Concrete Slab Foundation/Some Dampness/Need Flooring Advice

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vh2665

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Dec 17, 2011
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Hi,....First time poster.

I've got a situation here in Gulf coastal Texas and need to get a good feel for what my options are. Quick description is this: We had extensive foundation leveling done recently, the carpeting which had been in place for decades was ripped up and discarded, and now we're noticing varying signs of dampness on the concrete where the carpet used to be. It is unknown whether this was always the case or if this had something to do with the foundation work. Foundation Contractor has been called about this, downplays it as either normal condensation or a plumbing issue outside his realm of work. I've aired this on one other internet forum and they all tend to be very alarmist, stating basically that I'm up a creek without a paddle short of having thousands and thousands of dollars at my disposal for more work requiring extensive digging.

...So this site has caught my eye as probably more of a specialized flooring discussion board and I'm hoping to lay out a more detailed description of what's going on in the interest of a 2nd opinion.....Here goes: We've noticed that on high humidity days since our foundation work was done, that the uncovered concrete slab/floor tends to get darker and generally look "damp". At first, we were suspicious of plumbing lines having been cracked during the house leveling but have talked with a plumber (not the same company as the foundation people) who tended to downplay this possibility. The connection to the dampness seems to be directly related to atmospheric humidity after studying the situation for approx. 2 months. We live less than 10 miles from the Gulf of Mexico. The worst that the dampness has been was one afternoon when four individuals had used the shower one right after another, the dishwasher had been used for two loads right after another, and the weather outside was "soupy"....humidity bordering on fog and rain was on its way. The concrete was dark and, within the tiny depressions of its surface texture, you could sometimes catch the sheen of water if the light was right. I ran my hand across this area at this time and there was barely - but definitely - dampness bordering on wetness.

Now for the complicated part... We are living paycheck to paycheck except for lower-end-of-five-digits sum I inherited recently which we'd hoped to use to make some modest repairs to this small house. It's never been the local garden club house of the month and it's never going to be -- the sheetrock is cracked, the grandkids' scribbles adorn the walls, there's a missing area of stop moulding in the doorway to the kitchen where a refrigerator had to be "manhandled through" a decade ago and this has been roughly patched over with wood putty,.....some areas of the fence outside have had to be reinforced with wire mesh "sewn on" with baling wire......you get the picture.
My question is basically this: Are the nay sayers who are warning us about attempting to put down any kind of floor on top of this slab coming from the point of view that complications might get real ugly from a cosmetic standpoint or is the real deal such that we might somehow (1) run a considerable risk of rendering our house uninhabitable by putting down a floor in this present environment, or (2) run a considerable risk of whatever floor we might decide to put down becoming "ruined-beyond-even-poor-people-such-as-ourselves-being-able-to-use-it within 10 years as a result of this amount of dampness I've described? Thanks in advance for your answers...
 
I heard some crazy thing about Texas. Everytime I home is bought it must be leveled. That can cause enourmous problems with slabs.Did you have a plumber do a pressure test?

You need to check for dewpoint. Read this here. http://www.buildwithbps.com/assets/downloads/resources/Dewpoint Chart.pdf A thermohygrometer would be needed in your house for this, plus an accurate temp of your slab.

Then there are ways to block moisture from ruining floorcoverings. But best bet is to find out whats going on first, treat it if need be, then find the appropiate breatheable floorcovering.
 
What all was done to level the house? Was the leveling limited to the foundation, or was the slab leveled also?
Does the outside ground slope towards the house or away from it? Are you in a low area or close by any water................... areas where a high water table might be an issue?

If you ripped out the old carpet yourself, was the concrete perfectly dry? Did any of the tack trips have rot or heavy rust on the pins? (aside from pet urine or areas known to have gotten wet)
 
Haven't had any pressure testing done...just the foundation work which involved the contractor busting up the slab at 5 different points in the center interior of our house and digging down approx 3-4 feet followed by some adjustment involving a powered jack and placement of concrete objects to hold the slab at a particular height (??). The holes were then filled in with dirt and capped over with a patch of concrete. There was a severe drought in our area this year and a lot of homes had trouble.....it was a long time getting the contractor out to our place. We're sitting on what I've heard referred to as "gumbo clay soil" if this has any bearing on any of this. The ground around our house seems to slope away from the house at a very gentle grade and we're about a quarter mile from an inlet of Galveston Bay which is just off the Gulf of Mexico. Never have had any house flooding other than what I'm told was knee high water 50 years ago (our house was probably just a few years old at that time) during a hurricane (Carla). We've been here since 1994 and have seen a couple of tremendous rains but nothing that ever got water into the house. The tack strips from where the carpet was pulled up seem to be in "fair" condition but there is considerable rust on the tacks themselves. I need to mention that the slab sustained some pretty substantial cracking during the leveling process recently.
 
