Old house/attic smells


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Old 07-28-23, 06:22 AM
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Old house/attic smells

New here and have spent a couple of hours reading the forum. Wish we had found this 3 years ago! We completed a remodel of a house built in 1967 last fall. Tri-level house. First floor is over basement, 2nd floor and part of 1st floor on concrete slab. We are the 3rd owners, almost everything was original (stove, bathrooms, ect). Last owner owned for 30 years and left almost everything original, they did add a 2nd level HVAC system. Which last year as we wrapped up the remodeling it crapped out and we had to replace it. In both attics there is vermiculite and old insulation and a decision I think that will haunt us was made to leave it be. Once we were done with construction we had the air ducts cleaned. Itís was awful. Looked like piles of kittens were pulled out. During the remodel we discovered we had no attic ventilation. When they had the house re-sided they closed off the soffits as well missing some other needed ventilation.. So part of the work was to open that back up and that happened when we had it re-sided last fall. In some cases we had new duct lines run on the 2nd floor as part of the remodel. During the duct cleaning we asked for them to verify there were no leaks in the ductwork because I was still smelling old hot attic, they said they didnít see evidence of leaks. So after all of that, Iím sooo disappointed that when it gets hot and the upstairs unit kicks on, the smell is horrible. For a lot of people they donít seem to get as bothered by it, Iíve been told I have a strong sense of smell. It makes me want to move everyday I smell the hvac system kicking in. The brand new bathroom fan even seems to draw the smell in during warmest days. (Which this house didnít have bathroom exhaust systems previously). Aside from wishing a storm would rip the roof off and vacuum out the attic, what can we do? My husband has wanted an attic fan but has been told by 2 other hvac companies that all the work done with baffles (?) and opening back up the soffits we donít need one. I keep thinking it would exhaust all the old smell away, but then I think Iím stuck with the smell till we empty out the old insulation and replace any duct lines that are not new. One other note, the 2nd level attic has very little space to move around, both hvac and electricians had issue dealing with working in the space. (And somehow our working doorbell no longer worked after all the work, and it runs through the 2nd floor attic). Any help in solutions would be much appreciated.
 
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Old 07-28-23, 08:01 AM
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Jrjka - Welcome to the DIY forums!

You may indeed have a strong sense of smell, but generally an older house of 50+ years old will often take-on a stale, musty scent. Poor airflow, high humidity, dirty air ducts, closed-up spaces including attic or basement areas and just general lack of keeping 'things' clean, orderly, organized and updated all add to producing that gross smell you detest. If damp, exposed dirt is also part of the equation, it just makes things even worse.

Unfortunately, this smell you are so opposed to has certainly seeped into flooring, structural wood like floor joists, wall studs, walls, floors, ceilings, etc, etc. It's just going to be next to impossible to get rid of it without a thorough cleaning and disinfecting - something you almost certainly will have to call in professionals to do for you. Even then, you'll probably never totally believe the smell is really gone - that is, unless a professional takes care of it like it's a mold or biohazard cleanup situation.

You certainly don't want to just mask or abate
the odor - that would be a huge mistake that most people would likely make - trying to actually cover the smell up. You want whatever is causing the smell to be it eliminated.

Sadly, I do not think there is anything you can do yourself that would really satisfy you (mentally and smell-wise). I would recommend bringing in a professional - one that does mold and biohazard remediation for example - to evaluate your matter.
 

Last edited by Kooter; 07-28-23 at 08:36 AM. Reason: orthography
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Old 07-28-23, 08:25 AM
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One option is to consider ozone. In order to be effective it must be in very high concentrations so you would have to leave the house for treatment. There are professionals that offer treatments or you can buy or make your own ozone generator but most often when I've seen people DIY they just go too light and don't see much benefit.

I have a pretty large generator and will seal off one room and let the generator run in it for 3 or 4 hours. Then I let the room remain sealed and don't go back until the following day. Air out the house and move the generator to another room and treat it. It's a slow process but it can get rid of many organic based odors. If you attempt this yourself do some studying so you understand how ozone works and it's hazards. Go into a room that's being treated and you'll feel like you've been tear gassed.
 
