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meth 09-25-2008 01:21 PM

Painting Basement Floor and Foundation Walls
Hey guys - after some great advice from slick shift and other I completed a successful painint project outside (seperate thread), now I am on to the inside. Cleaning up the basement and looking to paint the masonry walls with a sealer such as dryloc or something. Looks like the previous owners may have done it some time ago but it needs to be cleaned up. Is there any benefit to this stuff or should I just use a regular latex paint? What product do you guys recommend?

Then I will be doing the floor - its never been painted, so I will clean it up and paint it to keep it clean. Its an unfinished basement and will remain that way for at least the next 2 years so I am just trying to get it as clean as possible. I have used a product from General Coatings before in my previous house to paint the basement floor and it held up pretty good, again what do you guys recommend? There is really no water issues in the basement, as it remains dry, nothing else to scrape up, seems pretty basic - just want to use the best and most durable coatings - I would rather stay with latex than oil since I am concerned about the odor and although the basement is dry, the dampness in a typical basement must mean oil would take forever to dry.

Matthewt1970 09-25-2008 08:47 PM

What you want for the floor is actually called "Basement & Concrete Floor Paint" and it comes in Latex. They claim it is good for a garage but it's latex so don't use it in your garage, or atleast don't park a car on it.

If your walls were already painted once, then DryLok won't help except in any cracks. Pretty much any old latex paint will do.

Nestor_Kelebay 09-25-2008 09:31 PM

I think you would do well to wait until this coming spring and cover large parts of your floor with clear plastic. Slide a hygrometer under the plastic and tape the edges down. If moisture is coming up through the concrete, then the hygrometer will show an increasing relative humidity under the plastic until it reaches 100% and condensation starts to form on the underside of the plastic. That way, you know for sure that you do or don't have a moisture issue with that floor.

To get the best service on a floor, you want a paint that dries to a HARD film. Take some plastic laminate sample chips and sand them down so that paint will adhere to them. Take them, and some Q-tips to your local paint stores and use the Q-Tip to paint a bit of whatever people recommend onto your laminate samples and allow to dry. Go to wherever they sell the latex product recommended in the last post, have them shake up a quart of the stuff and use a Q-Tip to paint a laminate chip with the stuff.

Also, have a quart or gallon of a polyurethane floor paint shaken up, and paint a laminate sample chip with polyurethane floor paint.

Give the samples a month to dry completely (and probably crosslink in the case of the latex paints) and then draw a line on all of them with a 6H pencil and a firm hand. Maybe line up all the samples and draw a hard line across them all with a firm hand and a ruler to ensure that you have uniform pressure on the pencil point on all samples. Erase the marks and hold the samples up to a light so you can judge the depth of the mark, and see which one is hardest as evidenced by the shallowest indentation in the paint left by the pencil.

That will determine the hardest drying film available to you, and hence the best choice (all other things being equal) for a floor paint.

You can paint concrete walls with anything you want provided the concrete is more than 2 years old. Ditto for floors. Neither needs to be primed before painting.

If it wuz me, I would paint the walls (if they're rough) with a concrete block filler to smooth out the roughness to make for a more civilized looking wall. Either that, or set fake bricks on those walls and call them "finished".

Nestor_Kelebay 09-25-2008 09:39 PM


You said: "and although the basement is dry, the dampness in a typical basement must mean oil would take forever to dry."

You've got it bass ackwards.

Humidity in the air will slow down the drying time of latex paints, but won't have much effect on oil based paints.

What determines the rate at which water or mineral spirits evaporate from latex or oil based paints is something called "fugacity", which can be thought of as partial pressure. Since there is no mineral spirits in the air inside a steam bath, oil based paint should dry just as fast inside a steam bath as it does in a boiler room (say) of the same temperature. The humidity would slow down the rate at which water evaporates from latex paint, but not how quickly mineral spirits evaporates from oil based paint.

Similarily, if you were to pour out a few gallons of mineral spirits onto a basement floor, and then light a cigarette while you paint the walls with an oil based and a latex paint, the high concentration of mineral spirits in the air would slow the drying time of the oil based paint, but not the latex paint.

In chemical engineering, computer programs that predict the compositions of the liquid and vapour phases in things like distillation towers at oil refineries or liquid/vapour separators in other chemical plants do so by equating the fugacity of each chemical in the liquid phase with that same chemical in the vapour phase. When the fugacity of each chemical is the same in both the liquid phase and the vapour phase, then you theoretically have equilibrium where each chemical is evaporating from the liquid into the vapour as quickly as it is condensing from the vapour back into the liquid. I took a evening course on this at the U of Calgary, and to the best of my recollection, the method we used to write a simulation program (that never worked) DID NOT take into account the amount of the other compounds. It presumed that the other compounds in the liquid and vapour didn't affect the equalibrium of each compound. I really don't know how good an assumption that is, but if it's a reasonably good one, then humidity shouldn't affect the drying time of oil based paints.

slickshift 09-26-2008 05:17 AM

If the walls were drylocked, and it's still working, there's no benefit to another coat
It can be painted over
If the walls were drylocked, and it's failing, perhaps you'll want to re-drylock
It's not easy stuff to work with by any measure, so don't take the re-drylock lightly

Technically, there's a bit of durability advantage to oil floor paints
But any floor dampness, seasonal or no, can peel up the oil pretty quick
Today's quality "latex" floor paints (Like Ben Moore or Rustoleum) are pretty close in durablity....close enough to go with what you feel comfortable with

I'm not familiar with General Coatings and how they compare, sorry

meth 09-26-2008 07:54 AM

Thanks for the feedback - great to hear from you guys, I am certainly getting an education and appreciate it! I will take the advice and proceed. The Dryloc that is there has not failed, just yellowed in color over time. I did pick up a gallon of it to do a section and see what it was like to work with - to me its like painting with elmers glue, very thick and not easy to apply. I think I will proceed with a quality Ben Moore latex instead. As for the floor, will take the advice of Slick and Nestor and proceed as well. The next project will be the garage floor and finding a paint that won't peel up from hot tire pick up!

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