S-Traps vs P-Traps

S-Traps vs P-Traps

S-traps-vs-P-traps, S-traps are no longer allowed in new construction


S-traps vs p-traps were common Years ago however most plumbing codes have banned S-trap configurations in favor of P-trap style fixtures. S-traps are no longer used in modern plumbing because on rare occasions with just the right conditions the water can be sucked out of the trap allowing sewer gas to enter your home.

The risk from sewer gas can be much worse than just that terrible smell. Sewer gases can be poisonous or even explosive and are not to be treated lightly.

S-trap failure

S-traps vs p-traps are obsolete and may need to be replaced

requires a large amount of water to flow quickly past the trap. This is usually caused by allowing a sink full of water to drain rapidly. The easy fix is to always refill the trap with water after using the sink.

Plumbing codes, however do not allow for common sense fixes, they are designed to makes things work as predictably as possible. Years ago most plumbing codes banned S-trap configurations in favor of P-trap style fixtures. S-trap fixtures are most often found in older homes and homes  remodeled by do-it-yourselfers .

On the other hand if your house does have S-traps it is not a major concern, most people will never experience a sewer gas smell. The perfect solution would be to tear out the wall and install a vent stack that would go through the roof.

Luckily there are three other things you can do:
• It is probably OK to do nothing as long as you do not have a problem
• You can install an Auto Air Vent (AAV)
• You can modify an S-trap to work similar to a P-trap

Here are two possible solutions for s-traps

The AAV is usually frowned on by most plumbing codes but may be the only answer short of tearing out the walls and ceilings to run a vent through the roof.

Many different styles of AAV are available starting at $10 and S-trap to P-trap conversion kits are available from hardware and home improvement stores for $30 TO $40. Please note, proper stack venting is always preferred to alternate methods when possible.

Another solution is to change the s-trap

to a modified p-trap by extending the trap arm to a maximum of 2 1/2 time the diameter of the drain line (3 1/4″  for 1 1/4 and 3 3/4″ for 1 1/2 drain lines).  Neither fix is allowed by most plumbing codes for new construction.  The alternative however is much more palatable than tearing out the wall and busting a hole in the roof for a proper vent.

a modified P-trap is a better solution

Properly maintained s-traps do not necessarily need to be replaced, however there are acceptable solutions should you experience sewer gas odors.

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Plumbing problems found at inspections

Plumbing problems found at inspections

Plumbing  Problems are Often Easy to Repair

(HawleyHomeInspectionsLLC.com) Plumbing repairs called out in a home inspection are usually minor.  However occasionally we find problems that must be repaired.  These are usually do-it-yourself projects gone terribly wrong.

Many plumbing repair problems can easily be addressed by a handy man or a proficient do-it-your-selfer.  Other problems such as a replacing a sewer main should only be addressed by a licensed plumber.

Some of the more common plumbing problems we find are;

  • leaking faucets
  • garbage disposals that leak
  • garbage disposals that are not working
  • leaks in pipes under the sink or vanity
  • low water pressure
  • slow flowing drains
  • outside faucets that leak under pressure
  • clogged drains and traps
  • hot and cold water lines installed backwards
  • tub/shower controls installed backwards

As we move through the inspection process we will note;

  • any improper repairs to water pipes or drain pipes
  • inoperative sump pumps
  • missing or improper extensions of the pressure relief valve on the hot water heater
  • missing expansion tanks on the hot water heater (not enforced in all areas)
  • check for leaks in the water or drain lines
  • slow moving drains
  • any other normal and customary deficiencies

Here are a few of the most common plumbing problems we find:

Duct tape was a wonderful invention but really does not belong in a plumber’s tool box very often.

This is neither proper use of duct tape or proper plumbing practice.

A close second to duct tape abuse is the use of black vinyl electrical tape to “cure” leaking drain pipes.

The proper fix is usually not much harder than the imaginary fix often used by do-it-yourself plumbers.  Some leaks require no more than tightening a loose fixture nut or other simple no tool fixes.

Occasionally we find an outside faucet that has frozen and burst.

Remember if you leave your garden hose connected the water may not drain properly. A good cold snap can spell disaster when you turn your faucet on in the spring.  Even a “freeze proof” hose bib will freeze if a hose is left connected and the water can not drain properly.

Properly installed plumbing is no match for the well intended Saturday afternoon plumber.  Plumbers in our area have to be licensed and complete a four year apprenticeship.   Some projects are best left to the experts with the proper training and tools.

Seemingly harmless openings in the sewer drain may allow harmful sewer gases to enter the home.  All vent and drains should be properly sealed.

Many times we will find plumbing vents that are blocked or do not exit the home.  Occasionally we will find one or more vents that terminate in the attic,  All vents should vent to the outside and clear the roof by a minimum of twelve inches.  Short vents can be added to in order to meet the minimum height.  Although proper this is not considered to be a major deficiency.