Thread: Smell from Crawlspace

The original part of our house is ~850 sf and is on a crawlspace foundation with 6 vents plus a crawl-in entry in the garage. There is no moisture barrier in the crawlspace. There is an addition on a raised slab at the back of the house. The lot slopes up toward the back, and there's a steep hill behind our lot.

In 2003, we started to notice a bad smell in our house when we used a lot of water (like showering and then running the washing machine, which is in the addition), and the problem was worse after we had rain. The smell is always the worst in the addition and in the bathroom (these are adjacent). Since this started happening, we've had several plumbers come out. They have done things that seemed to fix the problem, like cleaning out the main drain line from the house and replacing pipes, but the smell would always come back after a year or two. Last spring, there was a large (10x10 ft) puddle of stagnant water under the house, and a cast iron drain pipe from the kitchen was sitting in the water. The plumber replaced the pipe, the smell went away, and we thought we finally had the problem fixed.

But in the last two weeks we've started to notice the smell again. I'm starting to wonder if the problem might be a combination of bad plumbing in the addition plus runoff water collecting under the house. None of the plumbers have been able to explain why the smell would be worse after we use water in the bathroom or in the addition. Who should I call to evaluate this problem? Do you have any ideas about the cause and possible fixes?

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In my opinion you should have the waste lines inspected with a camera.

I agree with Ray...
Also wet clay smells like a sewer or dead animals depending on your sense of smell and the type of clay. If the exposed space consists of clay this can add to the problem. Add a vapor barrier.

I agree with the use of the camera, but also look into the location of any septic systems on, or bordering your property. Water from a septic will not smell very nice.

I agee with the others but would also add a pressure test of both fresh water and especially the sewer. While the camera is great for finding a leak or problem it is not a fool proof as you might think. The pressure test will yield a pass or fail aspect. If the sewer does not hold pressure then you keep looking. Maybe do the pressure test first and be prepared to look further if it fails.

When we purchased our home, we had the same smell you are describing. It ended up just being the water sitting in our crawl and not moving. The smell was creeping thru the floor and into our home. We replaced our sump pump and made sure the water wasn't building up anymore and haven't had much of a problem since. Every once in a while when it rains really bad, we will get the smell a little bit...but once the pump kicks on and removes it, we are all good to go again. Maybe you could look into a home cleaner to help eliminate the smell. Has anyone looked into a angie's list house cleaner before?

Originally Posted by Okie Homeowner

The original part of our house is ~850 sf and is on a crawlspace foundation with 6 vents plus a crawl-in entry in the garage. There is no moisture barrier in the crawlspace. There is an addition on a raised slab at the back of the house. The lot slopes up toward the back, and there's a steep hill behind our lot.

In 2003, we started to notice a bad smell in our house when we used a lot of water (like showering and then running the washing machine, which is in the addition), and the problem was worse after we had rain. The smell is always the worst in the addition and in the bathroom (these are adjacent). Since this started happening, we've had several plumbers come out. They have done things that seemed to fix the problem, like cleaning out the main drain line from the house and replacing pipes, but the smell would always come back after a year or two. Last spring, there was a large (10x10 ft) puddle of stagnant water under the house, and a cast iron drain pipe from the kitchen was sitting in the water. The plumber replaced the pipe, the smell went away, and we thought we finally had the problem fixed.

But in the last two weeks we've started to notice the smell again. I'm starting to wonder if the problem might be a combination of bad plumbing in the addition plus runoff water collecting under the house. None of the plumbers have been able to explain why the smell would be worse after we use water in the bathroom or in the addition. Who should I call to evaluate this problem? Do you have any ideas about the cause and possible fixes?

A hydrostatic pressure test would be a good way to check for any leaks,broken ,or poorly joined pipes. A smoke test of the system could determine if you have a vent that may not have been vented out or possibly broken . Could be sewer gas . If there are no problems with the drain system . check for areas where water may be seeping into crawlspace.

Have you checked your plumbing vents?

Camara inspection don't view the venting. Plumbing vents commonly rot out above the vent take off, (commonly in the walls) I've seen many just above the santee when it transitions to galvanized. Also check your wax ring connections at the water closets, during periods of excessive sewer use gas back pressure can be very high, your vents could also be inadequate.

Curious how they do a pressure test of sewer pipes.

Originally Posted by Jack Feldmann

Curious how they do a pressure test of sewer pipes.

It means going to Del taco and putting away a mocho combo w/el scorcho sauce. Then wait....

You might want to try a peppermint test which is much cheaper before spending money on cameras. Pour a fair amount of pure peppermint extract down the roof vent stack, then sniff around throughout the house for the peppermint odor. This may help locate a general area in which a vent is leaking. No smell of peppermint would likely indicate the plumbing is intact.

Another possibility is a neighbor discharging a washing machine outdoors or to a sump pump which then discharges to the surface. I've seen this and it does generate quite an odor.

Originally Posted by Steven Saville

You might want to try a peppermint test which is much cheaper before spending money on cameras. Pour a fair amount of pure peppermint extract down the roof vent stack, then sniff around throughout the house for the peppermint odor. This may help locate a general area in which a vent is leaking. No smell of peppermint would likely indicate the plumbing is intact.

Another possibility is a neighbor discharging a washing machine outdoors or to a sump pump which then discharges to the surface. I've seen this and it does generate quite an odor.

Peppermint smell is stronger than poop? Never would have guessed.