NFPA 13R OK in Obstructed Combustible Constr.?

7/8/2024

I have an old existing 3 story building with a basement that is being converted into an apartment building. It used to be a small paint factory.

The architect is calling for a NFPA 13R system, which is understandable since it has all the qualifications for 13R.

However, about 90% of the building is exposed 2x12 construction sitting on 10x14 wood beams. The only areas designated to get ceilings are the bathrooms and some kitchen soffits. That leaves most of the building having obstructed combustible construction, which creates a whole series of problems.

First, I cannot find any residential sprinklers listed for installation below this type of construction. A smooth, flat or sloped ceiling is required for all of them. The AHJ is using the 2019 version of 13R, and Section 6.2.1.3 allows the use of QR sprinklers in dwelling units, but only if there are no more than four sprinklers in the dwelling unit.

All of the dwelling units require more than four sprinklers, so it seems to be that I cannot use 13R at all?

Could someone please tell me if I am interpreting and applying these code sections correctly?

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13 Comments

Pete H

7/8/2024 07:07:35 am

https://www.vikinggroupinc.com/vk467-residential-upright-sprinkler-k49

Check out the Viking Residential Upright Sprinkler. Look at the approval chart.

Note that it has a deflector to ceiling measurement of "1 to 3 inches below 14 inch beams" for ordinary temperature sprinklers at set pressures.

If you're pursuing residential heads, this might help you.

Keith T. (original poster)

7/8/2024 11:03:36 am

Thank you for your reply. I had looked at the Viking Residential Upright sprinkler since I have used it on many other projects, but the listing still refers back to NFPA 13 for ceiling types, and that of course calls for smooth, flat or sloped ceilings. The listing showing the uprights installed below 14" beams was a good call, but the maximum allowed distance between primary beams is 16'-0", and on this project most of the primary beams are 17'-8" apart.

7/8/2024 12:52:47 pm

I see what you're reading on the listing:

"Beam Spacing: A. For primary beams, the distance from the wall to the center of the nearest primary beam must be at least 3’-4” (1.0 m), and not more than one-half the listed sprinkler spacing. Note: Sprinklers may not be required to be located in the first beam nearest the wall. Center-to-center distance between primary beams is to be a maximum of 16 ft (4.9 m). Refer to Figure 3A. B. When beam pockets created by the primary beams exceed 20 ft (6.1 m) in length, secondary beams are required as follows (also refer to Figure 3B): 1. Secondary beam depth must be equal to primary beam depth. 2. Secondary beams must be placed so that the bays formed by the primary beams do not exceed 20 ft (6.1 m) in length. C. When primary beam spans do not exceed 20 ft (6.1 m), secondary beams (not required) may have any distance from wall to nearest secondary beam and any distance center to center between secondary beams. Refer to Figure 3C."

You can have your primary beams spaced between 16'-0" and 20'-0" without requiring secondary beams and still use this sprinkler.

The catch is, you just need more than one head per bay. You can't have center to center of sprinklers be 16'-0" and expect that to cover the full distance when the beam distance is greater than 16'-0" between beams.

---

Secondly on 13's rules of ceiling type for sprinklers, I'm going 2016 edition because it's what I know best and I don't know what edition you're on:

8.10.2.2 Residential sprinklers shall not be permitted to be used on ceilings with slopes greater than 8 in 12 or ceiling with heights greater than 24 ft unless specifically listed for this purpose.

--

I don't see where you're seeing the call for the ceiling to be smooth or flat? Especially as it goes on to show minimum distance from trusses and other ceiling mounted obstructions in the chapter. I'll give a quick check in 13R.

--

Okay, yeah, not seeing any requirements for flat or smooth ceilings in 13R. Heck 13R specifically calls out "flat, horizontal beamed ceiling" as one of the basic design types for a four head calculation in 2016 edition 7.1.1.3.1(2). A maximum of 14" beams. The compartment containing the beamed ceiling where you are calculating your four heads shall be no more than 600 square feet, but that's a design area limitation, not an installation limitation.

All of this to say...

your ceilings are under 24 feet high, right?

7/8/2024 01:01:03 pm

Looking more at the cut... there is no figure 3C on the cut, I think Viking may have forgotten to update part of their listing. I still see no reason, given figures 4A and 4B, you cannot have your lines slightly off underneath the beams 17'-8" (as shown in figure 2 on the cut) apart and then a center line of heads spaced 9'-0" (the minimum the cut calls for) away from those lines at the same elevation.

But I could be wrong.

7/8/2024 01:14:11 pm

Aaaaand now I see you're on 2019 edition which does call out:

12.1.1 (2) a flat, horizontal, beamed ceiling, with a maximum height of 24 ft with beams up to 14 inch deep with pendent sprinklers under the beams. The compartment containing the beamed ceiling shall be a max. of 600 square feet in area....

