• Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • PRODUCTS
  • CONTRACTORS
  • ENGINEERS
  • RADIANT & HYDRONICS
  • INSIGHTS
  • MEDIA
  • RESOURCES
  • EMAGAZINE
  • SIGN UP!
cart
facebook instagram twitter linkedin youtube
  • PRODUCTS
  • FEATURED PRODUCTS
  • CONTRACTORS
  • BATH & KITCHEN PRO
  • BUSINESS MANAGEMENT
  • HIGH EFFICIENCY HOMES
  • TECHNOLOGY
  • WATER TREATMENT
  • PMC COLUMNS
  • PMC COLUMNS
  • Dave Yates: Contractor’s Corner
  • John Siegenthaler: Hydronics Workshop
  • Kenny Chapman: The Blue Collar Coach
  • Matt Michel: Service Plumbing Pros
  • Scott Secor: Heating Perceptions
  • ENGINEERS
  • CONTINUING EDUCATION
  • DECARBONIZATION | ELECTRIFICATION
  • FIRE PROTECTION
  • GEOTHERMAL | SOLAR THERMAL
  • PIPING | PLUMBING | PVF
  • PME COLUMNS
  • PME COLUMNS
  • Christoph Lohr: Strategic Plumbing Insights
  • David Dexter: Plumbing Talking Points
  • James Dipping: Engineer Viewpoints
  • John Seigenthaler: Renewable Heating Design
  • Lowell Manalo: Plumbing Essentials
  • Misty Guard: Guard on Compliance
  • RADIANT & HYDRONICS
  • RADIANT COMFORT REPORT
  • THE GLITCH & THE FIX
  • INSIGHTS
  • CODES
  • GREEN PLUMBING & MECHANICAL
  • PROJECT PROFILES
  • COLUMNS
  • SPONSOR INSIGHTS
  • COLUMNS
  • Codes Corner
  • Natalie Forster: Editorial Opinion
  • Guest Editorial
  • MEDIA
  • EBOOKS
  • PODCASTS
  • VIDEOS
  • WEBINARS
  • RESOURCES
  • INDUSTRY CALENDAR
  • DIRECTORIES
  • PM BOOKSTORE
  • CE CENTER
  • MARKET RESEARCH
  • CLASSIFIEDS
  • EMAGAZINE
  • EMAGAZINE
  • ARCHIVE ISSUES
  • CONTACT
  • ADVERTISE
  • PME EMAGAZINE ARCHIVES
search
cart
facebook instagram twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • PRODUCTS
    • FEATURED PRODUCTS
  • CONTRACTORS
    • BATH & KITCHEN PRO
    • BUSINESS MANAGEMENT
    • HIGH EFFICIENCY HOMES
    • TECHNOLOGY
    • WATER TREATMENT
    • PMC COLUMNS
      • Dave Yates: Contractor’s Corner
      • John Siegenthaler: Hydronics Workshop
      • Kenny Chapman: The Blue Collar Coach
      • Matt Michel: Service Plumbing Pros
      • Scott Secor: Heating Perceptions
  • ENGINEERS
    • CONTINUING EDUCATION
    • DECARBONIZATION | ELECTRIFICATION
    • FIRE PROTECTION
    • GEOTHERMAL | SOLAR THERMAL
    • PIPING | PLUMBING | PVF
    • PME COLUMNS
      • Christoph Lohr: Strategic Plumbing Insights
      • David Dexter: Plumbing Talking Points
      • James Dipping: Engineer Viewpoints
      • John Seigenthaler: Renewable Heating Design
      • Lowell Manalo: Plumbing Essentials
      • Misty Guard: Guard on Compliance
  • RADIANT & HYDRONICS
    • RADIANT COMFORT REPORT
    • THE GLITCH & THE FIX
  • INSIGHTS
    • CODES
    • GREEN PLUMBING & MECHANICAL
    • PROJECT PROFILES
    • COLUMNS
      • Codes Corner
      • Natalie Forster: Editorial Opinion
      • Guest Editorial
    • SPONSOR INSIGHTS
  • MEDIA
    • EBOOKS
    • PODCASTS
    • VIDEOS
    • WEBINARS
  • RESOURCES
    • INDUSTRY CALENDAR
    • DIRECTORIES
    • PM BOOKSTORE
    • CE CENTER
    • MARKET RESEARCH
    • CLASSIFIEDS
  • EMAGAZINE
    • EMAGAZINE
    • ARCHIVE ISSUES
    • CONTACT
    • ADVERTISE
    • PME EMAGAZINE ARCHIVES
  • SIGN UP!
Plumbing & Mechanical ContractorDave Yates: Contractor’s Corner

Contractor's Corner | Dave Yates

Wet vents: Take full advantage of the minimum standards set forth in plumbing code books

By Dave Yates
Example 1

Illustrations by Courtney Fathers / Plumbing & Mechanical

February 5, 2025

✕
Image in modal.

