Spr. Omission in Overhang Limited to 4-ft Width?

9/27/2021

I have a flat exterior canopy that projects 10-feet from the building, constructed of 2x solid wood joists, ceiling attached directly to the underside, roof sheathing directly to the top.

There is no storage beneath the canopy; the area below would be considered light hazard.

I am having the architect change the sheathing attached directly to the underside from plywood to cement board, so I think I will meet the criteria to allow sprinklers to be omitted from beneath, per NFPA 13 Section 8.15.7.3 (2016 Edition), or Section 9.2.3.3 (2019 Edition), confirmed by the MeyerFire Canopy, Overhang, & Exterior Projection decision tree cheat sheet. (I realize I might have to take a closer look at the exposed material of the roofing.)

NFPA treats the area below, and the concealed space within the canopy separately. There are the combustible concealed space exceptions.

In my canopy, does the 4-foot width limit of 8.15.1.2.1.2 (2016), 9.2.1.19.2 (2019) mean I have to sprinkler the joists channels, or does the combustible concealed space omission of 8.15.1.2.5 (2016), 9.2.1.5(2019) overrule?

NFPA 13 9.2.1.5 (2019): Concealed spaces formed by ceilings attached directly to or within 6-inches of ... solid member construction shall not require sprinkler protection.

NFPA 13 9.2.1.19.1: Sprinklers shall be permitted to be omitted from within combustible... overhangs... that are constructed in accordance with 9.2.1.19.2 through 9.2.1.19.5.
NFPA 13 9.2.1.19.2 (2019): Combustible soffits, eaves, overhangs... shall not exceed 4-feet in width.

I’m thinking the section for sprinklering within canopies is more applicable to canopies with a larger void space within, that may not meet the usual combustible concealed space exceptions, where you’d have to make some minor modifications, no openings, and add draft-stopping to omit sprinklers from within the space.

The architect said on a canopy similar to this one, they had to fill the 2x joists channels with insulation, but I don’t where code would direct us to do this, unless they were TJI’s.

Does the 4-foot width limit specific to Exterior Soffits, Eaves & Overhangs overrule the Concealed Space Rules?

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15 Comments

Pete

9/27/2021 06:46:55 am

Are you in 2016 or 2019?

Alex

9/27/2021 07:35:46 am

Hi Anonymous,

A few points I picked up from your question:
- On the past canopy where they had to insulate to omit sprinkler protection, I would refer to NFPA (2016) 8.15.1.2.7 “concealed spaces filled with noncombustible insulation shall not require sprinkler protection”.
- I believe you are interoperating 8.15.1.2.1.2 (2016) incorrectly. I believe the code is driving at allowed openings within a ceiling. For instance, if your office has an ACT with a supply grill greater than 4 feet in length, it cannot exceed 8 inches in width. This section does not dictate allowed width of canopies or overhangs.

As far as your question is concerned, I believe that sprinklers are required within the canopy since you are greater than 4 feet in width. Although, I would insulate each pocket per 8.15.1.2.7 to omit the sprinkler requirements.

Best of luck with your design,
Alex

John link

9/27/2021 08:40:53 am

I agree with Alex, however at 10' wide, throw in some sidewalls or dry sidewalls (if in a cold area that gets below 40 degrees).

Steven

9/27/2021 09:09:45 am

I might be missing something, but I agree with the original poster in that the requirements of NFPA 13 Section 8.15.7.3 (2016) are fully met in this situation, allowing sprinkler coverage below the canopy to be omitted (assuming the exposed roof material is limited-combustible). In addition, Section 8.15.1.2.3 (2016) permits sprinklers to be omitted from within the joist channels. It is my understanding thus that sprinklers would not be required in neither the concealed space nor the space below.

9/27/2021 09:42:44 am

Correction: I meant 8.15.1.2.5, not 8.15.1.2.3. However, I am looking at 8.15.1.2.18 and wondering if that will override the allowance of 8.15.1.2.5? I do think it would be very impractical to have to protect every joist channel, and would not meet the intent of the code.

Jesse

9/27/2021 09:10:45 am

Architects love their canopies.

Yeah, I think the overhang needs to be protected. And I think dry horizontal sidewalls would be my first choice.

The combustible concealed space is also an issue. My first choice would be to provide N/C insulation.

There is also an exclusion n 2016 NFPA 13 8.15.1.2.4 I've used where the "ceiling" attaches to the bar joist and the roof deck is directly above.

SCHULMAN

9/27/2021 09:13:08 am

solid 2x wood joists = combustible construction ...
don't see how the change in sheathing helps you ....
missing something ?

Dustin

9/27/2021 10:20:54 am

The 8.15.7 (2016) Exterior Projection provisions apply to both combustible and non-combustible construction whereas the 8.15.1.2.18 (2016) Exterior Soffits, Eaves, Overhangs apply only to combustible construction. The two sections speak to different architectural features but have no associated definitions as part of the standard.

Your feature sounds like it can be argued as an exterior projection with 8.15.1.2.5 (2016) applying inside the canopy and 8.15.7.3(2) (2016) applying below, provided you meet the 160cuft requirement.