Listen to Ernesto, he is a concrete guru. And yes it may be a possibility if not probability of needing to spend more than you want to.

Improper choices may well lead to unusable even unhealthy floors and/or conditions.
 
my advice to you would be one of patience---moistness in a time of high humidity is a lesser concern than moistness in a time of low humidity--here in the northeast we refer to that condition as winter---do you have winter in texas?if its still wet when its dry out then you have new water--unsure of your groundwater sea level situation but i heard you been havin a bit of drought so maybe its a water pipe issue---it could also be water from the curing cement--plastic taped to the slab overnight --checking for moisture underneath the next day will tell you that---is there any chance that its bubbling crude?---texas tea? you could change your name to derrick and move to bevery hills---but seriously you need to determine if its new water or old water--hows your water pressure?
 
That part of Texas that isn't sand is clayey/sand and moves considerably and always will. The Houston/Galveston areas are known for their high humidity year round basically. Concrete will always draw any moisture that is or becomes available.

I would say it has always been like that and the carpet over the years has allowed for the natural moisture migration to the surface of the concrete as the moisture naturally seeks to evaporate.

It would not be advisable to ever use any floor covering that must be glued in place, it won't last. No wood for sure, no wood-core laminates, no vinyls.

Basically this leaves only two types of floor covering. Either more carpet (recommended) or ceramic tile. Ceramic tile would be compatible due to the type of adhesive that is used to install it.

You could run dehumidifiers all the time if you don't already but that won't fix the issue it will only facilitate the removal of a little more moisture.

There are claims being made by some sealer manufacturers that their product will seal-in moisture but those claims are arguable. Nothing has worked so far.

Probably the first thing to do is to have some calcium chloride testing done to determine exactly how much moisture is really present at the time of the testing. That also won't change anything but it will confirm your suspicions and offer a means of measuring the presence of moisture.

The rusty tackless nails indicate this has been going on for a long time.

Lanscaping can have some effect but if the concrete is drawing moisture more from the relative humidity then the landscaping may also not do very much.
 
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Haven't had any pressure testing done...just the foundation work which involved the contractor busting up the slab at 5 different points in the center interior of our house and digging down approx 3-4 feet followed by some adjustment involving a powered jack and placement of concrete objects to hold the slab at a particular height (??). The holes were then filled in with dirt and capped over with a patch of concrete. There was a severe drought in our area this year and a lot of homes had trouble.....it was a long time getting the contractor out to our place. We're sitting on what I've heard referred to as "gumbo clay soil" if this has any bearing on any of this. The ground around our house seems to slope away from the house at a very gentle grade and we're about a quarter mile from an inlet of Galveston Bay which is just off the Gulf of Mexico. Never have had any house flooding other than what I'm told was knee high water 50 years ago (our house was probably just a few years old at that time) during a hurricane (Carla). We've been here since 1994 and have seen a couple of tremendous rains but nothing that ever got water into the house. The tack strips from where the carpet was pulled up seem to be in "fair" condition but there is considerable rust on the tacks themselves. I need to mention that the slab sustained some pretty substantial cracking during the leveling process recently.

I highlighted my concerns in red................. how many percent of the floor and how may square feet were involved in each of the areas you mentioned?

Just trying to figure out how much new slab you have. A lot of slab, or just hole patching?

It can easily take a few months for a new slab to dry out depending on a lot of issues.

One issue I wonder about is, was the concrete pumped in, or poured in using a wheel barrow?
If pumped in, they might have added a lot of additional water which can mean a lot of extra drying time................ and I'm not speaking just a few extra days.
 
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I don't understand your construction methods but here in New Zealand polythene is laid on the ground then the concrete slab is poured on top.

By your contractor busting up the slab at 5 different points in the center interior of our house and digging down approx 3-4 feet followed by some adjustment involving a powered jack and placement of concrete objects to hold the slab at a particular height (??). The holes were then filled in with dirt and capped over with a patch of concrete.

