Wet Basement - Dehumidifiers?

The old farm house on our property has "always" had a very wet basement. Eventually we're figuring on getting professional help in - it's going to be challenge. (The walls are glazed terracotta block - not stone or cement block). Even now (well after the snow melt and early spring rains) there is usually damp if not downright wet spots on the floor here and there along the wall.

Anyway - in the meantime I'd like to help dry out the area and be able to store things up off of the floor without getting instant mildew or rust. Has anyone ever used a "room" dehumidifier in such an extreme environment? (Example - put down some mouse traps a few weeks ago using peanut butter as bait. The peanut butter is now a big blob of mold! [img]/forums/images/icons/tongue.gif[/img] ).

Can "dehumidifying" be too much of a good thing? The floor joists and all have been exposed to this kind of damp atmosphere for decades. If I actually do dry the area significantly with a dehumidifier - anything I should be watching for in the wood or elswhere to go wrong as it may dry?

Tim

We have the same problem in our basement. I use a standard room dehumidifier and run the discharge hose to a sump pump pit. It can be expensive to run, but the alternatives are worse as you've discovered, e.g., mold, mildew, rot.

Mike - how big of a unit are you running - and how much of a dent did it make? The basic "box" stores seem to only carry units up to a certain size (50 pints?). Not having used one before I wasn't sure if this was just spitting in the wind or a realistic effort.

timb - I'm not sure what capacity my Whirlpool is. I got it at Lowes a few years ago (it was the only model they had in stock at the time) and it pretty much runs all the time, all seasons. My guess is that it costs $50/month. Our basement is 30' x 15' x 6' tall.

I just visited the Whirpool site and the one I have looks like either the 40 or 50 pint standard model. It does a good job of keeping the basement dry, as does having sill vents that allow for air movement. In the winter, I open the register that's on our forced hot air furnace to get drier air moving around.

The only problem I have had is in winter when basement temps drop a little which has caused the coils to freeze. Then I turn it off and let it thaw.

Tim, for fourteen years we lived on the lake shore and the basement was very damp when we bought the house. The first thing I did was run extentions on the down spouts to get the rain water away from the house and install drain tile around the foundation at about three feet. That helped a lot but we still had to run three dehumidifiers to make the basement useable. We were able to put an office down there and my wife's sewing and crafts room.

In the spring all three would be running almost all the time. The sump pump would run every two to three minutes too. There was just a lot of water moving toward the lake and the house was in the way.

The house did dry out some and the hard wood floor did separate a little but it was better than all the dampness. The mold is what worried me the most. I have heard some real horror stories about mold causing a sick house.

Tim Sullivan

The wooden beams (logs) in our basement were also infested with powder post beetles. I always believed that the damp environment (previous owners did not use a dehumidifier) fostered this infestation. We had them treated, then I installed I beams and steel support posts down the middle of our basement. Installing the posts is also when I found that what I thought was a 'real' cement floor was, in fact, just a veneer. As I turned the screw at the top of the post, the foot of the post broke through the the floor. So, I got to dig 2 or 3 feet (I can't remember now, this was 25 years ago) down and pour concrete footers to support the posts.

Tim,

If you decide that you don't want to dehumidify, you could still store things in the Blue Plastic barrells that seem to be sold everywhere.

Also, there is a water proofing compound that you can apply to the inside of the walls, that is supposed to dry up basement leaks. I saw one basement that had 4" of water standing on the floor and a small spring coming in through the wall. Homeowner applied the waterproofing and a few months later, when I went back, there was no more water and no more leak. (It may have been the waterproofing, or not. But it might be worth a try.) The product is available from "Western Concrete", if you have such a place, and probably from just about any large cement supplier if you dont.

Rain gutters would probably help, as would sock tube and gravel buried around the outside of the foundation. The first rule of waterproofing: keep the water away.

Steve

The big pain in the posterior is that the entire basement is fired glazed terra cotta block. Nothing, and I mean nothing, sticks to it for very long. All of the really good inside waterproofing materials I've looked at are meant to soak into the cement / concrete block a little to get a bite and seal the pores. So I have no idea if there is anything that might go on as a skim coat.

On the other hand, morter is morter - and these blocks are glazed - so you would think that there could be something I could do for the morter joints and the blocks ought to be fairly mosture resistant. Just far more tedious than the whole-wall treatments.

With all the rain we've been having the basement is wetter now than it was in the spring melt. Standing water or at least "wet cement" over 75% of the floor (or more). [img]/forums/images/icons/frown.gif[/img]

Tim,

As Tim S. suggested, you're probably going to need to direct the water away from the basement. The first rule in waterproofing an underground house is to simply make the water run away from the building. This is usually accomplished through sloping the ground to run surface water off, installing rain gutters with extensions, and finally through footing drains. Depending on how well the soil drains and how damp the area is, I've seen one footing drain used and sometimes two, with the second one about 1/2 way up the wall.

