How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manfuactured and modular homes

Does a sink drain trap have to be plumb?

Sunday, November 1, 2020

"Traps shall be set level with respect to their water seals,” according to the International Residential Code (IRC P3201.3) and the Residential edition of the Florida Building Code (FBC). But the goofy angle of the trap shown above is only one of its problems. The trap is also installed backwards, creating an excessively tall trap seal, and the accordion-type piping makes the whole assembly guaranteed to clog. The trap shown at right is a much less egregious example, but needs to be correctly aligned with the tailpiece. 

    A plumbing trap must maintain enough water in it to prevent sewer gas from rising up into the house, but not so much that it creates a drain that is sluggish and easily clogged, and the interior surface of the pipe should be self-scouring. 

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Here’s links to a collection of some of our other blog posts about PLUMBING DRAINS AND TRAPS:

 Why is it a problem when a trap under a sink is installed backwards? 

What causes a gurgling sound when a bathtub or sink drains? 

What is a "combination waste and vent" in a plumbing system? 

• What types of plumbing traps are illegal by code?

• Why is garbage disposal not allowed at a combination waste and vent (CW&V) under a sink?

What is a building trap?  

• What is a double trap in plumbing? 

• Can two sinks share a trap? 

 Why is the European-style bottle trap not approved by the plumbing codes in the U.S.? 

What is an auto vent, air admittance valve, or check vent?

Can I make a trap under the sink from straight pipe and 90º elbows?  

If all the plumbing drains have water in them and you can still smell sewer gas, what's causing the problem?  

What is an "S-Trap" under my sink? Why is it a problem? 

What is a P-trap?

Is a sink required to have a drain stopper? 

• Can a laundry sink drain be installed without a trap under it? 

• What is a drum trap at a plumbing drain?

• Can a dishwasher drain hose be connected after the sink trap (to the trap arm)? 

• What is the minimum and maximum distance a P-trap can be below a sink? 

What is bell trap at a plumbing drain? 

     Visit our PLUMBING DRAINS AND TRAPS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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