John Lansing
@pipedreaming.bsky.social
Plumbing, building codes, engineering design guides, water and nutrient cycle, architecture, embodied carbon, development, cities, and the international variations of them all
It’s easy to see how multiple codes and hundreds of local tweaks with additional restrictive rules creates an environment that encourages overdesign to avoid project delays, redesign, and liability.
November 25, 2025 at 5:47 PM
It’s easy to see how multiple codes and hundreds of local tweaks with additional restrictive rules creates an environment that encourages overdesign to avoid project delays, redesign, and liability.
Yes, more often than 917 but it’s not as utilized as much as it should be, likely because it’s illegal in so many other places. Design engineers tend to stick with configurations they know will be accepted by the AHJs in various projects in different cities to avoid surprise plan check comments.
November 25, 2025 at 5:47 PM
Yes, more often than 917 but it’s not as utilized as much as it should be, likely because it’s illegal in so many other places. Design engineers tend to stick with configurations they know will be accepted by the AHJs in various projects in different cities to avoid surprise plan check comments.
I generally recommend a 3 inch stack regardless when serving more than ~5 floors of sinks due to grease and food debris accumulations that can easily close off diameter of a 2 inch drain. For the horizontal drain downstream of the stack, a minimum of 2% gradient is critical.
November 25, 2025 at 7:29 AM
I generally recommend a 3 inch stack regardless when serving more than ~5 floors of sinks due to grease and food debris accumulations that can easily close off diameter of a 2 inch drain. For the horizontal drain downstream of the stack, a minimum of 2% gradient is critical.
This is a great question and one that becomes even more important when looking at scenarios where the building is too tall for a 4 inch single stack. As for the 2 inch vs 3 inch considerations on a kitchen sink stack…
November 25, 2025 at 7:29 AM
This is a great question and one that becomes even more important when looking at scenarios where the building is too tall for a 4 inch single stack. As for the 2 inch vs 3 inch considerations on a kitchen sink stack…
I’m always shocked when going to the East Coast by how bad the situation really is. I’d say NYC is an exception (GrowNYC has one of the top 5 best farmers markets I’ve been to anywhere) but even the best grocery stores in DC can’t compare to what you can find in even Eugene or Olympia.
November 25, 2025 at 7:13 AM
I’m always shocked when going to the East Coast by how bad the situation really is. I’d say NYC is an exception (GrowNYC has one of the top 5 best farmers markets I’ve been to anywhere) but even the best grocery stores in DC can’t compare to what you can find in even Eugene or Olympia.
Abundant varieties of fresh produce is one of the most underrated things about the West Coast.
November 25, 2025 at 6:35 AM
Abundant varieties of fresh produce is one of the most underrated things about the West Coast.
The UPC unfortunately doesn’t have an equivalent to 913 or 917. Even the horizontal wet vent configuration was introduced only a few code cycle ago in the 2015 UPC.
November 25, 2025 at 4:00 AM
The UPC unfortunately doesn’t have an equivalent to 913 or 917. Even the horizontal wet vent configuration was introduced only a few code cycle ago in the 2015 UPC.
Yes, washing machines are allowed in Section 913 variation of the single stack.
November 25, 2025 at 3:45 AM
Yes, washing machines are allowed in Section 913 variation of the single stack.
The explanation for why WCs are prohibited in Section 913 is very limited, but the problem poses no real issues in a 4 inch drainage stack, except in very tall buildings. What’s funny is WCs are allowed in Section 917, but the stack base clearance zone poison pill applies.
![913-WASTE STACK VENT
913.1 Waste stack vent permitted. A waste stack shall be considered to be a vent for all of the fixtures discharging to the stack where installed in accordance with the requirements of this section.
C A waste stack vent uses the waste stack as the vent for fixtures other than urinals and water closets. The principles of use are based on some of the original research that was done in development of the first plumbing codes. The system has been identified by a variety of names, including vertical wet vent, Philadelphia single-stack and multifloor stack venting. Note that due to the oversized design of a waste stack vent system, a vent stack is not required and thus, a relief vent is not required (see Section 904.2, Exception).
913.2 Stack installation. The waste stack shall be vertical, and both horizontal and vertical offsets shall be prohibited between the lowest fixture drain connection and the highest fixture drain connection. Fixture drains shall connect separately to the waste stack.
The stack shall not receive the discharge of water closets or urinals.
C Because the drainage stack serves as the vent, there are certain limitations on the design to prevent pressures in the system from exceeding plus or minus 1 inch of water column (249 Pa). The system is identified as a waste stack vent because it prohibits the connection of water closets and urinals. Only waste may discharge to the stack.
Water closets and some urinals have a surging discharge that results in too great a pressure fluctuation in the system.
The system can serve sinks, lavatories, bathtubs, bidets, showers, floor drains, drinking fountains and standpipes.