Trenching down the outside of the foundation, waterproofing it and running a footing drain would undoubtedly be the most expensive fix.

Yeah - we'll have to start with the outside if we do anything. Sloping away isn't practical without MAJOR earth movement. The house sits with maybe 500-600 feet of 4-5% nice steady slope above it and the grade already comes within one foot of the sill. The gutters already route well away from the house.

Have to figure out a way to tell if this is mostly surface run off or if there is an underground spring(s) involved. Oddly enough the basement leaks nearly (but not quite) as badly on the "down slope" side which makes me fear water table issues. Keep hinting to the wife that "I'm afraid we're going to have to buy a backhoe" for the tractor we'll be ordering - for this and a thousand other tasks. (Like it's something I'd prefer not to do [img]/forums/images/icons/wink.gif[/img] ) Only problem with a do-it-yourself on the sill drains - I'd be afraid of having one of these walls push out and collapse when they're exposed. Might have to try a french drain a couple yards (at least) away - couldn't hurt (I don't think.)

Same problem in our house. It's over a hundred years old with a stone foundation. We have a veritable river running down there as long as the temps are above freezing.

I don't like the idea of sealing from the inside. This means that water is allowed to infiltrate the foundation walls right up to the interior surface. I'm thinking that the water would then want to flow vertically through the wall, weakening it further. Also, freezing and thawing would be a problem.

The ultimate for our situation (besides having gutters in good condition) would be to dig around the walls right down to the foundation. Seal the exterior with something (there's quite an array of products to choose from); backfill with a little gravel; lay down drain tile; landscape cloth on top; more gravel; and finally backfill. There are several additions (front porch, rear deck, and lean-to) that would have to removed to accomplish this. I don't have the resources (read cash) for this type of fix right now.

My plan, as I've seen down in many farm houses in the area, is to control the water that does get in. I'll be chipping a small trench in the floor around the foundation walls eventually leading to the sump pit. Having a thinner, deeper channel of water would seem to evaporate less readily than having it spread out in a thin layer across the whole floor.

I've seen basement "gutters" used with sumps and sump pumps to good effect. There are even commercial moldings that can be used. For now for us doing something like that - along with a strong dehumidifier may be all that's practical. I'd look into renting some type of diamond/wet power saw to cut the groove. Has to be something out there well suited for this type of cut.

Of course I'm not even sure if some of the water isn't coming up straight through the floor via various cracks - and not just from the walls or wall/floor joint.

Tim

What's your soil like? Last time I was down that way, I remember a lot of clay and rock.

Steve

Still is!

Actually I've never been down very deep on this property yet. The top soil is really pretty good - reasonably rich and not too much clay. But I've only been down about 12"-18" here and there. But just a few hundred yards to the south (and down slope) my inlaws place seems to be mostly shale under 6" of top soil. We've dug post holes by just busting up the shale with an iron pole and using a shop vac to suck up the fine fragments. [img]/forums/images/icons/grin.gif[/img]

I'm just wondering if soil type could have something to do with the dampness. If the shale bed is close to the floor of the basement, and has an underground slope that runs toward the house, water could be following along it seeking a way out. Are there any springs down slope?

Its important to remember that the slope at grade is only part of the story. There are also slopes underground caused by changes in soil type, denisity, etc. The shale would be such a change. I saw a diagram once that showed how even digging into a hillside and backfilling can affect the underground slopes. The backfill is always looser than the original material, which results in a slope. Water will follow the path of least resistance.

The outside waterproofing is probably going to be the only thing that will do you any good. You might look around to see if you can find a contractor to do it, that way you maybe can get a guarantee. Some places specialize in such repairs.


Steve

Good questions. Don't know of any springs or other evidence of subsurface aquifer flow anywhere nearby - there is a pond 50-60 yards off (downslope) but that's pretty obviously just surface fed (and drains away from the house). But it wouldn't surprise me that (given the amount of water) there is some hydraulic pressure there around the foundation more than can be accounted for by surface sources.

That would be my bet. You may also just have a high water table. It may naturally be just a few inches below the basement floor and any added rain or spring melt raises it.

Steve

Hi all,
I am living in a house for 10 years. I have never faced mold problem in my basement until now. However, last week I have found my wall in damp condition. It is covering with mold. My friend suggests me to use dehumidifier and polystyrene-backed paper. Is there any other suggestion then I really want to hear from you?
_____________________
For More Information Visit: Best Dehumidifier and Dehumidifier Ratings