Ideas for sealing painted basement walls

So I just moved into a new house back in July and we are finally getting settled in enough that I can start actually doing some of the projects I have on my list... one of which is to decrease the humidity in the basement.

The basement isn't "wet" by any stretch of the imagination; no water even after heavy rain, the sump pump almost never has to run except when the AC drips into it, but it's more humid down there then I would like it to be. I run a dehumidifier and that seems to do the trick, but I have plans to finish off parts of the basement and I want to make sure I seal up the walls/floor of the finished parts before I go hanging drywall ext.

My plan is to seal the floor with an epoxy coating, and that shouldn't be a problem... it's the walls that are problematic. They are already painted the the PO, and I'm not sure what they are painted with. It looks like white paint to me, but it could be drylok or some other water sealer, I have no idea. None of it is peeling or chipping anywhere and seems to be pretty well adhered to the wall (picking at it with a pocket knife does nothing to it). So my question is: what can you use to cover paint/drylok that is moisture resistant and doesn't require me to strip the old pain/drylok off the ~1600sqft of wall area like drylok says you need to do.

Any ideas would be greatly appreciated.


Edit: The walls are regular block walls FYI.

First, make a cover for the sump pump well that isolates it from the basement. A lot of moisture can be absorbed by the air in the basement. Second, tape a piece of plastic or glass to the wall and floor, 16in X16in should do it. Be sure to seal it up as best you can to the surface. If moisture is weeping through the walls or floor, you'll see beads of moisture form between the plastic/glass and the surface being tested. This should help find the problem. You may have to test all four walls.
I don't think you'll ever remove enough old paint to make a difference with the way the second coat will adhere unless you sand blast it. Do your exposed pipes have condensation on them?
I had a problem in my basement. The block walls were full of water and eventually leached thru to the basement. The wet spots never manifested to a 'leak' but they did leave a mineral deposit on the walls. I had to regrade the outside to remove my problem. Hope this helps some.
LHH

If you have drylok on the walls now that is what is used for sealing against moisture.

@ grommit: I was planning to do that just to see if there is any moisture coming through, but like I said, I don't really have a "wet" basement. I guess I'm just a little **** about things, and would rather be safe then sorry. My pipes never have condensation on them, and now that it's getting colder out it seems to be less humid in the basement, so maybe it's just that it's humid here in the summertime.

jwhcars said:

If you have drylok on the walls now that is what is used for sealing against moisture.

Click to expand...

I looked closer at the walls and I think it must be drylok on there already, not just paint. I wonder if I could just add another coat of drylok? The PO who painted the walls wasn't very careful about filling all the little crevices in the block, so I'd like to do a more thorough job of it. Maybe I'll send an email to the company (drylok) and see what they say.

Thanks for the advice.

Ventilation.

Add a whole house fan set up on a timer to run a couple of minutes per hour.

Granted there are not many block basement foundation walls around here, most people have a dehumidifier in their basement. Dump the bucket every couple of days and your basement should be dry and odorless.

a point to consider is that a basement, as well as being a living space is a mechanical access space for the first floor. Corning is doing a bang-up business with their modular basement wall systems. It will take a bit of work and thought, but I suggest modular wall systems for basements. So many people build the basement out like it is the first and second floor and then the electrician and plumber have a hell of a time modifying/updating anything that need attention. As well, I have so much deterioration behind the po installed basement walls that my wife was really happy just having freshly painted basement walls. I did a skim coat of plaster prior to painting and it looked good.

A mini-split heat pump will handle your dehu needs. If you are looking for ventilation products check out www.tjernlund.com. Their Xchanger product might be useful, depending upon your needs. I heated my basement with a Rinnai Energysaver. They have vent extensions which allow the exhaust to be brought up to sufficient level. Good luck with your project.

Step one: Find out where the water or moisture is coming from.

Do the 'tape the big piece of plastic to the surface in question (wall and floor) in multiple places and check for moisture'.

After that, you can try and address how to manage or minimize or control the moisture and humidity.

Check the grading of the yard and especially right around the foundation. Check and make sure any/all downspouts direct water away from the foundation. Make sure the gutters and downspouts are clear and able to direct water away from the foundation.

General 'best' practice is to try and direct water away from the house in the first place, and then to minimize/reduce it getting into the basement walls next. That usually means making sure the exterior of the foundation walls is 'waterproofed' or 'damp-proofed'. As well as possible exterior drainage piping to direct water away from the foundation walls.

Next, you generally don't want to 'seal' just the interior masonry walls. That would just let water soak into the porous or hollow masonry foundation and then the water wicks or travels to other places in the walls (or just stays wet or damp 'internally' and turns into a never-ending humidity or mold reservoir.

And then you may just have to run some dehumidifier(s) to manage the basement humidity. Just the way basements generally are (cooler and maybe slightly more humid because of proximity to the ground/soil and also because they generally don't have fresh air circulation/venting).

YMMV.