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  1. #1
    Join Date
    Aug 2007
    Posts
    175

    Best way to dehumidfy a basement?

    First, thanks to everyone who assisted me with my A/C dilemma. Now, my next one. I have an unfinished basement in my home. It is appx. 450/sq ft. I am storing a bunch of stuff down there. It has four small windows. I plan of "eventually" finishing it. What would be the best way to dehumidfy this basement now and in the future. Thanks in advance...

    PS: I am using a dehumidifier, but it heats the place up....

  2. #2
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
    Posts
    1,582
    You can just run a couple of small box fans set on the floor blowing in different direction and crack one of the windows to allow fresh air into the basement. Or you can build a chute running from the floor at the bottom of one of the window up to the window and place a box fan in front sucking the air into the chute and out of the basement with a window open on the other side again to allow fresh air in. As long as there is air moving about the area it will stay realitively dry but once the room or area is closed off with no air movement you begin to get that musty smell.

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,374
    Quote Originally Posted by sandman512 View Post
    First, thanks to everyone who assisted me with my A/C dilemma. Now, my next one. I have an unfinished basement in my home. It is appx. 450/sq ft. I am storing a bunch of stuff down there. It has four small windows. I plan of "eventually" finishing it. What would be the best way to dehumidfy this basement now and in the future. Thanks in advance...

    PS: I am using a dehumidifier, but it heats the place up....
    The problem with basements is the wall/floor temperature is below the dew point of outside air. In addition, consider that sucking large quantities of outside humid air in, makes your entire home wet. You need only enough outside air to purge polutants and renew oxygen. The outside ventilation air must be dehumidified. So forget outside air unless you are in arrid climate.
    When you use a dehumidifier, stop dehumidifying at 50&#37;RH. Running the dehu beyond 50%rh overheats the space and waste energy. Get a %RH meter and monitor the %RH. A good 50 pint dehu should keep your space dry and not overheat. If you want to maintain <50%RH throughout your home, check out a small whole house dehu like, Sante Fe Compact or Ultra-Aire 65H. Regards TB
    Last edited by teddy bear; 06-20-2008 at 06:36 AM. Reason: missing words
    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"

  4. #4
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    better still, keep the moisture out of the bsmt!
    -- drains
    -- gutters & downspouts extended 10ft out
    -- sloped earth 10ft out
    -- waterproofing on outside bsmt walls --

    better construction is to have egg size rock layer over geofabric next to earth-- drained, pvc under concrete floor
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  5. #5
    Join Date
    Feb 2008
    Location
    Dallas & Longview, TX
    Posts
    629
    Quote Originally Posted by cem-bsee View Post
    ....better construction is to have egg size rock layer over geofabric next to earth-- drained, pvc under concrete floor
    Can you elaborate? Is this under basement floor or walls? Can't picture it.

  6. #6
    Join Date
    Mar 2008
    Posts
    118

    This is what I did

    I have a similar problem. Although, my basement is 1000sf. I put a small dehumidifier and plumbed it to a condensate pump to take the condensate outdoors automatically though a sillcock.
    I set the RH at 50% and run the unit on lowest speed. I don't experience too much heating. It's not a glorious solution, but it works for me.

    I've often thought about putting a product like Drylock on the walls, although that is as far as it's gotten. I used a product called Thoroseal in my last home and it helped quite a bit with moisture issues in the basement. Best wishes to you.
    Greg

  7. #7
    Join Date
    Dec 2006
    Location
    Northern VA
    Posts
    389
    Quote Originally Posted by cem-bsee View Post
    better still, keep the moisture out of the bsmt!
    -- drains
    -- gutters & downspouts extended 10ft out
    -- sloped earth 10ft out
    -- waterproofing on outside bsmt walls --

    better construction is to have egg size rock layer over geofabric next to earth-- drained, pvc under concrete floor
    Couldn't agree more..

  8. #8
    Join Date
    Dec 2002
    Location
    Southern MN
    Posts
    259
    Gotta keep the water away from the house for sure.
    A drainage system around the house would help to drain the water away from the house.

