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moisture through concrete in shop?

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  • #16
    the injection method of waterproofing [evidence is conflicting if it does completely stop RISING damp] relies on the injection of silicone oils into the porus brick/mortar/concrete block/mortar, the building reasearch establishment in the UK wanted to varify the effectiveness of this method as builders were running amock with moisture meters and scaring the hell out of householders who unfortunately new no better than to listen and purchase useless treatments of dubious effectiveness.
    they built walls in a tank of differing matirials eg, cinderblock. autocleaved areated thermal block. engineering brick, common clay brick with differing martars, old fashioned black mortar, inc hydraulic lime, lime portland cement, plain portland, sulphate resising portland and so on.
    the tank filled to below dpc to measure how the wall performed. no rising damp
    above dpc, little or no rising damp.
    it would seem according to them that rising damp in all but a few unusual cases does not exist.
    it was however found that penetrating damp does exist and 9 times out of 10 was misdiagnosed with a moisture meter,
    it was also found that walls that are cold condense water and that the wall will get damp as the water condenses, this can be below the surface and the wall can feel dry however this wet layer called interstitial dampness can move laterally through the wall depending on hydraulic gradient, it can present at the surface and result in effervescence of sulphates [white/pink fluff]
    you must take precautions on the outside to prevent the penetration of water, if not possible then tank the inside with membrane or the newer tanking cements eg

    also prevent moisure laden air access to the wall with membrane and importantly insulation to prevent condensation.[use solid insulation not rockwool or glass as it wets nicely. polyurathane is preffered over here]
    it can be difficult with below ground walls, i've even seen a hole cut through the wall and a layer of dirt mined away! by hand! [best left to professionals i reckon]
    in short, tank and insulate if you cant clear the back, injection dosent really work, injection of mineral oil does not work at all as the water is able to move it in front of itself as it progresses,
    hope you solve it, get someone in from the building department of your council to have a look, the service is usually free as they want to stamp out unscrupulous 'tradesmen' who offer ineffective treatments and no cure,
    all the best
    mark
    Last edited by boslab; 09-30-2011, 11:48 PM.

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    • #17
      For new construction, carefully applied Bituthene is probably the best treatment.

      Your case doesn't sound so severe that it's worth digging up the foundation to stop a bit of efflorescence. If there's a humidity problem, a dehumidifier with an automatic pump (seal up the garage) would likely be all you'd need.

      On edit: I've seen thick epoxy coatings stay put if there's only slight hydraulic pressure. This might be an answer to the cosmetic issue.
      Last edited by PeteM; 10-01-2011, 01:15 AM.

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      • #18
        What kind of rain gutters and downspouts do you have?

        At or close to ground level sounds like surface water which can normally be eliminated with gutters and down spouts.

        garage that's halfway built into basement sounds like a hill, and I'd guess it's the high side that's gets the deposits. Preferably, dig a trench on the high side with at least one end leading to the low side, a U with both ends to the low side would be best. Dig it 1ft w x 2ft deep, fill 3/4th with pea stone, and cover back up. If you'd rather, you can go with perforated drain pipe which will be a bit cheaper material wise, but the trench/gravel will handle more water and have a wider/deeper 'catch' area.

        Alternate, possibly the best, would be to trench at the foundation two or so feet, spray bitumen, then fill mostly with gravel or use the drain tile.

        With either make sure the trench or tile lead to a low spot.

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        • #19
          Originally posted by PeteM
          For new construction, carefully applied Bituthene is probably the best treatment.

          Your case doesn't sound so severe that it's worth digging up the foundation to stop a bit of efflorescence. If there's a humidity problem, a dehumidifier with an automatic pump (seal up the garage) would likely be all you'd need.

          On edit: I've seen thick epoxy coatings stay put if there's only slight hydraulic pressure. This might be an answer to the cosmetic issue.

          The best interior solution is probably as you suggest: a dehumidifier.

          But what about the outside? Is the landscape grade around the structure a contributor - and what about roof runoff? A variety of solutions are possible in those cases, some more painful than others.

          For a very good-quality dehumidifier, check out the Santa Fe line. I have the "Compact" model in my 700 sq-foot basement, purchased from Thermastor. American made, the price is 4 or 5 times the cost of a big-box cheapie. So far (1 year) I'm satisfied with the unit, but the price does sting:






          ---------------------------

          Currently I'm working on a master's degree in moisture infiltration into my home. I may be eligible for a Phd in the subject



          Edit: fix link above ...
          Last edited by tlfamm; 10-01-2011, 10:03 AM.

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          • #20
            I had a house with a humidity problem in the basement and white efflorescence stains on the walls. Scrubbed the stains off with a wire brush and muriatic acid and painted with the oil based Drylok. Definitely lowered the humidity but over time (maybe 5 years) the hydraulic pressure started forcing the Drylok off the walls along the bottom. Made it just pop off in large flakes, like cars used to do when rust got under the paint.

            To really correct the problem you need to address the water on the outside. Redirecting water away from the house with gutter extensions (if you don't have gutters, there's your problem) and regrading may fix the problem. Proper grading is 1" of slope per foot for 10 feet away from the house. If not, the footer drains are probably plugged up with dirt. Might be able to pressure wash them out. More likely you will need to dig down and replace them. Waterproofing the outside of the foundation at the same time will definitely fix your problem.

            Good luck.

            Steve

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            • #21
              I've heard alot of good ideas here but wanted to clarify a few things. The white fluff is on the walls, and fairly exclusively along where the outside soil level (It actually slopes up). My house is a split level type with high soil behind my house which slopes down alongside the sides of my house to level off with the driveway. So there is a rather drastic slope away from the house except for the back wall which could use some drainage or gutters as others have suggested. It is not just the back wall, as the side wall exhibits alot of this too and its soil slopes away from the foundation quite a bit.

              I see some evidence of black tar looking stuff painted on just below the surface level. In some areas I see black brush strokes above ground, that is why I think it was done at one time.

              There is also no "water" coming in, but I suspect it is water vapor as others have discussed. The garage does have some evidence of humidity problems but its usually at the height of summer heat/himidity (I need to seal my garage door better).

              I think from your responses that I should try digging back about 6inch or 1 foot until I see the black coating and then apply another sealer on the outside for the exposed portions of concrete. Preferably something clear or gray in color to match the concrete. Any tips on products would be welcomed, but I will also talk to some concrete folks locally.

              Certainly better drainage will help and I will look into that. We have alot of clay in my yard, so that isn't helping matters. The people who owned my house before didn't do crap to it in 30 years (besides plant ugly plants) so I'm playing catch-up now!

              Thanks alot guys!

              KEJR

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