To preserve the desirable annular flow in the [text overrun]](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:zrfppf44vjnvtplygmvbk5we/bafkreidrxuongawimu7pb75p2nxzfnaddbvn52o5jju5mdcnsyxjc3d4aq@jpeg)
November 25, 2025 at 3:39 AM
The explanation for why WCs are prohibited in Section 913 is very limited, but the problem poses no real issues in a 4 inch drainage stack, except in very tall buildings. What’s funny is WCs are allowed in Section 917, but the stack base clearance zone poison pill applies.
(Just an unrelated side note, the bends in the original image should say “1/8” not “1/4”.)
November 25, 2025 at 3:23 AM
(Just an unrelated side note, the bends in the original image should say “1/8” not “1/4”.)
Even Canada allows the vent piping to be eliminated for installations like this, which is essentially a single stack that prohibits WCs. Good enough for Copenhagen, London, Frankfurt, Vancouver, Paris, Miami, and Nashville but not NYC, San Francisco, Seattle, Houston, Los Angeles, ect.
November 25, 2025 at 3:19 AM
Even Canada allows the vent piping to be eliminated for installations like this, which is essentially a single stack that prohibits WCs. Good enough for Copenhagen, London, Frankfurt, Vancouver, Paris, Miami, and Nashville but not NYC, San Francisco, Seattle, Houston, Los Angeles, ect.
Can’t say if this installation was under the 1938 NYC building code or the 2022. 🙃
November 25, 2025 at 3:19 AM
Can’t say if this installation was under the 1938 NYC building code or the 2022. 🙃
Not once have I seen this compact arrangement of plumbing fixtures in a double loaded corridor building. I see this all the time in single stair buildings though. This can eliminate so much lost energy waiting for hot water, as well as water supply and drainage piping.
November 23, 2025 at 6:47 PM
Not once have I seen this compact arrangement of plumbing fixtures in a double loaded corridor building. I see this all the time in single stair buildings though. This can eliminate so much lost energy waiting for hot water, as well as water supply and drainage piping.
On the plus side, they don’t have heat pumps and therefore no GHGs or HFCs!
November 23, 2025 at 6:53 AM
On the plus side, they don’t have heat pumps and therefore no GHGs or HFCs!
The countertop ones (like this one) unfortunately don’t typically have a heat pump and aren’t be very effective in a bathroom. It might be better than nothing though.
TABYIK Dehumidifiers for Home, 42oz Dehumidifier for Bathroom, Dehumidifiers for Room with Auto Shut Off, Auto Defrost Quiet Dehumidifier for Bedroom Wardrobe Closet Trailer RV
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November 23, 2025 at 6:51 AM
The countertop ones (like this one) unfortunately don’t typically have a heat pump and aren’t be very effective in a bathroom. It might be better than nothing though.
That’s awful. I’ve had a bad but operational exhaust fan before and had a portable dehumidifier to help tackle the humidity issue. I wonder if the landlord would pay for one since they are not meeting a requirement in the mechanical code (Table 403.3.1.1 of the Oregon Mechanical Specialty Code)?
Haier ENERGY STAR® 35 Pint Portable Dehumidifier with Smart Dry for Very Damp Spaces|^|QDHR35LZ
www.haierappliances.com
November 23, 2025 at 6:23 AM
That’s awful. I’ve had a bad but operational exhaust fan before and had a portable dehumidifier to help tackle the humidity issue. I wonder if the landlord would pay for one since they are not meeting a requirement in the mechanical code (Table 403.3.1.1 of the Oregon Mechanical Specialty Code)?
Do you know if this is the case in everyone’s unit or is it a faulty fan inside your bathroom?
November 23, 2025 at 5:40 AM
Do you know if this is the case in everyone’s unit or is it a faulty fan inside your bathroom?
19th century methods relied on windows, which had been disincentivized in the UK with the Window Tax, repealed in 1850.
November 23, 2025 at 5:31 AM
19th century methods relied on windows, which had been disincentivized in the UK with the Window Tax, repealed in 1850.
Cleaning the air at each stop. Nice!
November 23, 2025 at 5:07 AM
Cleaning the air at each stop. Nice!
There’s so much you can do with air quality sensors. Hydrogen sulfide and ammonia sensors can be used as a proxy to know when public restroom maintenance is needed.
November 23, 2025 at 5:06 AM
There’s so much you can do with air quality sensors. Hydrogen sulfide and ammonia sensors can be used as a proxy to know when public restroom maintenance is needed.
Wow, are those at each seat?
November 23, 2025 at 4:50 AM
Wow, are those at each seat?
ARUP’s Shanghai office has some really nice CO2 sensors scattered throughout with readings featured on a public display panel.
November 23, 2025 at 4:48 AM
ARUP’s Shanghai office has some really nice CO2 sensors scattered throughout with readings featured on a public display panel.