My parents have a basement and they painted the walls with dry lock I believe it was called and painted the floor with an epoxy floor coating and after that all the smells and humidity went away. They were able to turn off the dehumidifiers much of the time.

Sent from the Okie state usin Tapatalk

 

Musty odors are highest during active mold growth. Mold accumulates and becomes residual. As you dry the space dew point. the cool surfaces lose surface moisture needed to grow and becomes dormant. The dormant mold has a odor but much less than active mold growth. As time passes the odor will decline. If you want to get rid of it now you must remove the dormant mold by washing with a detergent. If any mold grew between the concrete floor and the floor surface, it should be replaces and the concrete scrubbed and the surface replaced. If the moisture content is maintained low enough to avoid near condensation, the odor will continue to decline.
Fresh air ventilation is important any time the space is occupied. Winter winds and stack effect air will improve the odor problem. Your dehumidifier could have a fresh air inlet connected to the return with dampers to provide adequate fresh air to improve the odor problem. You need about 50-80 cfm until the odor declines to what you want. After that, suggest fresh when the home is occupied.
Also make sure you do not have a damp spot in remote corner where mold may be still active.
Raise the setting to 50--55%RH to reduce the heat build up in the basement. This is low enough to prevent mold growth in most situations and will reduce heat build up.

This is what I do in my WI finished basement with good results. Originally, I removed the old carpet to get rid of the musty odor.
Keep us posted.
Regards Teddy Bear

 

If I had that issue to resolve I would first do an extensive top-to-bottom scrubbing with a industrial soap solution with about 10% chlorine bleach added to it. Then the next day do a second extensive scrubbing with an Odor-Ban type of product. You can use a sponge mop on the walls and ceilings to make it easier. Anywhere there is no ceiling I would spray well with a 10% chlorine bleach solution - use a pump type garden sprayer.

Keeping the RH below 50% has stopped your molds from growing but what you smell is their residual odors. You have to physically clean that remainder out of there. The same way that, after the mice are dead - you have to empty the traps outside somewhere. <g>

If you hate bleach for some reason you can rent (or build: I built both of mine) an industrial strength ozone generator and eliminate the cleaning step one above.

Then paint the exposed concrete walls with one of the moisture proofing products and paint all the finished areas with anti biological paint - usually sold as 'bathroom paint'. For the exposed wood, joists and so forth, spray it all with something cheap like Thompson's water seal. Just use a garden sprayer.

Afterwards I would add bamboo charcoal odor absorbers and keep the RH% below 50%.

PHM
--------

 

Thanks very much for the replies.

As far as the fresh air...thanks for the specs on the needed cfm. What about these ERVs? Are they worth the extra cost? are there particular models to look at? I have had it in my head that getting some fresh air in there is going to help a lot so this suggestion resonates with me...I just need details on what to buy to make this happen.

As far as the cleaning...that makes sense. Have painted some of the (drywall) walls just to change color. Have never seen any evidence of mold anywhere in the basement. But if the smell is there I guess it has to be somewhere. I guess it cannot hurt to wash everything down.

I do fear that if I can't see the mold but can smell it (I'm assuming what I smell is mold) then it is behind the walls/under the floor. As I am the only one it bothers, I honestly will continue to try to minimize it but I'm not tearing out any walls or floors to solve the problem. Oddly the odor seems worst at the top of the stairs. Not sure if that is because mold smell rises? Because it just hits me when opening the door? Or? area seems totally free from any indications of dampness or water damage and I actually had one of these two walls open for other reasons (construction) and saw no evidence of mold anywhere. I'm going to start by washing this area down as suggested.

Seems like no love for the HEPA air purifier? I could never tell for sure if it did anything...but I think the model I got was only rated for 200ft2 or something so I thought maybe it was just too small to make an impact.

It is a vacation home so this time when I left, I left the basement door open. Hoping it helps the smell of the basement more than it hurts the smell of the rest of the house

Again, thanks for the input.

 

Fresh air is nice - and quite necessary overall. But I am also a lifelong fan of electronic air cleaners. The kind which are mounted in the building's air ducts. They seem to be able to clear even smells from the air.

