Cast iron drain pipes leak under a basement floor:

This article describes Conrad's experience in tracking down a sewer gas odor that appeared in the building's (transite) heating ducts, finding a leaky sewer pipe under the basement floor, and repairing (or replacing) the in-floor cast iron plumbing drain waste vent piping, piping materials.

Cast Iron Drain Pipe Leak & Repair Case - Odors Lead to Discovery of Under-Floor Drain Leaks

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Leaky Cast Iron Drain Pipes Under a Floor Slab Send Sewer Gases into HVAC Ducts

A reader (Conrad) provided us with the photographs and case history of the successful track-down of sewer gas odors in a building (SEWER GAS ODORS). The case began with a complaint of sewer gas odors in the building's heating duct work system. As you can see from the "before" and "after" photos, this case involved the following combination of circumstances:

• A transite heating duct was buried in a basement floor (below the slab) and located parallel to and immediately above a cast iron sewer pipe (photo below left)
• The sewer pipe deteriorated and developed leaks (photo below right)
• The transite (asbestos cement -
  
  see TRANSITE PIPE AIR DUCT ASBESTOS RISKS) air duct was also leaky
• Sewer gases leaked out of the cast iron waste line and into the heating duct line.
• The repair required breaking up the concrete floor slab and replacing the leaky sewer line. We recommended replacement of the transite heating duct as well.

Photographs of Finding, Excavating & Diagnosing Transite Duct & Cast Iron Drains Buried Under the Basement Slab

The photo at below left shows the basement floor slab cut open to permit replacement of the leaky cast iron drain line. At below right our final photograph shows the new white PVC drain piping installed in the floor.

Photos of Repairs to the Leaky Cast Iron in-Slab Drain Lines

At above right and in more photographs below we show the sewer line break repairs and floor re-tiled kindly sent along by reader Conrad.

Also see CAST IRON DRAIN PIPING. Other types of building piping systems are discussed at GAS PIPING, VALVES, CONTROLS and at OIL TANK PIPING DEFECTS. or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question:

(Apr 13, 2015) Nancy said:
Hello and so glad I found your site!
I bought my house 3 years ago and it had an odor then--(45 years old,single story on foundation.) We demoed everything and still have the odor. The laundry room has a floor drain, and at the time I thought "how cool". When I retiled the floor I kept the drain. Only appliance now is a washer/dryer in this room, along with a sink. Wish I had sealed over the drain (is this even possible?)
Anyway, people always comment on the odor......smells like sewage. My husband and I are here all the time so I think we are now used to odor. I'm more sensitive and notice it more. My brother said he thought it could be the trap and gases. I've put water down it as well as Dymon-Liqued Alive.
I saw the pictures of drains being ripped out of foundation and do no want to go to that expense. This laundry room sits next to a powder room with sink and toilet, but I cannot imagine they would share the same drain.
What are your suggestions? Mineral oil? Seal drain? and what with?
Help,
San Antonio Stinky

Reply:

Nancy:

First there are some simple things you can try:

Pour clean mineral oil into the floor drain trap so that it's not "dry" - see if that stops the odor.

It's also simple to duct-tape a flat rubber tub drain cover over the floor drain.

Both of these are stop-gap measures: we don't want potentially dangerous methane to be leaking into a building.

Before abandoning the drain by pouring concrete into it I'd be sure that you are not risking blocking a drain inlet connection from some other plumbing fixture nearby.

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Continue reading  at CAST IRON DRAIN PIPING or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• BACKUP PREVENTION, SEWER LINE
• BLOCKED DRAIN REPAIR
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CAST IRON DRAIN LEAK, ODOR, REPAIR at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to PLUMBING SYSTEMS

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