How do you avoid Basement Moisture

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saxmchn

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Hey,
I'm about to build a studio in my basement. I know it needs to be as dry as possible. Should I build a sub-floor? waterproof the walls? run a de-humidifier? Are there certain things that you do when building in a basement??
thanks
 
I would like to know the answer too - I have a moisture problem in my basement and was wondering how I could remove it. For now I have to have the windows always open - which is not really secure and off course can damage equipment... So I must always remove my mics and everything... and it sucks!!!

Beathoven
http://www.nowhereradio.com/beathoven/singles
 
I have a fairly large finished basement that gets a little out of hand sometimes. It's hard....I run two dehumidifiers (one in one half of the basement and one in the opposite half) most of the time and turn em off when I'm working. Thats about the only thing I can imagine working.



heylow
 
I finished a room in my basement not too long ago.

You definately need a subfloor with a vapor barrier. I used treated 2"x4"'s laid on face with blow-in insulation between and a dual vapor barrier of 4 mil polyethylene and then 5/8" OSB sub-flooring.

You should stud out your walls and use a vapor barrier backed insulation as well as the polyethylene vapor barrier to seal up the room against moisture. Remember that the vapor barrier goes on the room side of the walls.

If your room will be heated and cooled by the main house HVAC system, moisture should be no problem. The relative humidity in my room stays at around 42% in summer and 35-38% in winter.
Airconditioned air is usually de-humidified and heated air is usually dry to begin with so you should not need a de-humidifier if your construction techniques are sound.

The vapor barrier is often overlooked but it is extremely important in assuring your room stays dry.
 
The best way, but a huge amount of work , is to start from the outside. Dig a trench down to the footings. Coat the exterior with a tar based waterproofing compound. Lay corrugated drain pipe (with holes) in a bed of gravel around the entire structure exiting at the lowest point.
I had a house built about 5 years ago with a full basement using these techniques , and so far, absolutly no moisture.
 
Flatrock has nailed it!!!

Unfortunately, when you have a masonary wall below ground level, the only correct waterproofing MUST be on the outside to create an impenetrable barrier against any moisture.

Sealing the inside surface on established buildings is only a temporary success (unless the outside surface has been treated), as sooner or later the moisture in the masonary will build up behind the inner surface treatment causing it to deteriorate.

Good airflow is possibly the best thing regardless of what moisture sealing is in place.

:cool:
 
OK, my house is about 7 years old, when they built it, they coated the foundation and provided good (not extensive but good) drainage around the house. I currently get a minimal.. by that I mean about a 4 sqft area on one wall that "sweats" in the summer. I have been planning on putting the vapor barrier between the concrete walls and my room-in-a-room walls.

Sennheiser - you suggested that the vapor barrier go on the inside of the wall... but that will mess with Johns inside out wall design I am going to use.

Is the vapor barrier outside the walls going to be a problem? what kind of trouble (odd smells?) am I in for?

Ausrock - I have been thnking of a way to ventilate around the outside of my rooms... any ideas?

Cheers
Kevin.
 
Kevin,

While basements as such are not the "norm" here, homes which are built on sloping ground frequently have a two storey design, even if the bottom level is only a garage. In my case the whole floor area is two storey with the house built on a steep block of land, our studio room (18.5'x22.5') is at one end of the downstairs area. Consequently, at the back of the studio, the floor level is about 8' below ground level whilst the front studio wall leads out onto our front porch. A past owner of the house has at one time built a timber framed inner wall approx 1' in from the rear and side brick wall, creating virtually a room within a room around half the studio.......................hope I haven't been too long winded, but I appear to have a similar problem with that air space between the walls.

So far, the only solution I have come up with is to mount an exhaust fan in the outer brick wall (where it is above ground level) which will allow sufficient exchange of air. I may actually use this fan to remove "stale" air from the studio as well...........it will just mean I have to provide a junction box for the ducting.

If your room is totally below ground level you will have to have ducting for both the removal and replacement of the air and I would imagine that placement of the intake and outlet in relation to each other will be of some importance to achieve maximum efficiency.

