend to the floor that would require you to step over.

Dan Wilder

9/26/2022 08:26:21 am

If it meets the requirements of 13-19' 9.2.1 for concealed spaces, sprinkler omission is allowable. No to any footage maximums (in square feet or cubic feet) that I am aware of.

However, a couple keywords stand out to me in the question...

First - "Floor" space in between the roof and top story... - Is this a true floor or mezzanine type area, i.e. walkable?

Second - "Limited Access" - Concealed spaces have the terms "No Access"...what is this limited access entail?

Are there provisions from any other trade in the space? Future build out, HVAC, exit lighting, FA devices?

Based on the face value terms in your question, I would lean toward a sprinkler requirement.

Steven

9/26/2022 09:01:06 am

As others said, I would find it hard to believe that such a large space would not be used for storage or some other occupancy at some point down the road. Of course, adding sprinklers to this area will be a very costly change to the customer, and it's difficult to justify such a change based on only our intuition. I don't know if there are any code references that would explicitly indicate that this area is too large to be considered a concealed space. As such, I think it would be good to discuss with the AHJ to get something "official" which can be used to justify why sprinklers should be added (which is what I think will be what they request).

I had a building with a similar concealed space below the roof level; limited access (access door required maintenance key), prohibited storage, only mechanical and plumbing pipes. In fact, it had a 6'-0" deck height and was less than 20,000 sq.ft. area. Still, the AHJ required sprinkler protection in this area -- I think it was overkill, but they cited that it was a location of potential storage (which is very likely true). Anyways, best to check first and get something in writing.

Todd E Wyatt

9/26/2022 09:58:23 am

2021 IBC would define this space/area as an “ATTIC” (and the AHJ may agree) …

ATTIC. The space between the ceiling framing of the top story and the underside of the roof.

2021 IBC does not define “concealed” but it does reference “concealed” in the following contexts :

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. 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.

The IBC considers an ATTIC a "concealed space" but NOT all "concealed spaces" are ATTICS.

“Concealed” is not referenced in CHAPTER 9 FIRE PROTECTION AND LIFE SAFETY SYSTEMS which determines the SCOPING requirements where an Automatic Sprinkler System (ASPS) is required.
“ATTIC” is referenced (19) time in CHPATER 9 … (15) times in SECTION 903 AUTOMATIC SPRINKLER SYSTEMS :

903.3.1.2NFPA 13R sprinkler systems
Automatic sprinkler systems in Group R occupancies up to and including four stories in height in buildings not exceeding 60 feet (18 288 mm) in height above grade plane shall be permitted to be installed throughout in accordance with NFPA 13R.
The number of stories of Group R occupancies constructed in accordance with Sections 510.2 and 510.4 shall be measured from the horizontal assembly creating separate buildings.

903.3.1.2.1 Protection of decks and balconies.
Decks and balconies greater than 6 feet (1829 mm) above grade, greater than 4 feet (1219 mm) deep, with an area greater than 40 square feet (3.72 m2), and attached to new Group R-1 or R-2 occupancy buildings protected in accordance with Section 903.3.1.2 that are three or more stories in height and with 30 or more units, shall be protected with sprinklers under the balcony or deck framing and under ATTIC eaves when both of the following two conditions exists:
1.The building has an unsprinklered ATTIC.
2.The building has combustible siding.

903.3.1.2.3 ATTICS.
ATTIC protection shall be provided as follows:
1.ATTICS that are used or intended for living purposes or storage shall be protected by an automatic sprinkler system.
2.Where fuel-fired equipment is installed in an unsprinklered ATTIC, not fewer than one quick-response intermediate temperature sprinkler shall be installed above the equipment.
3.Where located in a building of Type III, Type IV or Type V construction designed in accordance with Section 510.2 or 510.4, ATTICS not required by Item 1 to have sprinklers shall comply with one of the following if the roof assembly is located more than 55 feet (16 764 mm) above the lowest level of required fire department vehicle access:
3.1.Provide automatic sprinkler system protection.
3.2.Construct the ATTIC using noncombustible materials.
3.3.Construct the ATTIC using fire-retardant-treated wood complying with Section 2303.2.
3.4.Fill the ATTIC with noncombustible insulation.
The height of the roof assembly shall be determined by measuring the distance from the lowest required fire vehicle access road surface adjacent to the building to the eave of the highest pitched roof, the intersection of the highest roof to the exterior wall, or the top of the highest parapet, whichever yields the greatest distance. For the purpose of this measurement, required fire vehicle access roads shall include only those roads that are necessary for compliance with Section 503 of the International Fire Code.
4.Group R-4, Condition 2 occupancy ATTICS not required by Item 1 to have sprinklers shall comply with one of the following:
4.1.Provide automatic sprinkler system protection.
4.2.Provide a heat detection system throughout the ATTIC that is arranged to activate the building fire alarm system.
4.3.Construct the ATTIC using noncombustible materials.
4.4.Construct the ATTIC using fire-retardant-treated wood complying with Section 2303.2.
4.5.Fill the ATTIC with noncombustible insulation.

The other (4) references to ATTIC are in SECTION 907 FIRE ALARM AND DETECTION SYSTEMS

Franck

9/26/2022 10:21:06 am

As confirmed by others, this is a concealed space (or unoccupied floor, whatever you want to call it) and it does apparently not require a sprinkler protection now. But on the long term ? I have seldom seen such nice “empty” spaces, out of sight, remain empty for a long time.
Normally filled with unused construction features (might be combustible), filters, empty cardboxes and crates, unused computer and electronic equipment, storage area for cleaning products…
It will end up as an attic in a house : storage area for all kind of stuff !
For that reason, if there is an accessible door or opening and if the floor can sustain some weight, I will sprinkler the area at least for an ordinary hazard occupancy.
I have even seen electrical rooms (normally empty except the electrical cabinets), locked and with strict limited access, filled with all kind of storage (generally old furnitures, spare parts and empty boxes)

Very Large Floor/Ceiling Space Still Concealed?

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