Strong unbearable chemical smell in bathroom (2023 Update)

[Thomas]

Is there anything outside that might be sucked inside when the exhaust fan is on? If the bathroom is good, look elsewhere. There is always an answer. Plastic film on a light?

[rbowman]

Do you mean the acetic acid smell that some RTV compounds produce during curing? Are they using vinegar for anything? There is a bacterial tree infection called wetwood that gives off a vinegar smell but I don't think it affects seasoned wood like dry rot.

[Peter]

Is there any place you might have missed during renovation that could be moldy? I've noticed the uncured caulk vinegar-like odor you describe when I've encountered moldy rugs, towels, etc.

[build.austin]

Thx for replies. It is not moldy, or septic, or vinegar. I can confirm the smell is coming from the shower P trap (2" pvc, in concrete slab). The smell is exactly like wet fiberglass that hasn't cured yet. The Ptrap is not clogged (ten gallons from buckets drain smoothly and quickly), and the Ptrap does hold water properly. During renovation, a custom fiberglass shower pan was built by a contractor - that smelled horrible for a couple days, then cleared up, which is typical for fiberglass work. BUT the Ptrap still smells like fiberglass, and it's been several months. I've never heard of fiberglass failing to cure, but that's my best guess now. Thoughts?

[SJ]

We've ripped out a bathroom due to smell, so I know the frustration w/ trying to figure it out. Could it be the pvc cement in the Ptrap? Our issue was Durock. And with the new bathroom the smell of the wall grout was strong for a while, probably still is but I don't shut the door often to let it accumulate. Let us know if you figure it out.

[Shawna Harty]

Hi Everyone. I see many people are experiencing similar things. We just built a house and moved in 6 months ago. Two bathrooms that share a wall have this "wet cement/chemical" smell in them. When we close the bathroom doors, the smell gets worse. I have ran the exhaust fan, opened the windows, hired plumbers to check for sewer gas, and have done multiple smoke tests. We have also done mold testing, which was negative. We cannot find the culprit. I am convinced it has something to do with the durock. I can smell the strong odor coming from the shower faucet handle and an outlet located on the same wall. The durock was waterproofed as well. Even though the bathrooms share a wall, one bathroom smells significantly stronger than the other. I wish someone can find the root cause. I feel like it is making my family sick that is exposed to the smell most often. Our other bathrooms that also have durock do not have the same problem though. Please help!!!

[SJ]

The other bathrooms you mention that also have durock that don't have same problem - was it the same batch of durock used in these bathrooms, or was it durock from a long time back? If so, perhaps the product was changed in recent years and the newer stuff has this issue. Can't understand how if all the same recent Durock, how 2 bathrs would smell and the others not. How odd. I've smelled the stuff and can't stand being anywhere near it.

[Meat5000]

My guess is that septic tank flue is blocked so chemical fumes of tank additives are coming back up the toilet when pressure builds up.

[Meat5000]

Oops think I replied in wrong place. Im guessing your septic tank flue is blocked and when pressure builds up gasses are coming out of the loo and shower trap if it's connected. Did you put a U-bend in the shower outflow?

[build.austin]

Following up: We waited until April, fully SIX months since the work was completed, and client demanded that I start demolition because the smell was still intermittently present, and BAD when there at all. I insisted on doing the demo incrementally, to help isolate what might be causing the smell. So I demo'd the shower floor tile and mortar bed to expose the fiberglass pan- smell still present. I destroyed and removed the fiberglass shower pan and the bottom 2' of tile/cement board down to bare studs- smell still present. I removed all the shower walls and bat insulation of the entire shower- smell still present. Now there's no shower, nothing, and it still intermittently stinks.

So then she insists that I demo the vanity cabinet (it had been removed during the original mold remediation and I had re-assembled it and installed it last October. Smell goes away. No smell since approximately May of this year. Four months, gutted bathroom, no smell. She asks me to reinstall the vanity/sink for guest use at an upcoming party, and I do it, for free. Smell returns. 10% as strong as before, but definitely back. Intermittent, same as before.

So am I on the hook for this smell? Do I owe her rebuilding a new shower for free, as she claims? It's been a year and I honestly feel horrible for her, she has not moved in to the house yet because this would be her son's bathroom and he can't tolerate whatever this smell is. But I'm confident it wasn't caused by my work.

[Retirednoguilt]

Are you on the hook? I recommend a consultation with a lawyer who specializes in this type of situation.

[Dean Hoffman]

Who bought the vanity? Retirednoguilt has good advice.

[Ed Samson]

I can't speak to liability but I'll say this about the odor. Most sinks have an overflow hole, meaning the sink is double-walled. That space fills with hair and soap and develops mold. I suspect the bad odor comes from that area. When dry it doesn't have much odor but, when wet, the mold and odor reactivate. That area is difficult to clean but can be partially accessed by removing the drain assembly. Bleach through the overflow may help as well.

[RJH]

Any cavity walls or capped/unventilated chimneys?