:cool:
 
walls and floors

Would it be wise to use 2x4's for the sub floor AND put up
2ndary walls with plastic film for moisture barrier? At this point, I don't see any indication that the walls OR floor have a moisture problem and digging out around the foundation isn't really an option. I've considered a humidity gauge to monitor the content as well.....time will tell......I REALLY enjoyed seeing everyones studio in the studio forum. I'll post pictures in a few months when I get it together....
 
sax,

If you have a bare concrete floor, lay a sheet of plastic over it or sit some cardboard boxes there and you may be surprised at how much moisture may leach through the concrete. It may take a while to appear but it nearly always does.

Similarly, sitting any timber framing on the concrete will have the same problem. The first answer is to put your timber floor frame on neoprene pads and allow for air movement beneath the floor. In regard to building "inner" walls, the same thing applies.........allow space for air flow and if necessary find some way of forcing the air around this cavity. It would be advisable to paint some form of anti-fungicide timber sealer on the underside of the flooring and backside of the wall sheeting before you assemble things.

:cool:
 
VERY good idea...
Is there a concrete floor sealer out there that would
keep most of the moisture out? would it be something like...
for the floor:
Seal the floor,
lay plastic cover down
apply sealer to 2x4's
lay sub-floor
cover with plywood
lay carpet

for the walls,
apply sealer to the walls,
paint, apply sealer to 2x4's
...then what material would be most suitable for the walls???
 
I would aviod sealing the existing floor or walls as all you will do is stop the concrete/masonary from "breathing" which will trap any moisture and possibly over time cause structural deterioration.

Try something like this;.........

Existing concrete floor
3/8" neoprene support blocks
timber floor frame (preferably sealed)
plastic (if you desire)
floor sheeting (sealed on the underside)
carpet or other covering.

If the wall frames are to be attached to the existing wall then you should use nylon or neoprene to space the timber studs off the wall and use fixings (ie; dynabolts) that are moisture resistant. Seal all timber thoroughly, use a wall sheet that is moisture resistant and seal the back of that sheeting as well.

If the inner walls are to be free standing from the existing wall I would still be sealing all framing and using moisture resistant sheeting.

It will still be important to allow air movement around the structure to minimise moisure build up.






:cool:
 
The vapor barrier ideas presented here are spot on. Here in what is really the high desert, we don't have much problem with moisture- but we used those techniques anyway when finishing out the basement studio area.

Average humidity in the summer runs about 22-25%, and in the winter runs 7-10% (!) so moisture isn't generally a big issue- but expansive soils certainly are, because whenever it _does_ finally rain, the floor moves up and down a bit. Sailing the seas of cheese, so to speak.

In the wintertime, we use a whole house humidifier that evaporates about 12 gallons a day of water into the central air system, and we can barely drag the humidity _up_ to 20%. We cook a lot of pasta in the winter, seems like- my wife's a vocalist, and trying to sing in single-digit humidity ain't that pleasant! You can't win... Using central ventilation to move the humidity around can be a huge win, if you can do it...
 
Flat rock is right.

If you have water coming into your basement, and you build a subfloor, you are only hiding the water/moisture under the subfloor, which is a near-perfect environment for mold.

If you coat the inside of the foundation/floor with a sealant, you are still allowing the water into the CONCRETE and eventually it will weaken, dissolve, leak, crack, and break apart. Not in a week mind you, but long term this is not the correct answer.

The only way to really solve a drainage problem is to dig down, seal the outside of the foundation (Personally, I would use something thick like tar, but thats me), install drainpipes with holes and slant them downwards about 3-4 degrees to a "T" and attach to the sewer, or exit into the street depending on your landscape.

Anything else just buys time and is a waste of money. I learned this the hard way, after a ton of damage was done by moisture/water, and ripping out everything in the basement, redoing it, AND fixing the problem on the 2nd tray, was more work than doing it right the first time.

Plus, you can dig for free, it just takes a while :)
 
Frederic,

You are close to the mark when you suggest using tar...........there are bitumous paints available for just that purpose, but I think what sax is looking for is suggestions on minimising moisture problems, as excavations may not be an option.

