# How to - prevent basement mold



## crazymountain

10 Ways to Prevent Basement Mold

Basement mold is a common problem in homes that have damp, dark basements. Mold is a fungus, which grows fast in moist, humid conditions. Once it establishes its presence in your basement, this problem is very difficult to get rid of. Mold causes several health problems such as asthma, infections, cough, rashes, congestion and allergies. The best way to prevent mold growth is to control humidity and moisture in your basement. If for any reason the humidity and moisture in your basement is hard to control look into purchasing a humidifier. 

1. Monitor Humidity Levels 
High humidity levels provide the perfect growing environment for mold. You must ensure that humidity levels within your home, especially the basement, are within acceptable levels. Use a hygrometer to measure the humidity level. A humidity percentage of 45 or more is high, and can be conducive to growth of mold.

2. Use a Dehumidifier
If you detect high moisture levels in the basement, invest in a good quality dehumidifier. This appliance is quite effective in keeping humidity levels under check. 
Dehumidifiers come in different sizes and price range. Research what is best for your particular situation.

3. Avoid Growing Plants Indoors
Plants grown in the basement provide a good diet for mold and mildew. Only grow plants in sunny, airy locations in your home. Avoid the basement for cultivation of any sorts.

4. Reduce Congestion in the Basement
Try to keep your basement free of clutter. Too many objects and storage items block the free flow of air, and reduce ventilation. Items such as clothes and books stored in the basement provide food on which mold and mildew thrive. If you do not have an option, store minimal quantities of such items, away from direct contact with the floor or walls. Plastic tubs is a great storage idea for your basement.

5. Avoid Storing Wood in the Basement
Wood is another ideal habitat for mold to grow in. Never store wood in the basement. An open, airy location is the best choice for storing wood.

6. Ensure that Water is Directed Away From Your Home
The boundary around your home must be sloped in such a way that snow and rain are directed away from the house. If not, water and moisture will pool around the structure, and increase moisture and leakage problems. In such a situation, mold is almost inevitable. If it is hard to redirect the water away from your home, you may need to look into putting French drains in.

7. Take Care of Spills and Leaks Immediately
If there are any leaks in the basement, sometimes because of heavy rain, take care of it immediately. Wipe the water from the area and dry it thoroughly. Use of a dehumidifier and heater will accelerate the drying process. Also investigate the requirement of further insulation for your walls.

8. Insulate Water Pipes in the Basement
Generally, cold water pipes in the basement show condensation of water on the exterior. Insulating such pipes reduces the humidity levels in the basement.

9. Use an Exhaust Fan
Air out stale, humid air and allow the intake of fresh air with the use of an exhaust fan. Try to open doors and windows to the basement regularly.

10. Reduce Humidifying Factors
Avoid drying wet clothes in the basement. Make sure appliances such as dryers, stoves, heaters and air conditioners exhaust to the outside, or else the humidity can rise significantly. Avoid carpets and wood flooring in the basement.


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## AfterDinner

You might also try sealing concrete block if your basement is built with such. If you have a studded basment that is unfinished, you could insulate and add a vapor barrier(ie plastic sheeting).


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## Maintenance 6

crazymountain said:


> 10 Ways to Prevent Basement Mold
> 
> Basement mold is a common problem in homes that have damp, dark basements. Mold is a fungus, which grows fast in moist, humid conditions. Once it establishes its presence in your basement, this problem is very difficult to get rid of. Mold causes several health problems such as asthma, infections, cough, rashes, congestion and allergies. Mold does NOT cause these problems. It may exacerbate the severity for those that alrready suffer from those issues, but has NOT been proven to be the cause.The best way to prevent mold growth is to control humidity and moisture in your basement. If for any reason the humidity and moisture in your basement is hard to control look into purchasing a humidifier.
> 
> 1. Monitor Humidity Levels
> High humidity levels provide the perfect growing environment for mold. You must ensure that humidity levels within your home, especially the basement, are within acceptable levels. Use a hygrometer to measure the humidity level. A humidity percentage of 45 or more is high, and can be conducive to growth of mold. Common household molds that form on building surfaces generally require 60% or greater RH or .6 water content.
> 
> 2. Use a Dehumidifier
> If you detect high moisture levels in the basement, invest in a good quality dehumidifier. This appliance is quite effective in keeping humidity levels under check.
> Dehumidifiers come in different sizes and price range. Research what is best for your particular situation. A dehumidifier should be a last resort. Locate any specific moisture sources and correct them as required. Then retest moisture levels
> 
> 3. Avoid Growing Plants Indoors
> Plants grown in the basement provide a good diet for mold and mildew. Mildew is a specific type of mold that thrives on the leaves of living plants, but nowhere else. Common leaf molds are classes of mildew. Only grow plants in sunny, airy locations in your home. Avoid the basement for cultivation of any sorts.
> 
> 4. Reduce Congestion in the Basement
> Try to keep your basement free of clutter. Too many objects and storage items block the free flow of air, and reduce ventilation. Items such as clothes and books stored in the basement provide food on which mold and mildew thrive. Any organic material is mold food. If you do not have an option, store minimal quantities of such items, away from direct contact with the floor or walls. Plastic tubs is a great storage idea for your basement. Plastic tubs can become mold incubators by trapping moisture. Especially when placed on cold floors where latent moisture can condense in the materials inside the tub.
> 
> 5. Avoid Storing Wood in the Basement
> Wood is another ideal habitat for mold to grow in. Never store wood in the basement. An open, airy location is the best choice for storing wood.
> 
> 6. Ensure that Water is Directed Away From Your Home
> The boundary around your home must be sloped in such a way that snow and rain are directed away from the house. If not, water and moisture will pool around the structure, and increase moisture and leakage problems. In such a situation, mold is almost inevitable. If it is hard to redirect the water away from your home, you may need to look into putting French drains in.
> 
> 7. Take Care of Spills and Leaks Immediately
> If there are any leaks in the basement, sometimes because of heavy rain, take care of it immediately. Wipe the water from the area and dry it thoroughly. Use of a dehumidifier and heater will accelerate the drying process. Also investigate the requirement of further insulation for your walls.
> 
> 8. Insulate Water Pipes in the Basement
> Generally, cold water pipes in the basement show condensation of water on the exterior. Insulating such pipes reduces the humidity levels in the basement.
> 
> 9. Use an Exhaust Fan
> Air out stale, humid air and allow the intake of fresh air with the use of an exhaust fan. Try to open doors and windows to the basement regularly. Cross flow ventilation will reduce moisture under the right conditions. Be certain that you are not introducing cold air into the space that may accelerate condensation.
> 
> 10. Reduce Humidifying Factors
> Avoid drying wet clothes in the basement. Make sure appliances such as dryers, stoves, heaters and air conditioners exhaust to the outside, or else the humidity can rise significantly. Avoid carpets and wood flooring in the basement.


11. Keep the area clean. Common household dust is gourmet mold food.


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## DIY_Diva

This gets harder in old houses (mine was built in the late 1800s) that have had a lot of tenants, and not a lot of upkeep. 

Also, Maintenance 6, you say that cold air exacerbates mold conditions? Why is that? I've been told to keep a fan constantly running to prevent mold from growing in a relatively damp area.


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## Maintenance 6

Agree. It is more of a challenge in older buildings. What I said was that cross flow ventilation will reduce moisture in the right conditions. What you don't want to do is to deliberately inject cold air into a damp space and drive temperatures down below dew point. You then risk creating condensation which increases the risk for mold. 
Molds that grow on common houshold materials need three things to thrive. An organic food source: paper, wood, leather, cotton, household dust, etc. In a normal house, it is very difficult to control the food source, although keeping things clean will help. Second it needs temperatures in the 40-100 degree range (not to be confused with certain food molds that will live in lower temperatures). It is practically impossible to control molds by temperature. Third, they need moisture in the 60-99% relative humity range or .6 water content. This is really the only condition that you can readily control.


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## concretemasonry

In a basement, avoid fiber glass because it can be a breeding ground for mold since it holds (not absorbs) moisture (condensation, leaks, etc.) and collects dust and dirt from the air and from construction that just feed the mold.

Dick


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## Maintenance 6

Kilz is a sealer, not a fungicide. It is good for sealing areas after they have been cleaned and disinfected but is not a treatment by itself.


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## DesignEye

Good information. We live in the damp woods of the pacific northwest so these tips will come in handy. Keeping mold away can be nearly a fulltime job in this neck of the woods.


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## design_lover13

I purchased a dehumidifier that is larger than needed for my home because I've read that they're far more efficient than smaller ones with regards to electricity usage. However, this is a unit whose fan runs all the time to monitor the humidity level. Not only is it loud, its also soaking up electricity by running all the time.

Does anyone use timers on their dehumidifiers? I feel like its a waste to run it 24/7. Whats a proper humidity level? I find that my basement bathroom's toilet tank sweats unless I set my dehumidifier to around %35 humidity. I could insulate the tank itself but I've read that isn't really a long term solution?