Okay, yeah, for this NFPA 13 would restrict residential sprinklers in beamed spaces to only be acceptable if the compartment is under 600 square feet.

But I don't know why that would apply in 13R. Check the corresponding parts in 2019 13R and see if it would cause an issue.

Anthony

7/8/2024 07:15:04 am

You can still use 13R and do a light hazard calculation. 13R has other benefits to cost reduction other than the number of heads in a calculation.

7/8/2024 11:14:53 am

I have to disagree with this comment. Section 6.2.1.1 in the 2019 NFPA 13R states "Listed residential sprinklers SHALL be used unless another type is permitted by 6.2.1.3 or 6.2.1.4 (6.2.1.4 is about allowing quick-response sprinklers in mechanical closets, so it does not apply) Since we cannot use residential sprinklers due to the obstructed construction, and Section 6.2.1.3 only allows the use of QR sprinklers up to a maximum of four heads per dwelling unit, I don't believe a 13R design is possible.

Todd E Wyatt

7/8/2024 08:41:21 am

The scoping Code (e.g. IBC-2021) identifies WHERE an automatic sprinkler system (ASPS) is required based on the Occupancy Classification(s) (OC) assigned to the building (Group R-2) and/or “Specific Building Areas and Hazards”, not the Type of Construction (TC) of the building.

The referenced ASPS standard (e.g. NFPA 13-2019 or NFPA 13R-2019) prescribes HOW a building’s/structure’s ASPS is to be designed, installed, inspected, and maintained.

If the Design Professional (e.g. Architect) confirms that a NFPA 13R ASPS standard is applicable, the Project must meet the following (3) conditions 903.3.1.2 :

IBC-2021
Chapter 9 Fire Protection and Life Safety Systems
Section 903 Automatic Sprinkler Systems
903.2 Where Required
903.2.8 Group R
903.2.8 Group R
An automatic sprinkler system installed in accordance with Section 903.3 shall be provided throughout all buildings with a Group R fire area.
903.3 Installation Requirements
903.3.1.2 NFPA 13R Sprinkler Systems
Automatic sprinkler systems in Group R occupancies shall be permitted to be installed throughout in accordance with NFPA 13R where the Group R occupancy meets all of 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.
The number of stories of Group R occupancies constructed in accordance with Sections 510.2 and 510.4 shall be measured from grade plane.

IF the Project meets all (3) of these conditions, then the ASPS is “permitted” to use NFPA 13R … it is not required to, however. NFPA 13 can be used instead.

7/8/2024 10:39:59 am

"I have an old existing 3 story building with a basement that is being converted into an apartment building. It used to be a small paint factory."

This is a Change of Occupancy (Group F Industrial to Group R-2). The Design Professional would start their Code Review in the applicable edition of the International Existing Building Code (IEBC) which would then sends them to the adopted IBC :

IEBC-2021
Chapter 10 Change of Occupancy
Section 1004 Fire Protection
1004.1 General
Fire protection requirements of Section 1011 shall apply where a building or portions thereof undergo a CHANGE OF OCCUPANCY CLASSIFICATION or where there is a change of occupancy within a space where there is a different fire protection system threshold requirement in Chapter 9 of the INTERNATIONAL BUILDING CODE.

Section 1011 Change of Occupancy Classification
1011.2 Fire Protection Systems
1011.2.1 Fire Sprinkler System
Where a change in occupancy classification occurs or where there is a change of occupancy within a space where there is a different fire protection system threshold requirement in Chapter 9 of the International Building Code that requires an automatic fire sprinkler system to be provided based on the new occupancy in accordance with Chapter 9 of the International Building Code. The installation of the automatic sprinkler system shall be required within the area of the change of occupancy and areas of the building not separated horizontally and vertically from the change of occupancy by one of the following:
1. Nonrated permanent partition and horizontal assemblies.
2. Fire partition.
3. Smoke partition.
4. Smoke barrier.
5. Fire barrier.
6. Fire wall.
Exceptions:
An automatic sprinkler system shall not be required in a one- or two-family dwelling constructed in accordance with the International Residential Code.
Automatic sprinkler system shall not be required in a townhouse constructed in accordance with the International Residential Code.
The townhouse shall be separated from adjoining units in accordance with Section R302.2 of the International Residential Code.