If you really want an honest, if not brutally frank, opinion: just ask professional plumbers! Every time I see the subject of using wet venting in an online plumbing forum, several keyboard warriors present themselves in full battle gear with a take-no-prisoners attitude. Visceral hatred for perceived shortcutting of “proper” venting boils over along with righteous indignation directed towards code bodies for allowing such nonsense.

Here’s where the rubber meets the road: if you’re bidding against another plumber who has a good grasp of the plumbing code and who utilizes and applies wet venting, while you remain committed to venting every single fixture, most likely you’re going to lose that bid. The wet vent plumber will use fewer materials and less labor for the same installation.

Example 2

Illustrations by Courtney Fathers / Plumbing & Mechanical

The plumbing inspector needs to be educated and up-to-speed with the codes they are enforcing, too. On the very first day as a township plumbing inspector, our bathroom remodel in the owner’s suite, with his and her bathrooms, we not only utilized a wet vent for his master bath, we also utilized a neat trick in order to avoid extending the new wet vent through the slate roof. An existing 3-inch vent pipe was just a few feet away and downhill from our lavatory dry-portion of the wet vent. Once more than 6-inches above the flood-level-rim of the sink, we simply turned the dry vent downward to run with the steep pitch of the roof, cut in a 3x2 wye (y pointing upward) to receive the 2-inch vent. Given that no belly/trap was created with both sides free to drain away any moisture/water, it was a code-approved venting method. Pity the poor plumbing inspector whose first real inspection included something he found very confusing. Saying he wanted time to think it over before passing our installation, he left the job. The drywaller called a day later asking if he could continue his work and the general contractor was pushing hard because he too had a schedule to maintain. I called the plumbing inspector who said he was not going to approve the installation! I asked him to get out his code book and together we read through the code passage several times. I strongly suggest you spend the extra money on the plumbing code commentary edition because after each code rule, there follows an interpretation regarding how that is to be enforced and why. The inspector still did not understand the installation and simply could not grasp the fundamental issue of airflow within the vent piping. When I noted this was a method taught to us during plumbing night school by the same instructor he had, he relented and passed the work. I’ll add that, as time passed, he became one of the best most knowledgeable plumbing inspectors in our area.

What is the primary purpose of properly sized and installed plumbing venting? To protect the minimum 2-inch deep trap seal and in order to do that, pressure and/or vacuum must not exceed 1-inch of water column. Pressure can be exerted against the trap seal by the slug of air being pushed ahead of a sudden larger flow, like when a toilet is flushed, or even by wind as it travels across a roof vent. The roof itself can cause lift forces, the same forces that cause planes to fly, and you have probably observed water in a toilet bowl rocking back and forth when it’s windy outdoors.


If you’re bidding against another plumber who has a good grasp of the plumbing code and who utilizes and applies wet venting, while you remain committed to venting every single fixture, most likely you’re going to lose that bid.


Sizing matters! In my area (Southeastern Pennsylvania), the code accepted by our AHJ (authority having jurisdiction) is the IPC (International Plumbing Code). Starting with the fixture vent, maximum distance from the trap to the vent is 5-feet for 1.25-inch, 6-feet for 1.5-inch, and 8-feet for 2-inch at 1/4-inch of fall per foot in the direction of flow.

Next up for consideration is the DFU (drainage fixture load) of the fixture draining into the wet vent for the bathroom group. A single lavatory sink with a 1.25-inch outlet is rated at 1-DFU. You can use a 1.5-inch dry vent rated for 1-DFU, which can continue as the wet vent for a single bathroom group with a maximum of one upstream fixture draining into the horizontal wet vent before finally joining the water closet drainage line. The branch drain from the water closet serving the balance of connected fixtures is sized according to the connected DFU load. A standard bathtub is rated at 2-DFU, however, showers, especially spa-like showers with multiple wands, heads, and body sprays is rated based upon total flow rates and range from 2- to 6-DFU. The IPC Table 709.2 dictates horizontal fixture drain size based on DFU load.

Read more from
Dave Yates ⮞

If we calculate the drainage sizing for a shower at 3-DFU (uses 5.7- to 12.3 gpm), we can still utilize a 2-inch trap and drain line. The 2 x 1.5-inch wye needs its branch to be rolled on an angle (see illustration) so that free airflow can be maintained for the wet vent.