I imagine this is because in humans 'smell' is primarily 'taste' - you actually 'taste' the particles from the air you breathe but perceive it as 'smell' because you are breathing it in. Which, incidentally, always conjures up an interesting thought sequence every time someone farts nearby. <g>

But anyway; EAC's remove something close to 99% of all particles out of the air - so you are no longer 'smelling' them. <g>

PHM
---------

 

I agree with the recommendation to do a detailed clean/wash. Mold not only needs moisture, it also needs food. And dust has sufficient nutrients for many species of mold to grow.

If that doesn’t work, mold could be growing behind drywall, especially if there is a crack in the wall or more general seepage.

If you can stop the mold from growing by starving it of the moisture it needs, you will stop its production of mVOCs, which are the musty odors you smell. However mVOCs can embed into porous building materials and furniture and take time to dissipate; this is where more fresh air will help. Think of it like someone regularly smoking in your basement; he’s now gone but the lingering odors will take time to dissipate.

And the odor being at the top of the basement stairs? That’s where it first hits you and almost never the location of the actual problem.

 

So I know nothing about mold.

With that said, how does it grow behind walls or under floors if it needs food? Are the building materials the food?

There is a built-in entertainment cabinet in the basement. It is made of oak. the inside of the cabinets have a musty smell. we have cleaned that several times (ok my wife has at my request) and while it has helped, it is still there. She used Spray Nine cleaner which I use on the boat with great success. I guess I have to break out the bleach.

I (we) are going to go to town cleaning.

I will add an air exchanger (would really really appreciate guidance on brands/models). I understand it can be tied into the dehumidifier (I believe it even has connections to open/close dampers)...but why would you do this? That is an honest question as I just don't understand the advantage of that as opposed to just having an exhanger on a timer that isn't tied into the dehumidifier.

I will replace the HEPA filter in the air purifier (and could easily be talked into replacing it/supplementing it with a larger one)

I will try to remember to report back in a few months (I hate when threads like this die without a conclusion).

And the odor at the top of the stairs...I think certainly some of it is tied to the impact of opening the door but it seems worse there even coming up the stairs. As I think about it, the stairwell is the only wall area that hasn't been painted. I think I'll clean it real well and then paint it. Come to think of it, ceilings haven't been painted either. Is cleaning painted surfaces and then re-painting a good mitigation plan?

thanks for the valuable input

 

With that said, how does it grow behind walls or under floors if it needs food? Are the building materials the food?

In general, mold needs carbon-based ("organic") materials for growth; something that was biological in nature. The paper-facing found on drywall (which once was a tree) has nutrients for growth, but not the gypsum core. Even dust has enough organic content to support growth. Technically, all this is species dependent (e.g. the species that loves to grow on dust may not have the enzymes to digest the nutrient on drywall paper).

I don't see getting a larger HEPA filter as being beneficial. You want to keep it dry to prevent the mold and keep it well ventilated to get rid of the residual musty odors. Painting a wall/ceiling may provide some improvement on the embedded odors.

 

OK, so I just returned after 4 days with the basement door open. The smell has decreased dramatically...probably to a '2' on a 1-10 scale. Only the pickiest/most olfactory sensitive would likely notice the smell (e.g. me). No noticeable smell has come up the stairs during this time. This gives me hope that an air exchanger will help dramatically as well as this is all the 'door open' has done, at least by my way of thinking.

So I am going to wash this weekend and then get an air exchanger installed. Would still truly appreciate any guidance on the pros/cons of different air exchange systems, especially with regards to the ERVs and whether or not they are worth the cost?

I also bought a larger HEPA purifier. Perhaps it was a waste of money but I bought it so will plug it in. Below is a picture of the HEPA filter from the existing purifier. Obvious 'stuff' caught in the filter. Does the condition of this filter tell anyone anything? This has been running essentially 24/7 for 14 months. Again, thanks for the responses, they are appreciated.

 

Fresh air when unoccupied is of no value and will require the dehumidifier to remove the moisture in the fresh air.
One more time,--Bring in fresh air with the dehumidifier when occupied. You need air for the exhaust equipment like kitchen hood and clothes drier.

pressurizing the home with the fresh air via the dehumidifier will reduce the moisture that comes into the home via wind.

Regards Teddy Bear

 

Fresh air when unoccupied is of no value and will require the dehumidifier to remove the moisture in the fresh air.
...

