Humidity problem

[Audioactive]

hi there, i removed the wardrobe away from the wall and i find this surprise..



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This wall is going to be covered with bass traps, once i cover it i won't be able to see the situation behind the traps.

I was wondering if there is a way to treat humidity...i've been suggested to cover the wall with plasterboards with aluminium foil toward the wall, but i'm not sure this will make any difference,

what is your experience?
thanks

[Steve says]

In my basement I covered the walls with a special wallpaper. Aditionally I have got a display wich shows the humidity and in which range it is fine. Airing the room also lowers Humidity!

[Audioactive]

hi steve, thanks for answering,

could u be more specific regarding the special wallpaper and the display you're using??thanks

[Steve says]

The display is a humidity display that you can get in every hardware store. The wallpaper is a special wallpaper that is covered with aluminium and styrofoam. Opon this you attach the normal wallpaper. It keeps the walls from beeing cold and so Humidity doesn´t wet the wall because of cooling down the "water vapor"
A tipp with attaching the aborbers would be to leave some space between the wall and the absorber so this gap can air out and the air is not "standing" at the same place all the time.

[Hannes_F]

Definetely keep an air gap behind your traps, and that gap must not be closed to the sides.

I have been reading into the problems of condensate water lately and have to say this topic seems to be vastly underrated by most DIY people. It is a serious problem field within building physics already, and all the more if dealing with insulation products at outside walls.

[Hannes_F]

BTW the cure to dry this up is not to keep your windows open tilted all day (because of the fresh air). This is a typical problem in bedrooms or living rooms ... people leave the window open for long, especially in the night, and then close it in the morning and let the warm air captured in the rest of the house heat the room up. THIS IS WRONG.

The problem here is that the walls get really cold and the warmer air in the other rooms contains humidity which then condensates at the coldest spots in that room (usually an outside wall, behind furniture or near windows).

The cure is to heat the room after you close the windows and keep the door to the rest of the house shut. That way you heat up the cold air from outside which makes it dry. You need to get that wall warm and keep the door closed. Then open the windows entirely for some minutes every hour for complete air exchange ... and heat up that new air again.

[Audioactive]

the room is in the basement, we use it as storage room, where we keep all the staff we don't use, old books, old forniture and so on...the wall is the one far away from door & window.

i guess, by moving downstairs and using machines like computer etc, the heat of the computer plus the heat of the people who will be standing there during the day could reduce the problem.

I'm not clear about how to setup the traps, If i leave a gap to the sides of the wall, the absorptive properties of the bass traps won't be as effective (?) . I really want to avoid that, since the room is quite small and i'm definetely gonna have some heavy reflections!!

Do you think i could avoid gaps on the sides somehow?? Maybe Building a Modular system of traps, that i can remove from time to time to let the air out?!??

Could it be a good solution??
THanks

[ritelec]

Is this mold from condensation? Or is it mold from a wet foundation.

Aside from french drains or removing earth from outside to get at the issue,

Check downspouts outside and see if there's any source thats bringing water to that point of the basement. Redirect that water away from the house if there is.

Clean the existing mold with ammonia (use a fan an get plenty of air during process).

Research and get a good basement waterproofing type of paint and apply (I actually had this problem in my moms basement some 35yrs ago as a kid setting up to play in a band, the paints still there, alittle bubbly in areas, but its held up).

Maybe add some plastic over the top. (wood,plastic,masonry anchors)

Keep small gap between trap and wall.

Keep fingers crossed.

Good Luck

PS... Thats if it's just alittle damp and mildew. If it's wet and your getting water thats something else.

Again, Good luck with it.

[Rod Gervais]

This is (of course) dependent on where you live - and i know nothing of where the OP lives - so cannot advise him directly.

However, people being in the room in the room do not help the situation......

Although the people introduce heat to the space - they breathe out just as much vapor as they breathe in - plus they perspire when they exert energy - and thus introduce even more humidity into the air. People are a part of the problem - not a part of the solution.

This is how it works folks.........

Mold is caused by one of 2 things..... either directly entry of water into structure - fix the leak solve the problem, or due to high humidity levels caused by other than direct entry.

Now - keeping windows open is not a solution to the problem (nor is it a cause of the problem) - if is was - entire houses would be full of mold on the outside of the building in the sumer months when it is (typically) colder inside of the building than it is outside..........

And this is not (generally) the case - however - the shaded sides of a building outside can very well get moldy - this is a problem with my home - and we have no trees or anything else on that side of the house to lock the air and humidity in - just the fact that is is in a shaded area - which means cooler than the rest of the building - in even moderate weather - with our moisture levels - is enough to give mold the conditions they need to form and thrive.

So fresh outside air does not solve the problem.

Nor does it cause the problem........... in the summer time you will typically have as many or more problems inside of a home than you do in the wintertime...... yet the house all around is typically cooler than the surrounding air (with the exception of the roof) and yet it does not become covered with mold.

So we can discount the fresh air (in general) as being either the cause or the solution.

Homes generally have air conditioners working in the summer months to cool the air.......

So you begin with hot moist air outside of the building - which migrates into the building that is being cooled......... no matter how you try to lock out the moisture there will be migration, there's leakage around windows - you open doors - there are ventilation points that connect directly to the outside world (bathroom vents for example - that only work to exhaust when they actually run - and are otherwise a path (in either direction) for moisture.

OK - so you have a migration of warm moist air into the home - and what happens when you cool air? You increase the relative humidity.......

It's really that simple.....

This issue with colder weather outside and the problems related to condensation on the inside of the building face is more the above in reverse.

Physics still dictates that the warmer air migrates to the colder surface - nothing changes in that regard - except now the inside surface of the building is warmer than the outside air, in which case the moisture that is locked inside of the house will condense if it reaches "dew point".

