The S-Trap

The purpose of a plumbing trap under a sink is to prevent odorous sewer gases from entering the house back through the sink and tub drains.

There are two basic types of traps: P and S configurations – both have a trap section, which is a U-shape pipe where water sits in the U and creates a water seal, so that sewer gases at the street sewer system can’t move past the water.


The modern P-trap discharges water through a horizontal pipe through a wall… Whereas, the S-trap shown in the photo discharges water vertically down towards the floor.

The problem with “S” traps is that fast draining water from a sink or bathtub may siphon out the water seal and allow sewer gas to enter the house.

Schedule an inspection – mention “I’d like a peace of mind inspection” – Save $25

Roof Ridge Rot

This was a 10 year-old, heavy-duty asphalt shingle roof in Danville with a 40-year warranty.

Provided it’s safe, home inspectors climb onto roofs to look at the conditions.

The roof field looked great, but every single roof ridge shingle was deteriorated. Why?

Before roof manufacturers manufactured roof ridge shingles, roofers would take a standard organic asphalt shingle – remove the tabs – fold the shingle back on itself and use it as a ridge shingle.

These organic shingles would last 6-10 years due to the sun’s UV rays drying out the shingles and making them brittle.

Using a newer fiberglass shingle in this manner proved to last much longer.

Schedule an inspection – mention “I’d like a peace of mind inspection” – Save $25

Retaining Wall Woes

A section of this Castro Valley property retaining wall was leaning.

The three most common signs of imminent retaining wall failure are leaning, cracking and bulging.

The main cause of retaining wall failure is poor drainage at base of the retaining wall and no weep holes

A secondary cause of failure is not having a deep retaining wall footing (the concrete base in the ground that the wall sits on)

Engineering talk – When water accumulates behind a retaining wall, it pushes on the wall with a lot of force hydrostatic (water) pressure – thus the leaning section of retaining wall in the photo.

Schedule an inspection – mention “I’d like a peace of mind inspection” – Save $25

Spitting Water

The House Whisperer checks dishwasher drain cycles and routinely finds 15% of dishwasher drain hoses are blocked with food sludge or are kinked.

This causes water to spray out of the air gap device. What’s an air gap device?

It’s a small cylindrical fixture with slots, that’s installed between the dishwasher and the kitchen sink drain pipe or garbage disposal.

It sits on the sink deck or the kitchen countertop and is designed to prevent dishwasher drain water from flowing backwards into the dishwasher – a good thing since food particle bacteria is present in the drain hose.

If water flows out an air gap device, it’s a red flag.

Usually, there’s food blockage at the garage disposer connection, the drain line is kinked, or the knockout plug in the garbage disposal wasn’t removed during installation.

Schedule an inspection – mention “I’d like a peace of mind inspection” – Save $25