• All about Roofing
    All about Roofing
  • Solid Deck-Framing Advice
    Solid Deck-Framing Advice
  • Remodeling in Action
    Remodeling in Action
  • Read FHB on Your iPad
    Read FHB on Your iPad
  • 7 Trim Carpentry Secrets
    7 Trim Carpentry Secrets
  • 9 Concrete Countertops Ideas
    9 Concrete Countertops Ideas
  • Video Series: Install a Rock-Solid Tile Floor
    Video Series: Install a Rock-Solid Tile Floor
  • Video: Build a curved step
    Video: Build a curved step
  • 7 Smart Kitchen Solutions
    7 Smart Kitchen Solutions
  • Basement Remodeling Tips
    Basement Remodeling Tips
  • Deck Design & Construction
    Deck Design & Construction
  • Video: Install a Fence
    Video: Install a Fence
  • Gallery: Custom Flooring
    Gallery: Custom Flooring
  • 12 Remodeling Secrets
    12 Remodeling Secrets
  • Magazine Departments
    Magazine Departments
  • Master Carpenter Videos
    Master Carpenter Videos
  • Clever daily tip in your inbox
    Clever daily tip in your inbox
  • Energy-Smart Details
    Energy-Smart Details
  • Tips & Techniques for Painting
    Tips & Techniques for Painting
  • 7 Small Bathroom Layouts
    7 Small Bathroom Layouts
Pin It

Build Like a Pro: Replace a Sink Trap

In this Build Like a Pro video, Bruce Norman explains how to rebuild your entire sink trap assembly and make it the best plumbing in the house.

Length: 6:39
Produced By: John Ross, Edited by Cari Delahanty

Sink traps may need replacement for a few different reasons. Because the undersink area is regularly used as storage, the exposed trap assembly is bumped and jostled, and can become damaged. Also, the trap assembly might not have been installed correctly, and its horizontal runs could be insufficiently pitched and not drain well. Finally, the trap could be an outdated configuration, such as an S-trap, which has been eliminated under most code jurisdictions. While some traps can be taken apart and cleaned to restore proper flow, I recommend rebuilding the entire trap assembly.

The two materials most often used for sink plumbing are PVC and ABS (acrylonirile butadiene styrene). For the repair featured here, I used ABS because the joints are bonded with one-part glue as opposed to the two-part glue needed for PVC. I use glued joints wherever possible but incorporate threaded unions at the trap and tailpieces for serviceability. For this sink, I added a cleanout below the trap assembly, which is required by code. Then I added the sanitary tee to allow for venting.

Originally, there was no vent to this old S-trap system, which is common for old plumbing. Most codes require the vent to be restored to allow liquid to drain quickly. In this case, I installed an air-admittance valve (AAV). Check with your local building department for any restrictions if you choose to use an AAV.

Read my article "Replace a Sink Trap" from Fine Homebuilding #206 for more details and photos on this process. And read about another technique for sink trap installation as well as Fine Homebuilding's primer on Better Undersink Plumbing.

John Ross

September 11, 2009