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Old 07-28-23, 09:06 AM
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Contractors put an ozone generator in our attic after a fire. It removed all of the smoke smell. They also used it to remove smoke smell from our cloths, linens and other fabrics. We did remove and replace all of the attic insulation.

If you decide to DIY it, you can find reasonably priced ozone generators on line.



 
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Old 07-28-23, 10:45 AM
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We had a car that always smelled musty, assumed a water leak but never could find one or any indication of water. Rented an ozone generator and put it in there for the weekend, it really helped!

But yea, how do you seal up an attic sufficiently to get the concentration high enough to do anything!
 
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Old 07-29-23, 03:29 AM
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I have to admit I thought I might have manifested having my roof ripped off last nightÖtornado sirens, ridiculous wind and thinking what did I do. 🤣. Thank yíall for the replies. When we did the remodel, on the second floor any exposed old wood I treated with a couple of coats of Kilz before it was closed back up. All new paint and flooring, and in some cases new insulation and drywall. When the hvac system doesnít run, the odor isnít a problem. The ozone is interesting, hadnít thought of that and it certainly could have been done when the attic was air tight. So an attic fan wouldnít do much to exchange the air so that the HVAC system would have fresher air to draw from? Or is that not how the HVAC system works? The roof has a few more years left (we almost could have done a year down and rebuild at this point) and when it gets replaced, is there a chance then to do anything with all the old insulation/sealing to eliminate the old smell?
 
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Old 07-29-23, 06:23 AM
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Jrjka - For the most part the HVAC is somewhat like a loosely defined closed loop system whereby it draws air from within the house via the 'return air' vents and then conditions that air (e.g. heating it or cooling it) and sends it back into the house via the supply registers.

If you are detecting the bad odor coming from the air of your HVAC system - knowing you have already had the ducts cleaned which you said 'was awful' and looked like 'piles of kittens' I seriously doubt the coil in your HVAC was cleaned too. Typically, when ducts are cleaned the coil in the air-handler is not touched.

I strongly suspect the coil in your HVAC is clogged with the same awful stuff that was pulled out of your ducts. When the HVAC is in cooling mode the coil removes humidity from the air - so the coil and its condensate capture structure is damp/wet as its design is to have the condensate water drain-off. However, if I'm right that your coil may be clogged, that damp/ wet condition of the clogged-up coil would only increase the likelihood (and reason) why you continue to still smell that bad odor. Plus, a clogged coil will drastically diminish the efficiency of your HVAC.

Ask yourself - Does a pile of lint, dust, dander and old dead skin cell flakes smell worse if it is in high humidity or damp/wet, or if it is dry?

I highly recommend that you have the coil in your HVAC thoroughly cleaned and disinfected. Doing that may just be all that is needed to totally eliminate that disgusting odor that's driving you bonkers and borderline insane!
 

Last edited by Kooter; 07-29-23 at 06:37 AM. Reason: orthography
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Old 07-29-23, 08:51 AM
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Have you smelled the air coming out of the vents? Is that what smells, or is it just a general smell throughout the house?

If it's from the vents, I'd definitely re-check the vents, check the condenser, and also pour some bleach or vinegar down the condensate lines. In a prior house, I was sure something had died in the vents... but turned out it was just mold/mildew buildup in the condensate drains that was getting sucked back into the airflow. A half-cup of bleach every couple months solved that problem!

If it's just general house smell, I'd work on better air sealing. Sometimes if the HVAC isn't well balanced, it will tend to suck air from the basement/attic pulling in years of dirt smell. Maybe some more air sealing is required too.
 
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Old 08-02-23, 08:28 AM
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Kooter I would have agreed with your assessment except that last summer the 2nd floor system died and we got a new one. So I thought between a new system, some new duct runs and cleaned old runs it wouldnít smell like attic when the air cuts on.

Zorfdt its not the smell of inside the living space, itís the attic smell. So when the ac starts that first warm gust of air out is the worst, but on really hot days the smell lingers in the airflow while the ac is running. So itís like you describe, it must be taking air out of the attic versus just the cold air return on the 2nd level. As for sealing, what are we sealing? The ducts? Is the Ē weĒ a company or a DIY job? As for calling out the Ac company who installed it, if I ask them to balance it, will that make sense? What does something like that run? What I am getting is that no one thinks there is a need for an attic fan.
 