Thanks for the reply.

I now understand why bringing the fresh air in through the dehumidifier makes sense...thanks for that explanation. My hesitation to setting it up this way is that I believe it will be much more complicated and expensive to install compared to just having the exchanger dump fresh air into the space. But it sounds like that additional complication & expense is worthwhile, and the explanation does make sense to me.

however, I'm having trouble with the snipet above. I had the basement closed-up for 7 weeks as it was not occupied and wow did it get worse. It has taken a long time to get it back to where it was prior to that 7 week shutdown. I'm having trouble understanding how having that stale air, which seems to build up residual musty odor, sit without being 'rinsed' or exchanged with fresh air is a good idea? Even in your previous reply you seemed to imply that the air exchanger should run continuously, even when unoccupied, until the musty odors have subsided to an acceptable level.

I'm probably just misunderstanding you. Thanks for the input, I do appreciate it!

 

Its you home and you live there. Do what you want.

I have got about 25 year of this and learn every day.

One point I must make, basement with drywall on spacers on exterior concrete walls have the possible chance of high humidity between the drywall and the concrete. The Fix for this a closed cell foam on the concrete and a vapor seal on the warm side of the insulation. Foil faced closed cell foam glued to the concrete wall and the foil to the warm side with drywall inside facing the basement space. This eleminates any space for the moist air to grow mold.

Carpeting on concrete has the possibility of moisture between the concrete and carpeting. The fix is to reduce the dew point of the basement air below the temperature of the concrete under the carpet.

Keep us posted on how this all works out.
Regards Teddy Bear

 

I have been leaving the door open when not present at the house and have added a 2nd air purifier. It has never smelled better. I doubt it is the air purifier. I believe it is just the 'fresh' air exchanges that is occurring due to the door being open.

I have ordered a Panasonic FV-04VE1 ERV. This is a small, self-contained ERV that is designed to be run continuously whether or not the room is occupied. I will install it in the ceiling between the joists in the unfinished area. It will bring a constant flow of fresh air from the outside at a selectable rate--either 10, 20, or 40 cfm. It has the added benefit of recovering energy (cooling or heating) from the outgoing air and 'adding' that energy to the incoming air (cools incoming air in the summer and warms incoming air in the winter). It also removes humidity from incoming air in humid weather (transferring it to the dry/conditioned outgoing air) and adds humidity to incoming air in dry weather. I based this selection on research on other sites. I will program the dehumidifier to run in 'vent' mode about 20 minutes of every hour so the fresh air is distributed throughout the basement even when the air doesn't need dehumidification.

Once installed I will experiment with running it continuously at different speeds, with and without the door open, with different vent duty cycles, as well as experimenting with running it only when the room is occupied. I will try to remember to report back here in a couple months with results...I hate when threads like this go without a conclusion.

 

LIke peeing on a forest fire! You need a fresh air change in 4-5 hours minimum. ERVs will reduce a small amount of moisture in fresh air provided the exhaust air is dry. This is nice but will not control indoor moisture.
You need 80-100 cfm of fresh air. You need 50%RH in the space.

What you have is device that has the words you want to here. Keep us posted on this works. It helps others to avoid doing the same thing. Do not feel bad, i have tried the same fix.

During winter, the outdoor air dries out and will dryout the home. This should give you relief until spring.
Again keep us posted.

Regards Teddy Bear

 

40cfm running 24/7 is peeing on a forest fire but 80-100cfm only while the space is occupied (about 4 hours per week on average or ~2% of 24/7) will work? I don't think you're correct (and honestly you have contradicted yourself a few times in this thread). The best part is that we will get to find out! And your math seems off...the space is approximately 8,000 cubic feet. 8,000 cubic feet/40 cfm =200 minutes=3.3 hour 'changeover'...hardly 'peeing on a forest fire' compared to your 4-5 hour recommendation. And in one of your posts you recommended as low as 50cfm. That statement was a small part of deciding the 40cfm would be sufficient. Whoops.

I promise to report back and I for one have absolutely no problem admitting when something I have said or thought or done turns out to be incorrect (or acknowledging when I contradict myself)...so the truth will be written eventually. If it doesn't work as I hope it will, I will say so.

