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AU_Prospector 04-06-2010 03:29 PM

rainwater in crawlspace

Purchased home in the middle of a major drought in the SouthEast United States 3 years ago. When we inspected under the home in the crawl there was absolutely no evidence at all of water.

This winter was especially wet. Also there were many storms of several inches of wind driven rain from the south and the west. Around Christmas I went under the house for no real reason, but I am glad I did. In the South West corner of the home there was about two inches of standing water in a low lying area of the crawl. Also there was a 3 inch pond of water about 6 feet wide surrounding a support pylon in this area as well. I have been under the home several times since and the ponds have gone but the concrete blocks on the south and west sides of my crawl are damp and have that 'wet concrete' look about them. Should I be concerned?

There is a very gentle slope into the home from these directions, no way to avoid that. Its a slope of about 2 feet per hundred, thats a 2% grade. All other sides are graded away from home. All rainwater is diverted to the street. Crawl is packed clay with a plastic vapor barrier. The ponds were flooded onto the plastic. Any thoughts appreciated.


Nestor_Kelebay 04-06-2010 07:15 PM


Buried around the foundation of your house will be a perforated pipe called a "weeping tile".


This drawing shows weeping tiles around the footing of a basement wall. Where you live, there may be a different kind of drainage system, which is commonly used in your area other than weeping tiles. You'll have to check with your local plumbing inspector or phone up some building contractors to see what's used in your area.

The whole purpose behind weeping tiles is to allow excess ground water saturation to drain into the weeping tile (and on to a sump pit or basement floor drain). By removing he excess ground water around the house, you eliminate the hydrostatic pressure that causes the ground water to migrate INTO the basement walls. Thus, if the weeping tiles are working properly, there is no hydrostatic pressure in the ground water causing it to want to penetrate into the basement wall.

Excessive moisture, masonary and freezing temperatures don't mix. Moisture alone won't cause damage to masonary. Freezing temperatures alone won't cause damage to masonary. It's only when you combine excessive moisture inside the masonary with freezing temperatures that you have serious problems. That's because water expands as it freezes, and the result of water inside masonary freezing is called "spalling" where the surface of the masonary breaks off in "chips".

This is what spalling in concrete looks like:

In this picture, however, it's more likely that the spalling was caused by corrosion products forming around the rebar and building up enough pressure to pop the surface of the concrete off.

Where spalling is caused by freezing water, the process is similar. It's just that the expansive force that causes the concrete to break away in chips at it's surface is caused by the expanding of H2O as it freezes rather than the accumulation of rust around the rebar. The spalling will look the same, but it'll be caused by different mechanisms.

If you don't see any spalling, then you haven't had an real damage so far. Still, I would check to see if you have weeping tiles around your house to carry away excess ground water, and if so, you might be able to get someone to run a video camara into your weeping tiles to see if they're all plugged up with mud.

AU_Prospector 04-06-2010 07:55 PM

Hey thanks for the post. I dont think I have seen sparring but I will check again. I should clarify that my foundation is concrete cinder block, not poured concrete like you describe. I will say that when it rains hard the runoff flows just below the surface. Our soil is about 2 to 4 inches of top clay on a hardpan type of subsurface some call chert which is not very permeable. The rainwater will ooze along this layer trying to find the low points which is why I described the slope of my yard. I will check for this tile you describe, I have never seen this. I have heard of 'french drain' or 'curtain drain' which is installed after the construction if there are problems. Do you think I might need this? I live in Georgia, the ground does not freeze most winters. If it does, the frost line is only a couple of inches deep.

Wuzzat? 04-06-2010 08:17 PM

AU for gold, right?

I guess you could level the area somewhat so you get a large surface area and the water evaporates as fast as it collects, depending on your air humidity/temp levels.

Or, a French Drain might actually work but I've had no luck with them.
You could first check your soil permeability in winter by digging a small hole, filling it with water and timing how long it takes to empty.

Lastly you could use the smallest pond pump with a water level switch, maybe all running on 12 v or 24 v, and pipe the water elsewhere. Your 6' 'pond' contains about 20 gallons, minus the underwater volume of the pylon.

AU_Prospector 04-06-2010 09:21 PM

That's right, gold!

Hey is it okay if I do nothing at all? I mean is it par for the course given my extremely poor clay hard-pan soil and the occasional monsoon Georgia rain that I get puddles of standing water in my crawlspace every once in awhile?

I see no evidence of mildew or powder mold in my crawl. The only indication of moisture beyond the darkening of my cinder block foundation is my pink fiberglass insulation in between the floor joists is getting stringy in places. Do you know what I mean? It kind of is separating and hanging down like cobwebs because of the moisture weight I guess.

Wuzzat? 04-07-2010 07:21 AM


Originally Posted by AU_Prospector (Post 43235)
. . .is it okay if I do nothing at all?

Good question.
If the house was designed to last its 50 year lifetime with [chronically?] moist soil under it, I guess "Yes."
But how moist is too moist?

itsreallyconc 04-10-2010 04:24 AM

doing nothing at all is the your right as its your home,,, if it were a rental to you, would you be so accepting ?,,, no one thinks standing wtr's a good idea especially near supporting columns which weren't designed for your existing condition.

we're in marietta & repair those problems :welcome: maybe we'll talk personally some day when you inquire about repairing sags :D good luck til then !

ps - there's a reason cinder blocks aren't used anymore AND why we replace them w/concrete !

AU_Prospector 04-11-2010 07:09 PM

Dude, I wouldnt let you anywhere near my home and the reason why is your attitude and your PS message. Your PS is pure BS in my opinion and obviously I know nothing about it.

I live in a neighborhood of custom homes built by various builders mostly in the 2700 to 4000 square feet range, the oldest being about 8 years old the newest are still under construction. EVERY SINGLE one of them have cinder block foundations on top of concrete footings so in my book your blowing smoke.

itsreallyconc 04-11-2010 07:26 PM

' Dude ' ? ? ? that's ok - but ck on the difference 'tween cinder block & CONCRETE block,,, again, know of no bldr using cinder blocks anymore down here nor in nj / ny,,, not even certain the apron stores sell 'em,,, we'll install a system in a home up in lake arrowhead this week - concrete block - leaking wtr - classic !

near the sandy spngs marta station, there's a complex w/conc blk bsmt walls over conc footings - same w/2 condo groups off johnson ferry near the hooch,,, your homes're probably the same.

far's attitude, ck yours - we'll still be working !

AU_Prospector 04-11-2010 09:05 PM

RU kidding? Your breaking my balls because I refer to Concrete Block as Cinder block? I thought this forum was for amateurs. If you want a pro forum go find one. As far as I know the words are interchangeable. Like Cola and Coca Cola. Man, get a life!

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