  9. #9
    Join Date
    Mar 2008
    Posts
    87
    Just wondering what everyone keeps the Realtive Humidity of their basement at? With my Whirlpool on Turbo Fan and the setting on Dry, it hovers around 58% - 60% RH near a far corner quite a ways from the dehumidifier. I have calibrated the meter using the salt test and it came out to 76% RH so it should be 1% off. If I put it to the Very Dry setting (The highest not including Continuous Run) It seems to run all the time even when the humidity outside is low and has trouble getting below 52%. The area is about 1200 SF and I am using a Whirlpool 75Pint. Just curious if the humidity is to high. Thanks

  10. #10
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,977
    My deep rock walled 1937 home's basement is way too humid in the spring & summer months.

    I insulated the cold water pipes, as they were often times dripping water all over the floor.

    I use a floor fan & open small windows & a side door when it is not too hot.
    I also open the clean-out on a very large & high chimney, that up-drafts.

    I looked at units at Lowe's & didn't see any rated above 50 pints.
    They were Frigidaire brand, didn't buy one.

    I know that would lighten the latent load on my first floor half-ton room A/C.

    In your experience, what brands & models do you consider to be the most efficient & best dehumidifiers?

  11. #11
    Same problems here. My house was built around 1900, and has those thick (granite?) stone walls. Rain infiltration is not really the issue, I have a full gutter system, good grading, etc., but the walls are nearly always "damp" in the spring, summer, and fall.

    If I do nothing, humidity is off the charts and it quickly begins smelling musty, affecting the first floor as well. I've been running two LG 65 pint dehumidifiers at all times, and it brings the humidity down to roughly 75%. (As shown by the humidifiers, which could be substantially off I suppose.) That's low enough to eliminate the musty smell, and is the best I've been able to come up with for now....

    The basement is about 1900 sf, 8-9 ft ceilings. In addition to the exterior walls, there is a additional 4 brick thick wall that runs the center line of the basement, which also seems to wick in water from below. It also breaks up the space making it difficult to keep air fully circulating.

    Waterproofing the exterior of the foundation is 100% out of the question, due to a city location and proximity of other houses/adjacent property lines.

  12. #12
    Join Date
    May 2008
    Location
    Spfld, IL
    Posts
    108
    Quote Originally Posted by udarrell View Post
    I looked at units at Lowe's & didn't see any rated above 50 pints.
    They were Frigidaire brand, didn't buy one.

    Lowes sells a 70 pint Frigidaire. I just bought one there this weekend.

  13. #13
    Join Date
    Mar 2008
    Location
    Jackson, NJ
    Posts
    176
    Quote Originally Posted by udarrell View Post
    My deep rock walled 1937 home's basement is way too humid in the spring & summer months.

    I insulated the cold water pipes, as they were often times dripping water all over the floor.

    I use a floor fan & open small windows & a side door when it is not too hot.
    I also open the clean-out on a very large & high chimney, that up-drafts.

    I looked at units at Lowe's & didn't see any rated above 50 pints.
    They were Frigidaire brand, didn't buy one.

    I know that would lighten the latent load on my first floor half-ton room A/C.

    In your experience, what brands & models do you consider to be the most efficient & best dehumidifiers?
    I bought one of the 50 pint Lowes units (Frigidaire)a couple of weeks ago. I can't attest to how long it will last, but I'm pretty happy with it. Seems very sturdy, the bucket is nicely designed w/ a nice carrying handle built into it (nice touch). Its quieter then the 7 year old Whirlpool that I tossed when I moved. Took 1100 sq. ft basement from 90% to 60% in one day and has had no problems keeping it there. *I keep it set to 60 - not sure if thats optimal but thats what I have it set at*

    My house was sitting unoccupied after construction for a good 4 months or so. I have poured concrete walls and insulation in the ceiling, so I'm sure its going to take some time for everything to wick into the air and end up in the bucket of this unit. Its noticeably more comfortable down there now though.

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