Page 1 of 2 12 LastLast
Results 1 to 13 of 15
  1. #1
    Join Date
    Jan 2009
    Posts
    10

    How to eliminate musty basement smell

    My home has a finished basement that has a musty basement smell that I would like to eliminate or reduce. I have done quite a bit (see below) already but I am posting here because I am now considering using ventilation to treat the problem. Sorry in advance for the long post...

    Background:
    - Drywall hung on metal studs, carpet glued to cement with no pad, heat ducts from forced air furnace, but no return ducts
    - History of water intrusion where the carpet has gotten wet about a foot away from the wall during heavy rains (please read my entire post before responding with alarming information about mold)

    What has been done
    - Drywall and insulation removed along 2 of the three drywalled outside walls (the only two walls where there was water intrusion). No evidence of mold on concrete or drywall.
    - Whole house mold testing performed using the "dust method" by a reputable company and examined by their on-staff microbiologist. Also had a site inspection performed by two reputable mold remediation companies. Also had multiple blood tests performed on myself to look for immunoglobin responses that would indicate exposure to mold. All tests have come back negative.
    - Removed all carpet that has gotten wet. Glue still remains on concrete floor and the carpet that has remained dry has not been removed
    - French drain system being installed outside and repairs to leaking glass block windows being repaired inside to fix water intrusion issues.

    Next Steps
    By removing drywall and performing various tests I am fairly confident that I do not have a mold issue, but I am still left with an odor issue.

    I have spoken with a number of contractors and have received a couple of recommendations to install an HRV (we live in Michigan) in the basement to provide fresh air ventilation. One recommendation was to install the HRV detached from the forced air furnace to cycle the air in the basement as often as possible (stale air return and fresh air input would be placed on opposite sides of the basement).

    Has anyone had success with using an HRV to treat odor issues?

    Let me know if you need more details...I could go on forever.

  2. #2
    Join Date
    Mar 2002
    Location
    Concord, CA
    Posts
    2,635
    Iím surprised you havenít received any responses. Consider this a bump rather than a useful reply.

    The big three damage functions (as taught by a self-assured air quality expert who seems to walk his talk) are moisture, heat and UV. In your scenario itís pretty obviously moisture. Treating the odor means getting rid of the moisture. Youíre on that path now. Less moisture should mean less or no odor after a while. Iím sure thereís no new information for you there.

    As for an HRV, get enough dilution and youíll inevitably dilute the odor away. Source control is obviously a much better solution than an HRV.

  3. #3
    Join Date
    Jan 2009
    Posts
    10
    I agree with the strategy of source control, but it is not always an option. I have tried to go after all of the controllable potential sources like carpet and drywall/insulation.

    I also noticed that my sump pump was smelly. Houses in my area have a pit in the basement where water from the drain tiles that surround the house drains. There is a pump inside of this pit that pumps the water out to a sewer in my backyard. To help with the sump pump odor I have installed a radon system which seals the sump pit with a cover and has a vent pipe and fan tapped into the drain tile. It's a bit of overkill, but it was the best way that I could think of to seal the smelly sump and try to de-pressurize the soil gasses that might be contributing to my musty basement smell.

    So, I have tried to go with the source control method first, but I'm not sure if it will be enough. That is why I have started looking into a dilution method such as an HRV.

    Another part of my question with this issue is how to install the HRV. I have a forced air furnace that has a Skuttle on it to bring in fresh air. However, I would like to bring even more fresh air into the basement area. Can I have a Skuttle on the furnace and an HRV working independently at the same time or am I going to create some other issue doing this? Basically, I would keep the Skuttle on the furnace intake and then have new intake/exhaust runs created for the HRV. The HRV would then pull air from the basement and bring in fresh air into the basement independent of the furnace.

    Any thoughts would be appreciated...even ideas on what could be causing the basement to smell musty.

    Thanks.

  4. #4
    Join Date
    Mar 2002
    Location
    Concord, CA
    Posts
    2,635
    I think you understand this, but just to be sure: When I say source control, Iím talking about water Ė not carpets or drywall. Moisture is likely your main issue, not the substrates where mold grows. Iím thinking you might need to give the newly installed drainage more time to dry things out.

    The HRVís Iíve seen use the furnace blower to move the air. Someone probably makes an HRV with its own fan. If not then youíd need to have someone rig a blower or air handler to the HRV. HRVís are obviously not 100% efficient. The basement is going to get colder than the rest of the home. Itís all doable of course. Itís just a question of money. I have a feeling that once you find out how much itíll be youíll decide to wait and see if things dry out more on their own.

    If moisture isnít the issue then perhaps you have gas seeping in from some underground source. Concrete is porous. Perhaps it needs a sealant.

    Whatever you do, do so at your own risk. Iím just throwing stuff out there - partly because the two or three real IAQ experts on this board and 77.5 pretenders (of which I am one) havenít piped up yet.