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Old 08-02-23, 10:06 AM
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I'd say you have a very sensitive sense of smell and are probably hypersensitive to a lot of various things. A hot attic in an old house is going to smell like (wait for it), smell like hot, stale air from the attic of an old house. Hot air that is stale has a bit of unpleasant smell to it. But Most people understand and accept that - even with a new HVAC with some new duct runs and a few old duct runs that have been cleaned. That unpleasant smell usually goes away a few minutes after the HVAC starts running. In your case, not so much!

I think you could eradicate all the old attic insulation and install new insulation and it might help enough to please you, but then again, maybe not. Even that might not be enough to get rid of the old house attic smell you are so allergic or hypersensitive to.

I really don't think there's anything you can 'reasonably' do that makes economic sense that will ultimately satisfy your desire for clean, fresh air coming from your 2nd floor HVAC system because of your uncustomary, super exceptional, hypersensitive sense of smell. You might have to result to the only sure thing that provides you with the outcome you so adamantly seek. Either tear off the roof and decking and replace it all, or tear the entire old house down and build back new... Tearing a house completely down is usually only done when the house doesn't meet the needs or standards of the property owner...and that may be the case with your situation...
 

Last edited by Kooter; 08-02-23 at 12:15 PM. Reason: orthography
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Old 08-03-23, 02:03 PM
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I suggest using charcoal detoxing. You can buy multiple of these air cleaning bags and position them around the attic and crawlspace areas. If the problem does not improve, take the bags and put them in the sun for awhile, then return them to the positioning again. These bags can pull horrible smells out! If you have more questions, reach out by searching Attic Health San Diego, maybe I will get a blog up about this soon! Thank you for the idea!
 
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Old 08-03-23, 06:40 PM
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So it’s like you describe, it must be taking air out of the attic versus just the cold air return on the 2nd level. As for sealing, what are we sealing? The ducts?
It can be either.

Attic air may be finding its way into the cold air ducts and just sitting there, waiting to be blown out when the AC kicks on.
Or it's possible that all the gaps are letting that air in. Around light fixtures, holes into walls and out the electrical switches, cracks in the closets, etc. And the AC kicking on is creating a short-term negative pressure, pulling air from wherever it's able to - which is all those cracks.

Either one isn't rocket science. But it means scurrying around in the attic. For ducts, either silver metallic tape (not duct tape) or mastic (sort of a goopy paint/glue) is easily installed - though you need to get around all the ducts.

For general air sealing, take a few switch or outlet cover plates off. Do you see lots of dust and dirt between the wallboard and box? Dirty cover plates on the back side? That's all air movement. Best to seal from the attic, but even caulk around (not in) the electrical boxes can help.
 
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Old 06-19-24, 05:27 AM
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I have the same with a 100 year old house.

Hi:
I know this is a year old, not sure if you are still dealing with this, but wanted to add what I could or see if you have had success with the issue:

I have owned an old house (over 100 years) myself. I noticed the same issues you describe with the upper unit. I have researched a long time and discovered 2 main issues: 1)Through the years I discovered 1 of the issues is that back in the day they allowed people to use the wood bays as HVAC runs with out having to install the ductwork. So years of any creature who got in your house and all their smells would be pulled through as they leave their scents in the wood (among other gross things that current metal ductwork would prevent). Those bays are made of wood and absorb every gross smell. 2) in addition to that I would also smell the "attic" smells. The only thing that ever seemed to help was to use the "dehumidifier" instead of the AC, (I"m guessing because it pulls less air) but the dehumidifier isn't enough when the the heat is too much.

I have tried spraying the return runs (as far as I could reach) with enzymatic sprays, tried sealing them with kill etc. I also had siding done when I first bought the house and I believe they did cover some important areas that were there for attic ventilation. No success with these solutions.

I'm pretty sure the only solution is to a) Completely clean the attic, (maybe a good time to do the ozone treatment others mentioned), then spray the Attic ceilings, walls, bays with some sort of sealant (maybe closed cell insulation) b) spray insulation in all of the bays between the studs, hopefully "encapsulating" the smell and help prevent and new "creatures" getting in and leaving their sent.

After years, this is what I have concluded but would love to know if you found a different solution that worked.

Thanks,
B
 
 

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