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## Maintenance 6

30-60 percent is an average range for living space. Some people install a mixing valve on the supply line going to toilets to add a small amount of hot water. This tempers the supply water to room temperature to eliminate the sweating. Even without it, the sweating will stop when the tank reaches a temperature above dew point.


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## oldhomeowner

I was told by a friend that building codes in Canada include ventilation requirements that all but eliminate mold. I have been trying to find this without success. I have a home built in 1889 that was built on a "stone wall" foundation. I hired a guy who scraped all of the walls, hand packed cement into all of the holes, sprayed a sealer over the walls and then applied some kind of "cement" spray that has now done a fantastic job of almost totally eliminating any water. We have since painted every wall / floor with "floor" paint, and so far it seems to be working. (I still have a hole in the floor where a sump pump used to go, but I am planning on sealing that with cement.) I put clear plastic covers over most of the window wells on one side, but now I realize that that will make ventilation problematic. I am still going to try and set up fans, as a more economical way of reducing moisture than the dehumidifier which could cost a ton. I am also intrigued by the ionizers and other devices to kill spores. Thoughts? Comments? Suggestions?


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## Maintenance 6

I really cannot help you with Canadian ventilation requirements. I highly doubt that they are so good as to "eliminate" any concern for mold, although proper ventilation will go a very long way in contolling moisture which in turn is essential to preventing mold. Devices which claim to kill mold spores have not been shown to be particularly effective in the real world. The most likely place for mold to form is in corners and crevices, where air is stagnant and likely to have higher humidity levels. Devices that modify the air, such as ionizers and ozone generators do not effectively reach places where air flow is minimal, such as these same corners and crevices. Proper ventilation will tend to flush the treated air anyway. Keeping humidity and moisture levels under control is your best bet.


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## AGWhitehouse

AfterDinner said:


> You might also try sealing concrete block if your basement is built with such. If you have a studded basment that is unfinished, you could insulate and add a vapor barrier(ie plastic sheeting).


Not a great idea to cover a wall cavity with plastic in a basement space. moisture enter from the exterior in to the wall cavity and has nowhere to go. It collects inside the wall and harbors the growth of mold. Basements need to breath...

Vapor barriers (or significant retarders a.k.a Class I or II) should never be used in a basement space unless they are directly applied to the exterior concrete/masonry walls surface. I don't even like that, but if you're insistent on it, that's the best place for it.


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## Canucker

oldhomeowner said:


> I was told by a friend that building codes in Canada include ventilation requirements that all but eliminate mold. I have been trying to find this without success. I have a home built in 1889 that was built on a "stone wall" foundation. I hired a guy who scraped all of the walls, hand packed cement into all of the holes, sprayed a sealer over the walls and then applied some kind of "cement" spray that has now done a fantastic job of almost totally eliminating any water. We have since painted every wall / floor with "floor" paint, and so far it seems to be working. (I still have a hole in the floor where a sump pump used to go, but I am planning on sealing that with cement.) I put clear plastic covers over most of the window wells on one side, but now I realize that that will make ventilation problematic. I am still going to try and set up fans, as a more economical way of reducing moisture than the dehumidifier which could cost a ton. I am also intrigued by the ionizers and other devices to kill spores. Thoughts? Comments? Suggestions?


I live in Canada and I can tell you that I've seen housing developments put up in the last 10 yrs that still use a fiberglass blanket with a vapour barrier built in to it that insulates the top 4 ft of basement walls. I guess it really depends on the builder as to whether they are up to date on the latest techniques or not. A lot of them won't change until the building code does, so the minimum gets done to pass inspection.


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## AtlBizHub

Hello, 

Does it make a difference if a cool or warm mist humidifier is used in the basement?

Thanks,


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## alain33

"2. Use a Dehumidifier
If you detect high moisture levels in the basement, invest in a good quality dehumidifier. This appliance is quite effective in keeping humidity levels under check. 
Dehumidifiers come in different sizes and price range. Research what is best for your particular situation."

I just use Dehumidifier, it works find for me. Thanks for your other ways. good!


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## Maintenance 6

AtlBizHub said:


> Hello,
> 
> Does it make a difference if a cool or warm mist humidifier is used in the basement?
> 
> Thanks,


It certainly could. It depends on what the realative humidity levels are in the basement. Adding more humidity to a basement that already has a fairly high RH could easily drive it into the danger zone for mold. Whether it is cool or warm mist really only affects the absorption time for the vapor. Water vapor that is warmed will absorb into the air faster than cool. How long it takes for that vapor to condense out of the air onto a cool surface that is below dew point won't change. Dew point is determined by the relative humidity and air temperature. Once relative humidity reaches 100% for a given air temperature (saturation point), the moisture will condense out of the air. It will rain in your basement. By then, you will have gone past the minimum level that mold needs to thrive.