Anonymous

9/27/2021 10:49:48 am

Generally, sheathing alone wouldn't matter as it's the entire construction per 8.15.7.2 (2016) 9.2.3.2 (2019) however the following section (2019 shown) allows another scenario, describing the "exposed finish material:"

9.2.3.3 Sprinklers shall be permitted to be omitted from below the exterior projections of combustible construction, provided the exposed finish material on the exterior projections are noncombustible, limited-combustible, or fire retardant–treated wood as defined in NFPA 703, and the exterior projections contain only sprinklered concealed spaces or any of the following unsprinklered combustible concealed spaces:

(1) Combustible concealed spaces filled entirely with
noncombustible insulation

(2) Light or ordinary hazard occupancies where noncombustible
or limited-combustible ceilings are directly attached
to the bottom of solid wood joists so as to create enclosed
joist spaces 160 ft3 (4.5 m3) or less in volume, including
space below insulation that is laid directly on top or
within the ceiling joists in an otherwise sprinklered attic
[see 19.3.3.1.5.2(4)]

(3) Concealed spaces over isolated small exterior projections
not exceeding 55 ft2 (5.1 m2) in area

So my intent was to meet #(2) with the non-combustible sheathing, since attached directly to solid wood joists (not-composite wood joists), although I have seen an informal interpretation questioning if exposed finish material includes the roof.

I guess in my view the question boils down to:

Does the combustible concealed space exception "Concealed spaces formed by ceilings attached directly to or within 6-inches of ... solid member construction shall not require sprinkler protection." apply to the concealed space within a canopy similarly constructed, or does the "Overhang" section, where four criteria must be met, including not exceeding 4 ft., apply? I'm thinking this limitation is intended for more "hollow" canopies to allow an exception for such an exterior architectural feature, but at the same time ensuring the fire cannot spread into the building. (It's odd the 2016 handbook includes a photo of such a canopy of triangular cross-section, but the 2019 handbook does not.)

Thanks all, for what appeared to me a simple question, I thought I was having a senior moment until I dug into it deeper. On this project, they ended up supporting the overhang with an exposed Glu-Lam Beam (common around these parts) so I will protect below anyway, which I believe is prudent because while storage below is not planned, cannot be guaranteed.

Speaking of throw of dry sidewalls, I am also often asked a related question: If sidewalls protect a smooth-ceiling beneath an exterior canopy projection, and sufficiently reach out to a supporting beam (wood or steel), can a remaining cantilevered overhang beyond the beam be ignored IF that portion is less than 4 ft. wide? (Like a non-sprinklered <4' canopy extension beyond a sprinklered canopy?)

David Kulbacki

9/28/2021 05:07:22 pm

I'm with you anonymous. I've addressed this situation by implementing 9.2.3.3 option (1), (2), or (3) for this kind of space.

Ritz

9/27/2021 11:54:46 am

I think the cart is before the horse here. What state are you in?

Assuming you are using the IBC. The building code tells you what you must do and the reference standards tell you how to do it. Until they conflict.

That being said in the IBC for new buildings Section 603 and section 705 and 1406.3 are applicable. Depending on the type of building construction, fire separation distance and projections construction different materials are required.

There is also a cavate in 102.4.1 Conflicts. Where conflicts occur between provisions of this code and referenced codes, standards the provisions of this code shall apply.

102.4.2 Provisions in reference codes and standards. Where the extent of the referenced standard code or Standard includes subject matter that is within the scope of this code, of the codes listed in Section 101.4, as applicable, Shall take precedence over the provisions in the referenced code or Standard.

The code controls in this case over NFPA 13 for projections.

I am not saying you should not sprinkler the projections I am saying it may not be required and you may have to use fire retardant treated wood as per code.

Any thoughts?

Mike

9/27/2021 04:59:03 pm

What did the estimator who landed the job plan for?

9/28/2021 05:06:55 pm

I've addressed this situation by implementing 9.2.3.3 (2016 edition) option (1), (2), or (3) for this kind of space.

8.15.1.2.3 and 8.15.1.2.5 have been recommended by a few people, but I wouldn't use those unless you want to increase your design area to 3,000 sqft. Don't forget to look at 11.2.3.1.5.2 to verify that your solution doesn't trigger a design area increase.

9/29/2021 01:28:13 pm

Thanks, David (and all), I think you may have mixed the 2019 vs. 2019, but I see what you are saying, good point about the 3,000 sq. ft. It is often overlooked, that IF one takes advantage of one on the combustible concealed-space omissions, UNLESS you fit into one of the 11.2.3.1.5.2 (2016) / 19.3.3.1.5.2 (2019), you do trigger the 3,000 sq. ft. R/A for adjacent areas.
Anyway, I realized I partly made the rookie mistake of forgetting to analyze the numbering sequence of the applicable sections - The "Exterior Soffits, Eaves, Overhangs, and Decorative Frame Elements" and it's sub-sections is merely one of the (for now) 18 allowable combustible concealed space exceptions, and in my opinion does not in itself supersede any of the other 17 sections.
No estimator involved, I am working with an owner/architect providing input for a balance of prudent, code-compliant fire protection within the framework of their still-evolving design, in part trying to avoid pitfalls, surprises ("that ugly sprinkler pipe"), and CO's later.

10/1/2021 10:49:07 am

Yes, my apologies, I meant 8.15.7.3 (2016 edition) not 9.2.3.3.

Spr. Omission in Overhang Limited to 4-ft Width?

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