Here in NZ I would guess that if that happened here there would be a moisture problem around those holes as there would be a break in the poly letting moisture through due to hydraulicking from any area surrounding the house. The old story of the swimming pool popping out of the ground
I could be barking up the wrong tree intirely as I am not sure how your construction is done :)
 
Theres some houses near me that have large clay deposits under them as well. Nothing but trouble, they move, break up the slabs and hold in tons of moisture.

Still I would like to know at what point do you see evidence of water on the surface and the dewpoint, temps and rh at that time. And was your hvac going at that time and for how long?

After pressure checking and everything is OK there my next step would be to perform both CaCl testa and ASTM F-2170-11 relative humidity tests.

Ceramic tile can handle lots of MVER but it can also pose a problem with the thinset curing and setting. In which case I would use Ditra.
 
Thanks all for your feedback!

@ rugaddict.... What we call Winter here is "picnic weather" according to relatives from New England...lol. It might get to barely freezing here less than 4 or 5 times a year. I think the record low is around 18F. The rest of our winters involve a lot of damp 40-ish to 60-ish days interspersed with some days that approach 80.......mostly damp-ish but some clear days where the static electricity bites when getting in or out of one's vehicle. I will be taping down some plastic shortly as you suggested to gauge the moisture on this slab/floor.

@ incognito... Will look into this product but am extremely strapped, financially and don't want to be putting Rolls Royce parts on a '63 Dodge Dart so to speak. Also, I'm getting about 4 responses to every 1 response to my particular predicament saying that I can forget about any type of after-the-fact sealer staying put. The video about application strikes me as somewhat of an upper scale product but I will check it out further and thanks very much for taking the time to post this.

@ BudCline... Thanks very much for the geographical specific info as that is indeed our area. The more I'm finding out, the more I'm thinking we'll be going with carpet again.

@ highup... I'm terrible with numbers but the house is 1300 sq. ft.....1 story, 3 bdrm/1 bath late '50s construction brick exterior with a one car garage which was converted to a den sometime prior to 1994. No central heat or AC......multiple window unit ACs and a wall furnace in the central hall. There were five interior digging sites with this last foundation work, three along the length of a central hallway which measures approx. 17' long by 3.5' wide. There were two interior digging sites in the adjacent living room which measures 13.5' x 12.5' which lined up with the ones in the hall along the center axis of the house running the long dimension. All five of these digging sites were capped with wheelbarrowed in concrete and an average measurement of these caps is about 40 inches by 28 inches. There was also 5-7 digging sites along the front exterior and front/side exterior of the house done concurrently with this latest foundation work and some if not all of these exterior sites were readjustments of foundation work which was done around 1994. I don't think any of this exterior digging required breaking up of the slab. Upon finishing this latest foundation job, the contractor told us that there was an extremely small deviation from being perfectly level that remained but he believed that his crew had reached the limits of what could be done without causing an unacceptable level of cracking of the slab and that the slab had indeed cracked in several places during the job. On a later visit to our house due to concerns of the floor/slab "looking like something out of a battle zone after our expenditure of X thousands of dollars" he indicated that the floor did have what he referred to as a "little belly" and that it would be a relatively easy fix with some sort of self leveling substance to ready it for flooring either with carpet or something along the lines of Pergo.....
 
"Theres some houses near me that have large clay deposits under them as well. Nothing but trouble, they move, break up the slabs and hold in tons of moisture.

Still I would like to know at what point do you see evidence of water on the surface and the dewpoint, temps and rh at that time. And was your hvac going at that time and for how long?" (Ernesto)

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As I understand the question, It was somewhat cooler than normal on the day we noticed the worst moisture and I would say with 95% surety that none of our window unit ACs were running nor the wall furnace down the hall from where the moisture was most evident. I have set aside a notebook in which to log the temperatures and atmospheric conditions present whenever we notice this area looking damp but I hadn't started this on the day the really alarming dampness caught our attention. It was probably between 55 and 65F outside and there was an atmospheric frontal boundary associated with a fair amount of rain headed our way at that time.......very overcast bordering on fog the day of the worst dampness on this slab/floor as I remember. There have been several more instances of a "dark, perhaps damp looking, slab" since then but nothing that involved a "very slight but visible sheen of wetness" as was the case with the worst occasion approx. 1 month ago.
 
That info helps a bit, but I was wondering all of why this was done. Was the old slab and foundation breaking and cracking, or the home needing to be jacked up and re-leveled or both?