Keep in mind that leaving the door open has made a DRAMATIC impact in a very short period of time (2 weeks) and that is only a passive exchange of air within the house. Furthermore, this impact has been made when basement/main floor temps are about even due to the time of year so any stack effect is minimized. I will admit I do not have a clue how much air is being exchanged with the door open (in cfm's). Perhaps it is a lot more than 40cfm. However, if it is a lot more than 40cfm, then it proves that a lot more than 40cfm only while the space is occupied will not work (contrary to your statements). Why? Because I have often left the door open while down there (and the kids ALWAYS leave the door open--every door for that matter!), and it has had NO discernable impact on the odor. So it is either EQUAL TO OR LESS than 40cfm and makes a big impact when left open most of the time (contrary to your assertions), or it is MORE than 40cfm and does NOTHING when only left open while occupied (also contrary to your assertions). What you're saying just simply does not add up. It may be that I end up needing both more than 40cfm and need it all the time. But I am certain that whatever it is needs to be all the time, at least until the residual odors are flushed out of the room.

Also with regards to your comment about still needing to control moisture when using an ERV...yes, that is correct (actually there will be more moisture to remove in humid weather because you're bringing in more outside air). The dehumidifier will stay put and continue to do that. The point of the ERV as opposed to a normal fresh air intake is not that it replaces the need for a/c, heat & humidification controllers but rather reduces the energy these systems use by helping them, to varying degrees, do their jobs (as compared to an air exchanger without the energy recovering core). As far as having the words I want to here [sic], yes, I do like the words Energy Recovery Ventilator...and that is precisely what it does. To imply otherwise is strange to me. Seems someone feels his toes are being stepped on and for that I feel bad as it was not my intention.

While I absolutely do not agree with your main assertions that 40cfm running continuously will do nothing and that 50-100cfm running only when the room is occupied is sufficient (wow do those statements strike me as 'out there'), I nevertheless appreciate the participation in the conversation and believe the conversation in this thread has forced me to think and learn and make the decisions I did...so that is good. We'll see how well it works.

 

Controlllng musty odors are more dependent on low %RH than ventilation. Maintain %RH low enough to prevent mold growth is the key. This also includes damp spots that may be more about water leakage than %RH. And you right, 40 cfm of ERV plus natural air change will improve conditions even through short of the fresh air change in 3- hours suggested by some.
I did not know you would be so sensitive about salty comment, sorry.
Most important to understand that low humidity controls biological growth like mold and dust mites. Air change purges indoor pollutants and renew oxygen.

Keep us posted on how it all works out.
Regards Teddy Bear

 

OK, updating here in case anyone ever does a search for how to remove residual mold and/or mildew odors especially from a basement.

I bought & installed the Panasonic FV-04VE1 ERV. Success!!!

I am very very impressed with this unit. Seems like a lot of bang for your buck. I got it for less than $400. It is very easy to install. One single 5.25" hole through the house for both in & out air supplies. They have a clever in/out plenum to make this possible. The unit itself is super compact & easy to install. It is extremely quiet. I have been running it at the max (40cfm) for a couple weeks. Of course it took a few days to start impacting any odors, reinforcing the point that the idea that this would work when only being run while the room is occupied is completely ridiculous. After a week the odor significantly decreased and after 2 weeks it is essentially gone. I will now start experimenting with running the unit at a lower speed (options of 10 & 20 cfm).

A few points about the unit if you are trying to figure out whether to go with an ERV or a normal fresh air intake duct tied into a dehumidifier or other hvac equipment or possibly you might even consider using a normal exhaust (e.g. bathroom) fan.

Obviously, the biggest difference is the crossflow enthalpy exchange core. This is what transfers heat out of the incoming air in the summer and transfers heat into the incoming air in the winter. It also adds moisture to dry incoming air and removes moisture from humid incoming air. Looking at the efficiency ratings of the core, it certainly works, but nowhere close to 100% efficiency. It is more efficient at adding heat to the incoming air in the winter than removing heat in the summer. And the cost of the unit is not excessive...only a couple hundred more than a top quality exhaust fan.