How far can we run our 1.5-inch dry vent serving this bathroom group? Totaling up our DFU load: 1.28-GPF toilet = 3-DFU. The shower = 3-DFU. Lavatory = 1-DFU for a total of 7-DFU. IPC Table 906.1 indicates we must stay within 150 feet developed length. 906.3 states the developed length is measured from the farthest connection to the drainage system (you could argue that is from the 2 x 1.5-inch wye or starting where the dry vent begins at the 1.5-inch sanitary tee serving the lavatory sink to where it either joins a vent stack or to its termination above the roof.

Take full advantage of the minimum standards as set forth in our plumbing codes books in order to carefully redesign and install fully code-compliant DWV rather than blindly following the often outdated templates utilized by architects. You can successfully capture more jobs than your competitors by developing a thorough knowledge of DWV code-compliant installations. Wet venting codes really don’t differ greatly between the various code bodies. If you don’t mind investing a few extra dollars, get commentary editions of other codes as well because others, like NSPC (National Standard Plumbing Code), have far more detailed illustrations and if you’re like me, visual learning is understood and retained more easily. For example: NSPC Figures 12.2.1 – A and B illustrate quite graphically how positive and negative pressure forces affect the 2-inch trap seal.

KEYWORDS: HVAC contractors plumbers and pipefitters plumbing contractors safety weather

Share This Story

Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!

Dave yates

Dave Yates began his career in the PHCP-PVF trades in 1972 with F. W. Behler, a third-generation plumbing/ HVAC firm he purchased in 1985. Besides running F.W. Behler, writing articles for industry trade publications and speaking at events, Yates also is an experienced teacher in the hydronics industry, serving as an adjunct professor and on the Technical Advisory Board for the Thaddeus Stevens College of Technology. He can be reached at dyates@consultyates.com.

Recommended Content

JOIN TODAY
to unlock your recommendations.

Already have an account? Sign In

  • Worker using the Milwaukee Tool SWITCH PACK drain cleaner

    Pipeline profits: Drain cleaning, pipe inspection create opportunities

    Drain cleaning and inspection services offer lucrative...
    Plumbing News
    By: Nicole Krawcke
  • Uponor employee, Arturo Moreno

    The reinvestment in American manufacturing and training

    Plumbing & Mechanical Chief Editor Nicole Krawcke and...
    Plumbing News
    By: Nicole Krawcke and Natalie Forster
  • March 2024 Women in Plumbing hero image of woman engineer overlayed by circle of hexagon shapes with numbers from 1 to 10

    Celebrating 10 Influential Women in the Plumbing Industry

    Celebrating Women's History Month and Women in...
    Plumbing News
    By: Nicole Krawcke
Manage My Account
  • eNewsletters
  • Online Registration
  • Subscription Customer Service
  • eMagazine
  • Manage My Preferences

Bell & Gossett Illustrates Path to Net-zero at AHR Expo

Bell & Gossett Illustrates Path to Net-zero at AHR Expo

AI can boost efficiency and profitability for plumbing, HVAC contractors

AI can boost efficiency and profitability for plumbing, HVAC contractors

IPEX celebrates grand opening of new Florida distribution center

IPEX celebrates grand opening of new Florida distribution center

NIBCO Press Solutions

NIBCO Press Solutions

More Videos

Sponsored Content

Sponsored Content is a special paid section where industry companies provide high quality, objective, non-commercial content around topics of interest to the Plumbing & Mechanical audience. All Sponsored Content is supplied by the advertising company and any opinions expressed in this article are those of the author and not necessarily reflect the views of Plumbing & Mechanical or its parent company, BNP Media. Interested in participating in our Sponsored Content section? Contact your local rep!

close
  • J.J. Keller CMV vehicles on road
    Sponsored byJ. J. Keller & Associates, Inc.

    The dash cam game-changer for small business safety

Popular Stories

Integrate a heat pump with a boiler mounted on a brick wall.

How to integrate a heat pump with a boiler for dual temperature hydronic heating and cooling

Plumber using the DEWALT 20V MAX* Plastic Tubing Cutter to cut a white tube.

Making tough jobs easier: Most-used tools by plumbers in 2025

RCR Spring2025 Geothermal JHJ manifold-2

Geothermal and radiant: An energy-efficient powerhouse

Nominations for Plumbing & Mechanical's NextGen ALL-Stars are now open. Submit your nomination TODAY!