  5. #5
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,371
    Sorry that I missed your original post as I was on vacation.
    Consider that when basement humidity rises to +70%RH, mold grows on all cool surfaces. Mold has grown on all cool surfaces after +48 hours of high moisture exposure. The amount of mold that depends on the actual moisture levels and time. After you dry the space, it takes time for the dormant mold to lose it's odor. Ventilation is good but can create a new set of problems for you that could include more mold growth. Green grass climates have many months of the year that have high enough outdoor dew points to make cool basements damp enough to grow mold.
    The most important issue is keeping the indoor space free of wet spots and <50%RH throughout the space. Next is enough fresh air to purge indoor pollutants and renew oxygen. An air change every 4-5 hours is considered enough fresh air purging and oxygen renewal. During your winter weather, you may be getting enough dry fresh air. If you home is excessively dry without humidification, you are getting enough cold weather ventilation. As the weather warms, natural ventilation decreases quickly. Comparing -0F to 40^F outside temps decreases natural ventilation 50%. The down side of spring/summer/fall fresh air ventilation is the excess humidity that makes your basement damp. 24 hours of 100 cfm of fresh air has 25-70 lbs. of excess moisture/day that must be removed to maintain <50%RH in the basement. Limiting fresh air ventilation to the hours of occupancy decreases the moisture load. During hot weather, the a/c will remove much of the excess moisture. The ideal solution to this problem is a ventilating dehumidifier. These units blend the desired amount of fresh air with house air when the home is occupied. The dehumidifier controls excess humidity and circulates the dry, clean air throughout the home. These units are capable of providing fresh air and maintaining <50%RH without any a/c operation. There are several makes on the market. Some are more efficient and durable than others. I work for thermastor. Thermastor is the pioneer of the concept Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  6. #6
    Join Date
    Jan 2009
    Posts
    10
    TB, thanks for the detailed response. I had not heard of a ventilating humidifier, but did a little reading on the concept and it seems that it could be of use in my situation. I'm a little confused about the following things though:

    1. During the winter months my basement and the rest of my house are typically about 25-35% RH. Obviously I do not need dehumidification during this time. Does the ventilation part of the dehumidifier run during the winter to provide fresh air?
    2. I currently have a Skuttle connected to provide fresh air to my furnace. Would it make sense to remove the Skuttle and re-use its outdoor air intake (6") for the dehumidifier?
    3. If I remove the Skuttle will I still be able to achieve a positive pressure in my home with the dehumidifier ventilation? I believe that some of my odor problems may be due to soil gasses, so I would like to pressurize my house while de-pressurizing the soil (with a radon system).

  7. #7
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,371
    Quote Originally Posted by doylebry View Post
    TB, thanks for the detailed response. I had not heard of a ventilating humidifier, but did a little reading on the concept and it seems that it could be of use in my situation. I'm a little confused about the following things though:

    1. During the winter months my basement and the rest of my house are typically about 25-35% RH. Obviously I do not need dehumidification during this time. Does the ventilation part of the dehumidifier run during the winter to provide fresh air?
    2. I currently have a Skuttle connected to provide fresh air to my furnace. Would it make sense to remove the Skuttle and re-use its outdoor air intake (6") for the dehumidifier?
    3. If I remove the Skuttle will I still be able to achieve a positive pressure in my home with the dehumidifier ventilation? I believe that some of my odor problems may be due to soil gasses, so I would like to pressurize my house while de-pressurizing the soil (with a radon system).
    Ventilating Dehumidifier??
    1. I do not think any more fresh air or dehumidification is required during coldest winter months. The ventilation part provides as much fresh air as you want and when you want it.
    2. You would connect the 6" fresh air to the ventilating dehumidifier without the skuttle.
    3. Positive pressure during cold weather is next impossible because of the large amount of fresh required. The negative pressure under the slab is the best method of stopping soil gas from entering the home. During the spring-fall seasons, 75 cfm of fresh will change the pressure differential throughout the home. Check thermastor.com
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  8. #8
    Join Date
    Jan 2009
    Posts
    10
    Yes, ventilating dehumidifier...sorry, typo. Anyway a few follow-up questions.

    You say that I should have enough fresh air in the winter, but my concern is that I still have a musty basment odor during this time. I could use the ventialting dehumidifier to pull in fresh air and dilute the odor, but I do not get any heat recovery when it is cold out. That is why I was looking at an HRV.

    Would a traditional dehumidifier like the Sante Fe products be a better way to go? I would equip it with a charcoal filter to help with the odors year round and then use the dehumidification during the spring/summer/fall months. Are these charcoal filters actually effective?

    Or perhaps I just need to be more patient and allow the odors to dissipate. As I mentioned, I had a few instances of water intrusion, and I have done some things to dry out the basement inside and out (drainage, removing carpet, etc.).

    Thanks.

  9. #9
    Join Date
    Jan 2009
    Posts
    10
    It's probably rude of me to bump my own thread after only a couple of days...

    Anyway, I'm looking for anyone who has experience using a dehumidifier with an activated charcoal/carbon filter. I am sure that the dehumidifier will help with odors just by bringing down the moisture content in the area, but I am wondering if the carbon filter actually does anything. I am a little skeptical because I have no experience with these.

    Thanks.

  10. #10
    Join Date
    May 2005
    Location
    Lubbock Texas
    Posts
    773
    A charcoal filter will loose a lot of it effectiveness in high humidity situations. They absorb all of the moisture and lose there ability to absorb VOCs

  11. #11
    Join Date
    Jan 2007
    Location
    Minneapolis, MN
    Posts
    415
    Don't treat the symptoms with a product. If you still have an odor issue then you need to find the source of the moisture and correct it. also remove ALL moisture damaged material... not just dry them out. And yes the odor is from a mold/mildew problem. Is the basement in a negative pressure as compared to the outside? This can draw in moisture and soil gasses.

  12. #12
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,371
    You can use charcoal on ventilating dehumidifier. Charcoal is not that good at controlling light odors. Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  13. #13
    Join Date
    Jan 2009
    Location
    Fairfield county Connecticuit
    Posts
    778
    get a dehumidifier like the aprilair central dehumidifier model 1700 or 1720

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event