This migration is dictated by the 2nd Law of Thermodynamics which states (in part)

"Heat flows spontaneously from a hot body to a cold one"

(There are 2 other parts to the 2nd law - but this is the one that concerns us and causes the issue.)

However - another condition that also occurs in the cold weather is that we generally heat our homes - which means that the relative level of moisture in the air is decreased - this due to the same number of grains of vapor being encase in an expanded field of air.

An easy way to witness this increase/decrease of relative humidity would be to simply blow up a balloon and seal the end.

The balloon will have a certain number of grains of moisture inside of it - this being whatever was carried with your breath as you exhaled to inflate the balloon.

Now - take the balloon and place it inside of your freezer and go check it in a few hours.

What you will find tis that the balloon is quite deflated compared to the condition it was in when you placed it there......... yet it still has exactly the same number of grains of vapor as it did before...... this means a smaller volume of air (due to cooling) with exactly the same number of grains of moisture......

An increase in relative humidity.

The exact same thing takes place inside of your home.

Now - in the case of a basement below (or even partly below) grade you have another condition that is introduced into the mix....... and this is (again) dependent on where you live - although it will happen at some depth anywhere in the world where the is dry land)

That is that the earth (once you are below the depth of frost, which is around 42" here where I live) tends to maintain relatively constant temperatures year round. Here they are around 52 at 30' depths - and around 46 to 50 degrees (F of course) at 4' depths.

This is (of course) highly dependent on water table - soil types - but in general it pretty much holds true - your basements are generally cooler than an unconditioned house in the summer - and warmer than you might expect (without being heated) in the winter.

This creates perfect conditions for the moisture in the air to condense on the face of the basement wall.

This is typically much more prevalent in the winter than in the summer months strictly due to the higher temperature levels in the home in the winter - which again create conditions that will follow the 2nd law...... the heat (and humidity) in the home migrating to the cooler basement - where the RH is increased - and the warmer moist air wants to condense on the cooler surface.

None of this is unusual - not of it is all that deep - and none of it creates an insurmountable obstacle.

In the OP's case the first order of business should be to remove all of the affected areas and replace them with good clean uncontaminated drywall.

You might well find that there are (even much larger) deposits of mold inside of the wall cavity. In which case it is important for you to remove that as well.

Be certain to wear a respirator is you intend to do this yourself. The EPA has a good set of guidelines to aid you in doing this safely and effectively. Below is a link to that site:

Mold Cleanup Guidelines | Mold | US EPA

Now - the reason you want to do this is because mold does not die if you remove it's food source - it simply becomes dormant - and will come back to active life if the moisture ever returns - even for short periods of time.

Once it is gone I would be very cautious about installing anything that is designed to provide a mold free surface.........

I have been through this on numerous properties for clients of mine - some of them very large hotel properties - and the problem with special wallpapers or paints is that they can very well mask the problem - keep it hidden behind them while mold forms to the point where it can become a very serious health risk........

Remember that these treatments do not take the rest of your structure and suddenly make it mold resistant - they just create a mold free surface....... mold could still be developing behind those surfaces.

The ONLY way to create a mold free environment is to take away that which is needed for the mold to produce in the first place.

And that is moisture......

What this boils down to is properly dehumidifying the space (I am assuming in this case that there is not something outside of the building allowing the infiltration of water - bad caulk joints, improperly flashed assemblies - leaky roof, etc., etc., etc.)

Humidity levels really should not exceed 45% RH (the EPA says 60% - however my personal experiences have indicated that 45% is a much better target. 30% tends to lead to dry raspy throats.)

Now - in the summer that can be accomplished with properly treating the space with air conditioning - which will dehumidify the air as the air is cooled provided that the system is properly designed to allow long enough run times.

In the winter months you may well have to use either a mechanical dehumidifier (use of a cooling coil to produce the temps needed to create dew point) or through the use of recycled air and desiccants.

I hope this helps,

Rod

[Audioactive]

hi everyone, i've been reeding your suggestions plus some other sources...

i'm wondering if the white stains are saltpetre..in that case, i have 2 problems to treat...even tho they are caused by the same problem..moisture..

i've got reasons to believe that humidity is coming up from the ground throu the walls, so, the problem is "wet fundations", i've checked in other parts of the basement and its fine, the only place with problem is tha wall that used to be behind a "wall" of old wardrobes, so air couldnt easily pass,

So now i should do this steps.

1- clean the mold with ammonia and let it dry (if the wall is bad, best to dig into the wall to clean everything up properly).
2- Paint the wall with waterproofing Paint
3- live a gap between wall and Traps in order to have more air ventilation
4- Avoid the condition that created the mold on the first place by using dehumidificators and keeping the humidity at not more than 45-50%.

did i miss anything?

thanks everybody for help.

[jsipich]

I'm banking on foundation issues.

1) Turn down the humidity level in the house (most have a knob to adjust).
2) Keep a dehumidifier downstairs - I do and have no issues - then again it's just my "man cave" and my studio is upstairs. I maintain 35% year round humidity.

[ritelec]

Originally Posted by Rod Gervais

"Heat flows spontaneously from a hot body to a cold one"
Rod

Always wondered why I was attracted to my wife.



Thanks for the detailed explanation Rod .

Rich

[Oneya]

For the sake of humidity in my studio in lower level/basement (it was bad, like 85% saying on my thermometer) i had whole foundation of the house waterproofed.
they digged all around the house, tared and it was layers of stuff they applied.

Even as i cant get grass to grow at certain areas no more at all (lol) where digging accured, humidity levels are are on about 30% average and going to %LO readings on my meter.
it was expensive, but extremely important as i was starting to get mold behind the moldings.
had that area completely threated and cleaned, and didnt had no issues ever sience.