I know if I was building from scratch what I would be doing, but as is often the case, it is sometimes necessary to work with what you have.

:cool:
 
maaaaaany years ago I owned a different house than the one I just bought. The water table was such that I often received a 2-3" swimming pool (free of charge) in my basement during severe thunderstorms.

This is how I discovered my mold alergy :(

Anyway, after redoing all the stuff on the inside, keeping the moisture out, about 3-4 years later the house started to "settle". Huh? A 200 y/o house just now settling?

Anyway, the foundation in the back corner of the house apparently decided to crumble due to erosion. Some of this water entered the house anyway, but I kept applying the DIY inside water sealer. Anyway, the end result was really big guys with jacks, supporting the corner of my house with this wooden brace thing (and jacks), breaking out the foundation, and redoing that entire corner.

Once that was done, a large trench against the house was dug out, the outside of the now exposed foundation was repaired and sealed (and other parts needed major repair too but I hadn't had a problem - YET), and the trench was filled with gravel, drainpipe, and the problem was completely solved.

Then I spent 6 more months bleaching the mold out of the basement. I eventually was relocated for work, but the new owners smelled the mold (and the bleach) instantly, and tried to use it as a negotiating point.

Tar or paint or seal the inside, thats perfectly cool. The reason why I'm so passionate about this particular issue is I learned the hard way digging IS the only option if water entry is a problem, and I learned this the hard way, with a very high financial penalty. I'm sharing my experience in hopes that other might not suffer the same way I did.

I dunno about you, I'd rather spend 11K on studio gear instead of cinder blocks and big guys with jacks :)



ausrock said:
Frederic,

You are close to the mark when you suggest using tar...........there are bitumous paints available for just that purpose, but I think what sax is looking for is suggestions on minimising moisture problems, as excavations may not be an option.

I know if I was building from scratch what I would be doing, but as is often the case, it is sometimes necessary to work with what you have.

:cool:
Click to expand...
 
Some "easy" fixes

These are pretty obvious, but if you haven't checked this it could help. Check the grading of the ground outside of your house. You should be able to see the ground sloping away from all of the outer walls of your house. If it is level or slopes towards the house, water will accumulate and work its way into the basement. This is the #1 cause of water in basements. Easy solution is to get some top soil and build up next to the house until the natural slope takes water away.

For a wall sealer, I use UGL Drylock. It is basically a paint that is very thick like a paste. It is absolutely the best product I have used for this.

I'm going through this same process on my house right now. The key is to find the sources of any water that you can and do what needs to be done to fix them prior to building up the basement. If you have wall "leaks" those can usually be plugged by professionals pretty easily and not real expensively. If it is more generaly moisture, try to determine the source and then treat the source.

Check the grading!!!

Mark
 
Thanks for all your suggestions. Like I said, fortunatly, I don't have big water problems in the basement and knowing it cannot be stopped completely (nature of the beast :) I want to try and control it. Attached is the plan... I'll be doing the floor portion this weekend. I'm thinking of placing a drainage pipe (with holes) on the floor between the inner and outer walls. I can then connect a fan to one end and force air around when the humidity gets high.

Thoughts?

Cheers
Kevin.
 

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Longsoughtfor,
If its a very small (4sq') on one wall, the source should be easy to find and fix. Maybe you have a gutter downspout that needs re-routing, or one area of the outside wall that didn't get treated properly, or as Bozman stated: a grade problem. Maybe even a small leak in your water supply line or sewage line or an opening in the foundation where they enter the house. A leaking or mis-routed air conditioner condensate drain might be the culprit since it only happens in the summer. I had a shower control that didn't get caulked and a very tiny amout of water would run down the basement wall below it, but only when the shower was on and water was being splashed in that direction.

OK, I'll shutup now
 
I didn't read much of the above posts, so this may have been said... First things first... You gotta find out where the water is coming from... If it's just condensation then a vapour barrier will do wonders, but make sure there are no leaks through the walls or floor before you start building...

Joe
 
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