Do I need anything more than drylok in my basement?

Question

I'm trying to finish a room in the basement. The plan was to frame some studs, hang drywall, the usual procedure when building a room. The thing is, it might be out of budget to buy everything I need for that while keeping everything moisture free. The studs, the insulation, the vappr barriers, flooring, etc.

My question is: could I not just drylok the cement walls and floor? Insulation and heat loss isnt really a big problem for me. I could just drylok the walls so it looks painted and put a rug down for a simple room right?

I should also add that there haven't been any moisture problems in the past. I just don't want to create any new mold problems.

Answer 1

I would not install any vapor barrier in a basement. If you do paint the walls make you use a paint that will allow moisture to transpire through the wall.

Mother Nature has an unlimited supply of moisture so there is no way you can prevent it from entering the basement. You just want to make sure it is allowed to dry to the inside. If you trap it with a barrier it will cause mold, mildew and eventually fail.

Read the articles on this site regarding vapor barriers. Especially in basements. Like this article from fine homebuilding reprinted here. The number one mistake is "One: Vapor barriers on basement insulation will rot your walls".

I would just paint the walls with a flat latex and stain the floor. Or you could stain both and let the walls breathe even more.

Edit from tahwos' comment below: Should probably add the benefit of properly graded exterior slope, back-fill that can drain adequately, and working gutters, to round out this answer. A correctly installed and maintained basement, is a dry basement.

Good luck!

Answer 2

Do not Drylok the floor using the original or extreme waterproofer - it will fail, it's not durable enough for floors. You can use Drylok Clear (might have been renamed Drylok Floor and Walls, or else that's just a similar product by Drylok that my store changed to recently) for the floors, or a penetrating concrete sealer such as RadonSeal.

Don't use Drylok on hollow block walls without drilling weep holes into the voids in the bottom course of blocks, or any water that makes its way into the block will exert hydrostatic pressure on the thinner walls of the block, potentially causing failure (it takes a lot less pressure to break 1" thick concrete than 8" thick concrete). Please note that the weep holes will admit water into the basement, if necessary, but this can reasonably be arranged to be below the parts of the wall susceptible to water damage. Drylok is fine on poured concrete walls.

If you have no history of moisture issues in the basement, you can forgo the Drylok - vapor barriers will be cheaper and easier than proper application of Drylok (which requires thorough cleaning, acid etching, and at least two coats with coverage of only around 100sqft per gallon (1/4 that of normal paint), according to its instructions). I'd recommend poly sheeting if you have humidity concerns, although it's probably better to just run a dehumidifier - even with sporadic moisture problems my dehumidifier keeps the humidity in the basement below 60% in the summer. If you just want a slightly finished look, you can absolutely just paint the wall.

Answer 3

To be clear, the understanding of vapor barrier is to understand the difference between vapor and water.

Vapor is small molecules of moist air. Any void will allow moisture to flow into the foundation. Usually this is because warmer air contains more moisture than cold.

A dry sponge allows water to be drawn into it's dry fibers. Air-conditioning creates a vacuum like pull that will attract the moisture. If your exterior foundation waterproofer allows moisture from sub soil this moisture will be drawn to the voids with in the cmu blocks. Once the cavities fill up the ac will pull the moisture inside the basement. To avoid this you should drylock the cmu blocks this will help keep the arid moisture habitat within the cmu block walls. 2nd you should always have voids like frame your basement walls at least 1 inch from any exterior block or concrete wall. 3rd adding Rockwood insulation will help reduce any moisture collection. Adding a 6 mill plastic interior barrier between the framing and drywall will allow for negitive pressure within the wall. Your ac will dray against the drywall and will not be able to suck the moisture into the room.

This process is also similar to I stalling closed cell phone panels on the exterior walls. Framing walls and installing drywall.

Foam over walls prevents the arid moisture laden air being pulled through the walls in this example the air barrier is facing the drywall. The vapor barrier is facing the block or concrete wall.

Hope this explains the issue. Doing nothing, painting with latex and plastic over touching concrete block walls are not adequate and if your a contractor you will be liable for repairs.