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posted: 3/3/2013 5:39 AM

Icy vent stack may be culprit in bathroom odor

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Q. A while back, you gave us advice about a problem with our tile installation. That was the best advice we were given, and it was very helpful.

Last winter, we started getting a sewage smell in the master bathroom of our 21-year-old home. We had not had this problem before. When the weather started getting nicer in the spring and summer, the smell went away. When we had the smell, it generally built up over the nighttime hours and went away when we turned on the water to shower each morning.

When the weather started getting colder again this fall/winter, the smell returned and is worse than ever. It smells like a sewage plant in that bathroom every morning. (We keep the bathroom door just about closed each night.) It seems to be worse when it is cold out. This bathroom has a shower stall, a separate tub (it is never used, but it's cleaned regularly and has water run through it), a toilet and two sinks.

Obviously, we called a plumber. He cleaned out our drain and recommended that we pour bleach down the drain every 90 days. (We had previously tried bleach and Drano on numerous occasions.)

We don't have an issue with the water draining properly -- it goes down fine. Following the plumber's visit, we still had the exact same problem with the sewage smell. It has gotten worse and worse this winter. So we called the plumber back and explained the problem. One of his several suggestions was to dry and cover the shower drain with duct tape overnight and see if we had the smell. We did that, and we did not have the smell in the morning. When we removed the tape, the smell was clearly in that drain, underneath the tape.

We followed all his other suggestions, and everything checked out fine.

At this point, the plumber says the smell is a "mystery" and he doesn't know what to do. He said all the things we did indicate the smell is coming from this drain, although he says that shouldn't be possible, because there is always water in there. He said the tests we did indicate there is proper venting. He basically said he'd have to come and start cutting up our walls.

As a stopgap measure, to avoid having this smell every morning, we have taken to placing a heavy item over the drain each night until we take our morning showers. We do not get the smell (until we remove the object), so it is obvious that the smell does come from that drain.

Obviously, we need to get this fixed. It is an awful smell, and it may be a health risk. There has to be a reason and a solution for this problem.

We do not know where to turn. We don't even know what kind of professional to seek out. Should we call another plumber? Do we need to have someone go up on our roof to check the vent? If you can advise us in anyway, we would be so appreciative!

A. Your plumber's suggestions (most of them deleted because of their length) were on target. The source of the smell is a mystery, but I am zeroing in on the vent stack.

You haven't told me where you live, but I assume, from your comments, that you are in a cold region. If the plumbing stack through the roof is narrower than 3 inches, it is possible it ices up completely. On cold nights when the stack effect in the house is greater because of the temperature differential between indoors and out, if the vent stack were iced shut, sewer gases could be drawn into the bathroom to equalize the negative pressure created by the stack effect. More than likely this would be through the base of the toilet, although your experiments indicate it is through the shower drain, which is most unusual if the trap is full.

When you shower, the hot water may melt the ice at the top of the vent stack, allowing the venting system to function, albeit slowly. But as soon as it ices and seals up again, the scenario is reset. Have you heard any whistling sound after you shower, as air flows through the small opening until it freezes shut again?

I suggest you have the roof stack checked by someone who is competent to do so. If it is less than 3 inches, consider having it replaced from the floor of the attic through the roof with a larger one -- 3 to 4 inches in diameter.

I admit this is a wild guess, but it is all that makes sense at this time.

Q. Someone told me there is a porous concrete that is ideal for driveways because water and melting snow go through it and do not run down the street. Have you heard of this, and is it something you'd recommend?

A. Although pervious concrete is an environmentally friendly choice, it is expensive. It is not appropriate for cold regions, because once the ground freezes, any water percolating through the concrete cannot be absorbed by the substrate. It freezes and can cause serious damage to the concrete.

Q. The city replaced a valve on our street, and I got muddy water in my water heater tank. I keep draining from the valve at the bottom of the tank but cannot get out all the muddy water and sludge. Can I do anything besides get a new water tank?

A. Turn off the power to the heater and keep draining it until the water clears up. It should eventually do so.

Q. I am considering installing a water softener in our 1830s farmhouse. I have done considerable reading online, and it seems the only true "softeners" involve the use of sodium.

Do you have any experience with salt-free softeners, which apparently aren't so much softeners as descalers? Do these work? Any help or information you could provide would be greatly appreciated.

A. The best advice I can give you is to have your water tested, as the appropriate softening system to use depends entirely on what a water analysis reveals. Look for a Kinetico dealer in your area; I have had good experiences with the company over the years.

There are salt-free systems that use potassium-based pellets, but they cost four times as much as sodium-based pellets. The amount of sodium per grain of hardness is small, so you may decide that the difference in cost between potassium- and sodium-based pellets is too much.

Q. Our home is 7 years old and is almost surrounded by an apple orchard. We knew we would probably see more bees here than at our last home because of the orchard.

When we moved in, our basement was unfinished, just framed off, and had blanket insulation. We have a sliding-glass door at the back of the basement and three windows in front. We noticed lots of yellow jackets and hornets around the house. Then we began to get visits from them, but just in this basement area of the house.

My husband sprayed around outside and also sprayed the track of the slider, because that is where we would mostly start to see them. We kept having the problem and had an exterminator out three times. The bees would be gone for a little while but always came back.

About two years ago, we were able to finish off the area and hoped this would finally fix the problem. This is where my grandchildren play. We are now toward the end of January, and we still find a hornet or yellow jacket, but mostly hornets, every week or so. And there are dead ones in the track of the slider where my husband has continued to spray. We can't see where they come from; they just seem to appear. We have filled any openings that were found outside, but there really wasn't anything.

Would you have any ideas for us? Do we have a nest someplace in that finished basement?

A. I doubt you have a nest inside the house, because it would be very active in warm weather and you would be able to see it. Yellow jackets and wasps do not need much of an opening to get inside, so I suggest you look critically around the outside of your basement.

Since you have found them in the track to the sliding door, I suggest you keep spraying it, as it sounds as if the weather stripping is not completely effective.

If you have a deck on the main floor with cantilevered joists or a roof with projecting beams, caulk the joints of the joists and beams with the surrounding material. As wood shrinks, small cracks open up, which are great sources of insect invasion.

Interesting follow-up: "I read today your solution to the mold problem in the ICF house and thought I might comment, as I also live in an ICF house in Charlotte, Vt. I agree this particular house may not have enough insulation; however, it may also not have left enough ventilation room around the refrigerator as some require. Most refrigerators have condensation water that they need to vaporize or drain. Those that vaporize it need clear ventilation space to keep the air from saturating and thus creating mold conditions. I suggest this may have been a part of the problem.

• Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. Write to him in care of the Daily Herald, P.O. Box 280, Arlington Heights, IL 60006, or via email at

2012, United Feature Syndicate Inc.

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