Standpipe Req'd, Supply Size for Small Building?

6/6/2022

According to the International Building Code Section 905.3 (2018 Edition), a standpipe is required in any building with four or more stories.

We have a small building (three family homes) but the first floor is all a parking garage, and then 3 more floors over the parking garage (one home per floor).

According to the IBC, do we still need a standpipe even if it's such a small building?

If we do need a standpipe, does the service have to be 4-inches or can we have it at 2-inches and increase the riser up to 4-inches to feed the manual wet standpipe?

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11 Comments

Alex

6/6/2022 07:04:10 am

Hi,

IBC (2018) 905.3.1 outlines the maximum height until standpipes are required.

You are correct, if you have four or more stories, your building requires standpipes. Although, the code goes on to read if the floor of the height story is located more than 30 feet above the lowest level of fire department access, you also require standpipes. My guess, from your question, is that you will exceed 30 feet.

NFPA 14 7.6.1 states that for a Class III standpipe, the minimum diameter is 4 inches. NOW, you have me thinking. Where does the standpipe system "start"? Is it after your backflow? At the first flange in the building? What if your service is 2 inches, you install a reducer to get to 4". Then go through your backflow? I dont see any issues with that as long as all hydraulic calculations work and are done accurately. What are others thoughts on this?

Thanks
Alex

Pete H

6/6/2022 07:37:26 am

I'm inclined to agree with Alex, you need the standpipe (you got four stories). And to continue to agree, you can probably get away with the 2" service that increases to 4" at the riser (so after the backflow) provided you can make the mandatory calculations work.

However, the 2" Backflow and service will make it a lot harder to make those calculations work without an extremely fortunate water supply. So good luck.

Anthony

6/6/2022 08:56:27 am

No calculations required, It would be a manual standpipe system, assuming there is a sprinkler system. The 2'' backflow it a sprinkler problem, not a standpipe problem.

Alex

6/6/2022 01:19:07 pm

Anthony,

I still calculate manual standpipes. Determine what flow/pressure the local Fire Department Engines can provide and ensure that your pipe sizes work.

In my opinion, calculations for everything should be required. They are so simple to provide and ensure the design actually works.

Alex

Todd E Wyatt

6/6/2022 08:49:05 am

The first step in evaluating fire protection requirements is to identify the Occupancy Classifications (OC) of the building. You state that the building includes "three family homes" which could be classified as Group R-2 Residential. (Standpipes are not required in R-3 occupancies).

As Alex has identified, there are (3) building height/stories conditions that require Class III standpipes but (6) exceptions to these requirements. "Section 905 Standpipe Systems" then goes on to identifiy individual requirements based on the Occupancy Classifications (e.g. Group A) and/or special conditions (e.g. Underground buildings).

Once you determine IF a standpipe system is required based on building height and/or OC/special conditions, the next step is to determine where Class I, II, and III standpipes are to be located. In your case, the standpipes' locations may be different for the Group S-2 Low-Hazard Storage (parking garage) portion and the Group R Residential portion.

M. Newell

6/6/2022 08:49:23 am

I think it largely depends on the occupancy above your parking garage.

If it is an R-3 the IBC does not require it to have a standpipe even if over 30’ above FD access.

If it is not an R-3 then when you are over 30’ you would likely need to have a standpipe.

You could likely look into a manual standpipe if needed and if allowed per your local codes. This would allow you to size your standpipe from the supply of a fire fighter apparatus and eliminate the potential need for a fire pump.

Then you would need your standpipe to come off the end of your system similar to an end of system FDC.

Dan Wilder

6/6/2022 08:58:56 am

Points of clarification:

Is the garage for the units specifically or is it publicly accessible?
Is the building over 60' tall? (the top of roof, not highest occupiable floor)

The design (assumption) is based on a 13R approach to the standpipes as a manual wet, 4" minimum sizing and FDC.

NFPA 14 A.6.3.4.5 has a little bit stating: "...common scenario is to connect the system to the potable water system (the automatic water supply for sprinklers & hence a likely back flow requirement)...There is no minimum size requirement for this connection."

The standpipe start point (in my mind) needs to be identified as from the location of the FDC to the feed main to the standpipe(s). The automatic water supply location feed to wherever it ties into the standpipe can be sized per calculations and would not be required to be up sized to the minimum.

The best visual aid I can find is NFPA 14 19' Ed Figure A7.10.1.1.6 for the riser and FDC being separately located but tie into each other. Those pipe sizes can be different up until that tie in point, then the larger requirement (the 4" or whatever the calc shows is needed) overrides the automatic source sizing.

Todd E Wyatt

6/6/2022 10:01:02 am

2021 IBC

905.3 Required Installations
Standpipe systems shall be installed where required by Sections 905.3.1 through 905.3.8. Standpipe systems are allowed to be combined with automatic sprinkler systems.

Exception: Standpipe systems are not required in Group R-3 occupancies.

[F] 905.3.1 Height
Class III standpipe systems shall be installed throughout buildings where any of the following conditions exist:
1. Four or more stories are above or below grade plane.
2. The floor level of the highest story is located more than 30 feet (9144 mm) above the lowest level of fire department vehicle access.
3. The floor level of the lowest story is located more than 30 feet (9144 mm) below the highest level of fire department vehicle access.

Dan Wilder

6/6/2022 11:04:40 am

My request was not to remove the standpipe requirement but identify if a 13R system is even the correct application. If the building goes to a full 13 due to the height of the building, a 2" domestic water feed isn't going to cut it.

I recently had a 3 story building, as identified within the local predesign IBC/IFC, which had 22' between floors. The setup was similar to a loft style with the front living area & windows being the full height of the floor and the back area having the bedrooms and bath on a "mezzanine" over the kitchen and lower RR/closets/entry. The building initially was designed as being sprinklered per 13R (multiple units) in plan review with the Building Department, but the height of the building required a full 13 system once the fire department saw the plans. Required a full redesign once they (the arch) lost the appeal and the owner didn't want to lose floor heights.

Ed Kramer

6/6/2022 11:33:07 am

Designed a project a few years ago that required a manual wet Class I standpipe. The standpipe system (from the most remote hose valve to the FDC) was sized via hydraulically calculations. Most of the standpipe system was 4" with some of the common supply pipe near the FDC as 6". I don't recall the reasoning, but we chose to run a separate vertical supply for the sprinkler system, so the standpipe was standpipe only - not a combined system. To make the standpipe 'wet', we connected it to the sprinkler system riser using 1" pipe.

Jesse

6/6/2022 02:44:11 pm

Its not stories, per se. But rather vertical distance of the occupiable floors above lowest level of fire apparatus access. I actually have a 4 story hotel right now with the 4th floor 28-6 above the fire lane so it has no standpipe. Likewise, I had a 3 sto prior that did.

And I always calculate manual standpipes.

Standpipe Req'd, Supply Size for Small Building?

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