The other big difference (and really what pushed me) is the balanced air in/out. With a simple exhaust fan, or a simple intake duct tied into a dehumidifier for examples, the tightness of your house can and will impact, sometimes significantly, the flow of fresh air. As an example, if you have an intake fan that's rated at 50cfm, but you install it in a very tight house with no way for the air to leave your house, you are not going to get anywhere near 50cfm. You need air flowing out if air is flowing in. You, of course, could add an air outlet with a damper that actuates w/the air intake damper, but the system starts to get complicated to design and install. The ERV has all this technology built into a single unit (dampers, etc) so that if run at, say, 20cfm, you are going to get 20cfm no matter how tight the house is. My house has been energy audited, reinsulated and sealed, and retested and is very very tight. Something that makes a fresh air exchange system all the more important.

One drawback is that these units are not designed to run in extreme cold. They will bypass the enthalpy core at very low temps and function as a normal exhaust fan when it gets very cold. Cape Cod has a much milder winter climate than inland MA so this will not be a big deal for my application (will only shut down on the very coldest days) but if you live in a place that has long, very cold winters you will have to think about this more.

Overall I would highly highly recommend this unit as a way to deal with residual air quality issues, especially in a basement. You obviously have to cure the root of the problem first (in this case keeping the humidity consistently low), but after that, a unit like this is an inexpensive, easy to install, energy efficient way to get fresh air into places that normally don't get enough. As houses become better insulated & tighter, the number of these units that will be installed will increase dramatically. Hopefully my learning experience helps another homeowner with similar circumstances.

 

Please update us after a full year once you have experienced it through an entire humid season. I am really curious how it will do.

Sent from the Okie state usin Tapatalk

 

Lets not get too excited without a couple years of typical year around weather before we celebrate. Normal homes with moisture generating occupants and occasional damp weather systems need time demonstrate how they work.

Get a couple good %RH meters in the far corners of your home and let the time pass.
Give us the feed back on how it all works.
Wish you the best.

Regards Teddy Bear

 

Right, the smell is gone, which was my goal. It was done by installing a compact, quiet, energy efficient, inexpensive device. But let's not 'get excited'. Instead lets wait a few years in hopes that some internet know it all can somehow still claim victory after posting self-contradicting utter nonsense that lacked even common sense. One thing is for sure...I will not be taking anymore 'advice' from 'teddy'. LOL :grin2:

 

The main message is keep the space dry to control biological growth. 40 cfm plus natural ventilation is better than most.
Glad that the problem is solved. Ok maybe I got a little handed on my comments about fire control. I will accept the slap down and I am sorry.

Keep us posted next summer.

Thanks for the lively discussion.
Regards Teddy Bear

 

Now you need to have a Home energy audit done with a air quality test. Id be curious to know what your co2 levels are along with VOCs. I did that and it was a real eye opener.

 

As an update to this thread:

The ERV continues to work amazing magic in my basement. It is honestly the freshest, best smelling air in the house.

I have found a negative though--energy use has gone up. This must be due to the dehumidifier needing to run more frequently as new outside air is introduced constantly. I started with the unit a the max setting, 40cfm. Worked extremely well, so I decided to see if 20cfm would be sufficient. It was, at least in the month of November here on the Cape. So, once I saw my energy bill jump up for October (compared to October 2019), I decided to see if the lowest setting, 10cfm, would be sufficient. I have had it running at 10cfm for about a month now and there is no noticeable degradation in smell. It still smells 100% mold/mildew free and, honestly, the freshest air in the house. The air is relatively dry around here in the winter, so I'm not sure 10cfm will be enough when spring comes, but we will see and I will keep this thread updated for people who do searches in the future.

I cannot stress enough what an amazing impact the ERV made on the air quality in my basement. Highly, highly recommend it.

 

How much of an electrical cost did you have?

 

I find it amusing that a homeowner claims to have learned more from “The Internet” about IAQ and dehumidification in a few weeks or months than Teddy Bear. :gah:

 

Just go back and read how many times he contradicts himself. Now that amuses me :bsing: Complete and utter nonsense.

You don't need to have a lot of time in an industry to recognize when someone is making stuff up as he goes along :det:. And, while I understand where you're coming from, one of the most important abilities any of us can have is to know when to say "I don't know" or "I'm not sure". Clearly he did not know what he was talking about, that much is objective fact at this point.