Being as old as the home is, I doubt there was a plastic vapor barrier under the slab.......unless you know otherwise.
Jon mentioned what will happen when the slab surface is cut into, leaving lines where ground moisture can more easily migrate to the surface.

How long ago was the work completed? Concrete will "cure" in one months time, but it won't be totally dry in that period of time..... it could take months to dry out to whatever it's final condition will be, especially so being it's an inside concrete pour, unlike a concrete slab on a new home, which is exposed to the sun and wind for a good length of time.

I'd say carpet would be best option. It's certainly cheapest route.
 
That info helps a bit, but I was wondering all of why this was done. Was the old slab and foundation breaking and cracking, or the home needing to be jacked up and re-leveled or both?

How long ago was the work completed?


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The foundation contractor was called in because the "foundation had moved" to such a degree that our front door was frozen in its frame and there was a lot of new cracking/buckling at places in the drywall. There had been severe drought conditions and practically every house on our block had foundation work done this year as a result. The work was completed 51 days ago as of this writing. Our mind is pretty well made up at this point to go back with carpet pending a tad more assurance (a consultation visit from a carpet installer or two) that our environment is a go for it.
 
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The foundation contractor was called in because the "foundation had moved" to such a degree that our front door was frozen in its frame and there was a lot of new cracking/buckling at places in the drywall. There had been severe drought conditions and practically every house on our block had foundation work done this year as a result. The work was completed 51 days ago as of this writing. Our mind is pretty well made up at this point to go back with carpet pending a tad more assurance (a consultation visit from a carpet installer or two) that our environment is a go for it.

51 days isn't very long.......... the surface can even be dusty and still be way to wet for most floor coverings.

I read that for concrete to dry (not cure), 1 month per inch of concrete placed. This link says that too. It's approximate of course, depending on conditions.
http://www.cement.org/tech/cct_drying.asp
 
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The foundation contractor was called in because the "foundation had moved" to such a degree that our front door was frozen in its frame and there was a lot of new cracking/buckling at places in the drywall. There had been severe drought conditions and practically every house on our block had foundation work done this year as a result. The work was completed 51 days ago as of this writing. Our mind is pretty well made up at this point to go back with carpet pending a tad more assurance (a consultation visit from a carpet installer or two) that our environment is a go for it.

51 days isn't very long.......... the surface can even be dusty and still be way to wet for most floor coverings.

I read that for concrete to dry (not cure), 1 month per inch of concrete placed. This link says that too. It's approximate of course, depending on conditions.
http://www.cement.org/tech/cct_drying.asp

From that link.
The amount of concrete moisture can be considerable. In practical terms, several pounds of water must evaporate from every square foot of concrete for the slab to be considered adequately dry for floor finishes. An industry rule of thumb for estimating the drying time necessary for concrete floors to reach acceptable moisture content is 1 month of drying for each inch of concrete thickness (1 mm per day).

Drying begins when water is no longer available at the exposed surface. If concrete is moist cured by sealing in the original mix water with wet burlap or plastic sheets, drying will begin when these covers are removed. Spray-applied curing membranes are somewhat breathable, and therefore, drying begins shortly after the membrane is applied. However, curing compounds can drastically reduce the drying rate and significantly extend the drying period.
 
FWIW:
There are geographical regions in Texas where underground irrigation systems are installed around the perimeter of a home (not unlike lawn sprinkler systems) in an effort to control and stabilize the natural subsurface clay's. This way the extreme expansion and contraction of the soils is maintained [in check] throughout the year.

I doubt that any run-of-the-mill carpet installer is likely to be well versed in any of the hydration techniques used these days. But, ya never know. I think I would consult first with a local soil engineer and get his opinion of what can and can't be done in your area and what conditions would be anticipated under what circumstances.

I'm not convinced that the use of DITRA over a slab in a high moisture environment is a good idea but that's just my personal conviction. That's not to say using DITRA wouldn't produce satisfactory results. I just don't know.
 
I like Bud's idea of stabilizing the soil. Trouble is also with to much water of course. Not much you can do to stop that cept gutters and grading and that still won't totally solve the problem.

These builders I was working for thought they had the problem solved, used 10 inch thick slabs, engineered all tied together with rebar and plastic vapor retarder. Still cracked, and I mean some big cracks!

I told them the neighborhood directly to the north had a serious problem with clay deposts and the builder/developer got sued, class action. But they got the land cheap! lol
 
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