So I painted my basement concrete floor...

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Old 07-13-15, 07:28 PM
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So I painted my basement concrete floor...

I posted previous threads on how I am semi-finishing my basement and have decided to paint the concrete walls and floor. Rather than locking the moisture out with the use of Dry-Lok or a similar product, I used a latex acrylic that allows the concrete to breathe so if moisture did make its way in, it would evaporate and I have no regrets because there's no sign of hydrostatic pressure for the past 6-7 months since I painted the walls. Now I just painted the floors as well, but this time used an epoxy acrylic because I figured it would need to be more tough because of the foot traffic it would experience. I used a paint similar to what's used in garage floors, added speckles, and it looks really good.

However, it's been raining quite a bit here in the midwest lately and I noticed after about a day after I did a second coat on the floor and it dried, there was a small puddle that collected in the middle of it. I checked the basement ceiling (or bottom of first floor to see if a pipe leaked or something) but no such sign, so it had to come from the bottom beneath the concrete. I did patch up some cracks in that area so I guess the moisture just seeped through the cracks or the pores of the concrete.

I was going to consider adding a gloss topcoat or seal on top of the two coats of acrylic epoxy but just like the walls, I'm considering not doing this so the concrete (floor this time) could breathe through the paint and evaporate any moisture, similar to what I did with the walls. It's too bad as I really wanted that clear gloss topcoat but afraid it may cause worse problems by trying to lock the moisture out and create high hydrostatic pressure underneath the concrete floort.

What do you think guys, topcoat or let it floor "breathe" like I did the walls?
 
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Old 07-13-15, 07:44 PM
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Checked it again a couple hours later

The water spot, not really a puddle, was basically almost gone, dried out and it didn't really leave a mark. Wondering if it was just residual moisture from the paint itself, as it did go on pretty thin, but the moisture was pretty clear, not gray or anything like the color of the paint. Not sure what to do at this point, to clearcoat and help toughen the surface even more to foot traffic, or not.
 
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Old 07-14-15, 03:16 AM
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While latex coatings will 'breathe' somewhat especially when compared to solvent based coatings, they still restrict the passage of moisture. The unpainted concrete allowed the moisture to dissipate quicker and probably went unnoticed. A better moisture test would have been to tape a sq ft or two of plastic onto the concrete and then inspect it a few days later to see if it was wet under the plastic.

Because of all the moisture issues that below grade slabs tend to have I shy away from coating them with anything other than a concrete stain. Adding a sealer would definitely help the coating wear longer and clean easier but if it traps moisture you'll have more issues. I'd suggest waiting and see how it does ..... also see what some of the others have to say
 
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Old 07-14-15, 04:55 AM
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There is another source of moisture that may be involved here, humidity. A cool floor and high moisture levels in the air could form condensation and with the paint, that moisture stayed on top. Unpainted it was just absorbed as Mark mentioned.

When must allow the moisture to dry to the inside, you next have to manage that moisture, a dehumidifier. Not sure if you are running one, but a rainy day occurrence would also have high humidity. Check and monitor the relative humidity at floor level along with the temperature at the same location. Use those two numbers to determine if condensation is likely. Calculator below. The dew point is the condensation point.
Temperature, Dewpoint, and Relative Humidity Calculator

Bud
 
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