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## jsmith48

thanks for the info, a lot of my neighbors have older houses in the town i live in. they always struggle with the mold down there.


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## federer

AGWhitehouse said:


> Not a great idea to cover a wall cavity with plastic in a basement space. moisture enter from the exterior in to the wall cavity and has nowhere to go. It collects inside the wall and harbors the growth of mold. Basements need to breath...
> 
> Vapor barriers (or significant retarders a.k.a Class I or II) should never be used in a basement space unless they are directly applied to the exterior concrete/masonry walls surface. I don't even like that, but if you're insistent on it, that's the best place for it.


what do you suggest for basement insulation?


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## DocWard

AGWhitehouse said:


> Not a great idea to cover a wall cavity with plastic in a basement space. moisture enter from the exterior in to the wall cavity and has nowhere to go. It collects inside the wall and harbors the growth of mold. Basements need to breath...
> 
> Vapor barriers (or significant retarders a.k.a Class I or II) should never be used in a basement space unless they are directly applied to the exterior concrete/masonry walls surface. I don't even like that, but if you're insistent on it, that's the best place for it.


My house sits on a sloped lot, with the north wall of the basement being completely below grade, below my garage floor, and my south wall being nearly entirely above grade, with full size windows. Since an external barrier and membrane aren't really an option, what suggestions are there for preventing moisture and mold from the inside?

I have some issues with mold, and moisture is a definite problem. I have the fiberglass "diaper" going around the upper half of all but the south wall, where it covers the entire wall.


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## AGWhitehouse

federer said:


> what do you suggest for basement insulation?


http://www.buildingscience.com/docu...=resources/high-r-value-foundation-assemblies


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## AGWhitehouse

DocWard said:


> My house sits on a sloped lot, with the north wall of the basement being completely below grade, below my garage floor, and my south wall being nearly entirely above grade, with full size windows. Since an external barrier and membrane aren't really an option, what suggestions are there for preventing moisture and mold from the inside?
> 
> I have some issues with mold, and moisture is a definite problem. I have the fiberglass "diaper" going around the upper half of all but the south wall, where it covers the entire wall.


People have used drain boards along the interior foundation face and tied it into a perimeter drain tile beneath the floor. This gives a channel for any incoming moisture to escape into the drainage system.


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## DocWard

AGWhitehouse said:


> People have used drain boards along the interior foundation face and tied it into a perimeter drain tile beneath the floor. This gives a channel for any incoming moisture to escape into the drainage system.


Our basement has a channel around the perimeter, between the edge of the slab and the wall. I have heard this referred to as a "floating" slab, but I am not sure that is the actual term. I would have to check, since it has been awhile since I looked, but I believe there is a drain there in one corner.

That being the case, what are my options? Do I then go ahead and put up a vapor barrier, or what should I do?


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## AGWhitehouse

You would need to take up the perimeter of your slab and install a system that looks like this: http://www.terrafirmalandscape.net/p7lsm_img_4/fullsize/int_2_lg_fs.jpg

The pipe is encased in filter fabric and drains either to daylight or a sump pit. The black piece is the drainage board. Notice the egg-crate like dimples that create a channel for water flow. This board should extend up the face of the wall. Then you can place rigid insulation board over the drainage board and then frame out a wall from there.

I will say that this is not the ideal solution. Excessive water migration through your foundation walls will not help its integrity over it's life span. Excessive water should really be treated at the exterior, site unwilling or not....


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## DocWard

AGWhitehouse said:


> You would need to take up the perimeter of your slab and install a system that looks like this: http://www.terrafirmalandscape.net/p7lsm_img_4/fullsize/int_2_lg_fs.jpg
> 
> The pipe is encased in filter fabric and drains either to daylight or a sump pit. The black piece is the drainage board. Notice the egg-crate like dimples that create a channel for water flow. This board should extend up the face of the wall. Then you can place rigid insulation board over the drainage board and then frame out a wall from there.
> 
> I will say that this is not the ideal solution. Excessive water migration through your foundation walls will not help its integrity over it's life span. Excessive water should really be treated at the exterior, site unwilling or not....