Jack G

7/8/2024 10:08:40 am

Hmmmm. I m not sure that I agree.
First please refer to your Meyer fire cheat sheet for 13, 13r, 13d.
Next, please check the requirements from the IBC. This was originally a commercial building. So a change of occupancy was filed? “ Correct ?” If not it remains the original occupancy, with areas of light and ordinary hazard.
The Meyer fire cheat sheet takes you thru the code requirements. I
For R-2, V-A, V-B, 3 stories looks good for 13 r. 504.4.
If an area increase was taken for the new work 506.2, 13r,13d does not apply here. Please refer to the code sheet in the building plans for your project.
It covers ( Meyer fire cheat sheet) the codes separated under 13,13r, 13d in a logical sequence for the IBC code.
I first saw a table like this in the commentary code IBC in 2006. Still in the commentary code.
Not allowed rating reductions ( for partitions ) nor allowed dead end corridors. ( separated occupancies or fire partitions) check the requirement for residential and non residential draft stopping.
All areas are to be protected per 908.2.8.
Also check 1005. 3, 1028.1, and 1017.2 referring to egress to see if what is on the drawings is applicable.
Area increases per 506.2 are not permitted for 13r protection systems.
The use of QR or residential sprinklers per 13 is an option.
If it were me, I would propose a 13/system, and use QR with a hydraulic area reduction ( 900 sq feet ) which may only be 8-9 heads or less if you find the architectural code sheet does note meet the building code requirements ( propose a change order)
Please remember with a QR area reduction or a unit calculation method, you must include small room sprinklers in your calculation. ( omitted in a normal 13 calculation.
If still listed as an S occupancy ( no occupancy change) a 13 system is still applicable.
So in summary, I ve found I ve had to redesign buildings to applicable standards as the building owner wants “ cheap-cheap” and the architect may comply with “ tunnel vision” looking at just one code book, 13 r, 13 d etc. Opinion .
In roughly 2013, or so, A bunch of apartment buildings 5 I think burned to the ground from a fire in one of the buildings ( were occupied) unsprinklered attics, down to the ground, in the King of Prussia/ conshehawkin area of pa. (. A hotweld the culprit)
Everyone was on board for this design. I didn’t get the contract as I had attic heads figured ( was an old paint factory converted to apartments)
From what I remember Everyone got sued including the AHJ for the design, and CYA paragraphs.
Re built them with attic sprinklers
Be careful. Not everything is correct on the plans and specs. ( 56 years in the fire sprinkler business )
Opinion.

7/8/2024 12:12:20 pm

"In roughly 2013, or so, A bunch of apartment buildings 5 I think burned to the ground from a fire in one of the buildings ( were occupied) unsprinklered attics, down to the ground, in the King of Prussia/ conshehawkin area of pa. (. A hotweld the culprit)."

If they reviewed the adopted IBC (e.g. 2012?), they would have found that attics were not exempted from protection by Automatic Sprinkler System (ASPS) in Group R OCs since they are required to be provided with an ASPS throughout :

IBC-2012
Chapter 9 Fire Protection and Life Safety Systems
Section 903 Automatic Sprinkler Systems
903.2 Where Required
903.2.8 Group R
An automatic sprinkler system installed in accordance with Section 903.3 shall be provided THROUGHOUT all buildings with a Group R fire area.

In more recent editions, an attic can be exempted from ASPS protection in NFPA 13R systems if it meets 903.3.1.2.3 :

IBC-2021
Chapter 9 Fire Protection and Life Safety Systems
Section 903 Automatic Sprinkler Systems
903.3 Installation Requirements
903.3.1 Standards
903.3.1.2 NFPA 13R Sprinkler Systems
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 fire department vehicle access needed to meet the provisions in Section 503
a. .Provide automatic sprinkler system protection.
b. Construct the attic using noncombustible materials.
c. Construct the attic using fire-retardant-treated wood complying with Section 2303.2.
d. 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:
1) Group R-4, Condition 2 occupancy attics not required by Item 1 to have sprinklers shall comply with one of the following:
a. Provide automatic sprinkler system protection.
b. Provide a heat detection system throughout the attic that is arranged to activate the building fire alarm system.
c. Construct the attic using noncombustible materials.
d. Construct the attic using fire-retardant-treated wood complying with Section 2303.2.
e. Fill the attic with noncombustible insulation.

7/8/2024 10:31:47 am

I ve replied above and would like to add that is beneficial to buy the straight code book, AND the commentary version as it provides explanations and examples. The same holds true with NFPA phamplets—- IE NFPA 13 , 14, 20, and the automatic sprinkler,standpipe and pump handbooks.
I ve found them to be very valuable, if you can budget their costs.
Opinion.

7/8/2024 01:32:26 pm

Exactly. Arch, Eng, AHJ, put out a set of documents that were not correct. Major fire.
It’s up to us to verify the documents and red flag them.
And in some cases, walk away.

NFPA 13R OK in Obstructed Combustible Constr.?

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