It's important for all to remember that common sense is king, and, ultimately, the proof is in the pudding. The emperor has no clothes.

 

Really cool thread I'm learning a lot. I've run into situations like this fairly often.

"If you hate bleach for some reason you can rent (or build: I built both of mine) an industrial strength ozone generator and eliminate the cleaning step one above."

Mikey do you think a basic ducted air-scrubber with ozone would do the trick for something like this? Or is that not enough. You figure if he needs ozone for his basement he might as well duct it in for his whole house while hes at it.

 

Mikey do you think a basic ducted air-scrubber with ozone would do the trick for something like this? Or is that not enough. You figure if he needs ozone for his basement he might as well duct it in for his whole house while hes at it.

I would recommend NOT using ozone in a home. Ozone is a respiratory irritant and it reacts with other chemicals in a home to create secondary products that are also harmful.

Even if it is only used one time in an unoccupied home at high concentrations, ozone can cause harm to the home by breaking down rubber and soft plastic. In the presence of humidity, it can form hydrogen peroxide and cause bleaching.

Besides, killing mold with a shot of ozone doesn't address the underlying problems that caused it to grow in the first place! Mold will only grow back.

 

From what I’ve read, ozone is bad for humans and houses.

 

Chlorine probably isn't the best thing for them either. <g>

PHM
--------

 

I've been reading up on them. I figured for this application it might be practical. I'm still trying to figure out how he set up his fresh air. Having a hard time visualizing it through text. Did he just duct the return side of the dehumidifier into the return duct then put in a fresh air intake somewhere off the return? Cape post some pictures next time your out there.

 

And they lived happily ever after!

Homes have more natural infiltration during cold and windy weather. A fresh air chagne in 3-5 hours is common during coldest months of the year. During the mild, calm months of the year when windows are closed, could be a fresh air change in +12 hours. Outside oxygen is 21%. Less than 15% oxygen decreases oxygen in the blood. We do not know all of the long term effects of the various gases in our house air.

I like your "know it all" spunk. May even match mine.

Very interesting.

Keep us posted.

Regards Teddy Bear

 

Chlorine probably isn't the best thing for them either. <g>

In keeping with other common household appliances, such as: hairdryers, electric mixers, and fans - any high efficiency EAC will produce trace levels of ozone when they are running. However in the extensive testing of electronic air cleaners performance, both in test chambers and in actual homes, under normal operating conditions, ozone levels measured are in the range of .005 to .020 parts per million - which are well below the indoor safety levels set by the FDA.

Outdoor air is often pretty high in ozone content - sometimes exceeding 0.120 PPM. In general, levels below 0.080 are considered acceptable for outdoors, but the FDA sets a level of 0.050 with a 24 hour a day exposure as the maximum indoor ozone concentration acceptable. And, as I said before; an EAC can be expected to add about 0.005 PPM.

So why not have the cleanest air possible in your home? <g>

PHM
--------

 

I hope im allowed to post here. It isnt marked as AOP. IM curious also how this does.

Everyone keeps repeating to control the humidity below the mold growth point and also get that dew point lower along with finding and eradicating the existing growth.

It seems to me that an air purifier is just masking the problem at this point? Like for example the air was previously at a 6 in smell and you have lowered it to 2. At 6 an air purifier could not keep up but at a 2 it can. Have you not just lowered the problem to the capacity the air purifier can handle and not actually fixed the issue? But at the same time, vapor barriers and such may be a cost prohibitive solution post construction, so maybe this is indeed the best ROI for the problem?

 

The air pretty much everywhere is full of molds. If you leave food out it gets moldy, right? The mold didn't just spontaneously generate - it was in the air, landed on the food, found the conditions right for it to grow - so it grew there on the food.

Outside of a NASA grade lab there is never going to be a mold-free environment. All you can do is to discourage the mold, that is already everywhere, from growing. It has been established that mold growth requires a >50% RH.

One benefit that I can think of to the EAC's that I prefer is that they remove molds from the air stream and interference type air filters do not.

What do you mean by: "keep up" and: "not keep up"? Keep up with what?

PHM
-------

 

My reading failed me. I thought the OP installed a filtration system to correct the issue. I see now that I was mistaken.