PM Aalberts August 14 Free Webinar: Precision Under Pressure: Optimizing System Performance Through Balancing and Air Removal

Events

November 13, 2024

Future Proofing MEP: Navigating the 2026 High Efficiency Water Heating Standards

Join our deep dive into DOE’s new standards so you can future-proof your MEP practice.

EARN: 0.1 ASPE CEU; 1 AIA LU/HSW; 0.1 IACET CEU*; 1 PDH

August 14, 2025

Precision Under Pressure: Optimizing System Performance Through Balancing and Air Removal

We’ll cover how proper air separation and hydronic balancing help maximize operational efficiency, reduce maintenance and minimize downtime.

View All Submit An Event

Poll

Will business be up or down in 2025?

Do you anticipate business in 2025 to be up or down in comparison to 2024?
View Results Poll Archive

Products

The Water Came To A Stop

The Water Came To A Stop

See More Products

2025 Bath & Kitchen Pro eBook

Related Articles

  • Repairing old faucets

    Dave Yates: Take a seat

    See More
  • Dave Yates performs backflow testing

    Backflow prevention: The last line of defense for plumbing system safety

    See More
  • Close-up View Of Open Dishwasher With Kitchen Utensils In It

    The evolution of dishwashers

    See More

Related Products

See More Products
  • building-code.gif

    Significant Changes to the International Building Code 2015 Edition

See More Products

Events

View AllSubmit An Event
  • November 13, 2024

    Future Proofing MEP: Navigating the 2026 High Efficiency Water Heating Standards

    Join our deep dive into DOE’s new standards so you can future-proof your MEP practice. EARN: 0.1 ASPE CEU; 1 AIA LU/HSW; 0.1 IACET CEU*; 1 PDH
View AllSubmit An Event
×

Keep your content unclogged with our newsletters!

Stay in the know on the latest plumbing & piping industry trends.

JOIN TODAY!
  • RESOURCES
    • Advertise
    • Contact Us
    • Directories
    • Store
    • Want More
    • Supply House Times
  • SIGN UP TODAY
    • Create Account
    • eMagazine
    • eNewsletter
    • Customer Service
    • Manage Preferences
  • SERVICES
    • Marketing Services
    • Reprints
    • Market Research
    • List Rental
    • Survey/Respondent Access
  • STAY CONNECTED
    • LinkedIn
    • Facebook
    • Instagram
    • YouTube
    • X (Twitter)
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2025. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing

search
cart
facebook instagram twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • PRODUCTS
    • FEATURED PRODUCTS
  • CONTRACTORS
    • BATH & KITCHEN PRO
    • BUSINESS MANAGEMENT
    • HIGH EFFICIENCY HOMES
    • TECHNOLOGY
    • WATER TREATMENT
    • PMC COLUMNS
      • Dave Yates: Contractor’s Corner
      • John Siegenthaler: Hydronics Workshop
      • Kenny Chapman: The Blue Collar Coach
      • Matt Michel: Service Plumbing Pros
      • Scott Secor: Heating Perceptions
  • ENGINEERS
    • CONTINUING EDUCATION
    • DECARBONIZATION | ELECTRIFICATION
    • FIRE PROTECTION
    • GEOTHERMAL | SOLAR THERMAL
    • PIPING | PLUMBING | PVF
    • PME COLUMNS
      • Christoph Lohr: Strategic Plumbing Insights
      • David Dexter: Plumbing Talking Points
      • James Dipping: Engineer Viewpoints
      • John Seigenthaler: Renewable Heating Design
      • Lowell Manalo: Plumbing Essentials
      • Misty Guard: Guard on Compliance
  • RADIANT & HYDRONICS
    • RADIANT COMFORT REPORT
    • THE GLITCH & THE FIX
  • INSIGHTS
    • CODES
    • GREEN PLUMBING & MECHANICAL
    • PROJECT PROFILES
    • COLUMNS
      • Codes Corner
      • Natalie Forster: Editorial Opinion
      • Guest Editorial
    • SPONSOR INSIGHTS
  • MEDIA
    • EBOOKS
    • PODCASTS
    • VIDEOS
    • WEBINARS
  • RESOURCES
    • INDUSTRY CALENDAR
    • DIRECTORIES
    • PM BOOKSTORE
    • CE CENTER
    • MARKET RESEARCH
    • CLASSIFIEDS
  • EMAGAZINE
    • EMAGAZINE
    • ARCHIVE ISSUES
    • CONTACT
    • ADVERTISE
    • PME EMAGAZINE ARCHIVES
  • SIGN UP!