I appreciate the answer, but I guess it still leaves me scratching my head about what to do with the walls short of digging away under my garage, which means getting rid of a big chunk of my driveway and moving my central air, along with the necessary bracing to keep it from falling in and making it safe to work under, then putting up a barrier on the outside of the wall. Sounds like it would cost nearly as much as the house cost to build.


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## AGWhitehouse

DocWard said:


> I appreciate the answer, but I guess it still leaves me scratching my head about what to do with the walls short of digging away under my garage, which means getting rid of a big chunk of my driveway and moving my central air, along with the necessary bracing to keep it from falling in and making it safe to work under, then putting up a barrier on the outside of the wall. Sounds like it would cost nearly as much as the house cost to build.


Curtain drains that are away from the structure can serve to re-direct the mass water flows around the structure. That would alleviate a great deal of hydraulic pressure from the foundation and would not require excavation directly against the structure.


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## DocWard

I should mention that I am not planning on finishing my basement beyond a minimal amount. My plan is to leave it "rustic" but usable for things such as a workout area and hobby area. I would like to put in a mold resistant drop ceiling, and perhaps some sort of inexpensive flooring, such as matting that can be taken up / replaced if necessary. The most important things for me are lack of mold / mildew, moisture, and better lighting.


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## Atticus

Thanks for this guide. Genuinely guilty for doing some of these things... genuinely stupid of me not realizing too.


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## DocWard

Well, I do have some good news. As I was cleaning my basement, I found two paperback books in the trench between my basement wall and floor. They had become soaked and swollen, and I think they were acting as dams, allowing the basement to flood. Since I have removed them, we have had substantial rains, and while the walls themselves get wet, there is no dampness on the floor.

As for the walls, I think that I need to re-grade come spring, because I am seeing moisture in areas very close to where my walls are above grade. I looked, and the slope that was once away from the house is no longer that way. Hopefully dryer walls will mean less mold. I am working hard to keep things clean as well, and either moving, sealing, or eliminating those things that mold dines on.


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## metal

Mold loves moisture. Keep everything as dry as you can by running fans and making sure you have no leaks. Mold can be a lot more dangerous than people give it credit.


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## Mills314

AfterDinner said:


> You might also try sealing concrete block if your basement is built with such. If you have a studded basment that is unfinished, you could insulate and add a vapor barrier(ie plastic sheeting).


In regards to this, my basement was Dry Locked before framing, however only 1 coat was done because I was told that it was sufficient. There is no vapor barrier on the outside of the framing either, however there was no evidence of water in the basement prior to the finish, and the outside of the home has a great drainage system.

Think I should worry?


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## Maintenance 6

No. I wouldn't. If there is no evidence of moisture anywhere, why worry about it?


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## robut

*Basement moisture and fans 9/1/13*

September 1st 2013

My home was built around 1895, The owners in 1913 jacked the home up and put block walls and flooring.
The basement consist of 5 rooms divided by block walls, with door ways to each room.
I have always had some moisture in the air in hot July and August months 
I would set a fan on a timer to circulate the air I did the same this year also.
Yesterday ,, I went down to grab a few old wood chairs and a card table what the heck they were really moldy.
The card table has a vinyl covering this too was moldy.

I have not had this problem before? someone mentioned that a fan would cause the air to be too cool and cause molding conditions.
Perhaps the air condition running caused the heat pipes to drip with condensation un noticed by me. I don't frequent the basement that often.

I'll buy a new dehumidifier if I can find one with a good review for about $250.00 Most have bad reviews some good Hummm 
They cost about $55.00 a month to run Can they be used on a timer 12 0n and 12 off ? 

I will check back in a week Thanks
Deck Hand


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## Maintenance 6

A fan will circulate air, not change the temperature of the air. If the air contains excessive humidity, then circulating it will do no good. Circulating air across a cool surface may promote condensation and result in mold growth. If you can't circulate fresh air into the space, the a dehumidifier is the best bet. What you want is to run it until the humidistat on the machine shuts it off. It may run 3-4 hours and shut off or it might run 20 hours. It's impossible to say. $55.00 per month seems pretty high for a dehumidifier.


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## mosy15

Hello Everyone,
Hi all, I really think this was a good post, and the responses of all it has done even more interesting 
Good day!


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## begal

You need to wash your concrete basement walls and floor on a regular basis if it is not dampproof. Better to get bluesealed from outside. 
Other problem in a basement is no air floor around the floor, so you need fans down there or sort of exhaust.

/watch?v=jR2IbdGXUSU


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## SeniorSitizen

Put an unsalted cracker in the basement. If it stays below 12 percent moisture your basement is in good condition moisture wise.


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