5 Steps For How to Waterproof Basement Walls From the Inside

Are you wanting to know how to waterproof basement walls from the inside DIY style? In this article we will go through the 5 key steps so that you know exactly what to do from start to finish. 

Disclaimer: This article includes suggestions for preventative measures for basement waterproofing if you are not currently experiencing any water damage or issues in your basement. If you currently have cracks, leaks, flooding or any other damage, we advise you contact us immediately. 

Step 1. Time for cleanup!

You should first clean the places you will waterproof the basement walls from the inside. If there are any coatings on the surface, wall, or floor they must be removed because many of the waterproofing products described below can only be applied directly to the substrate.

With the use of a wire brush, sandblaster, or other tools, old paint can be eliminated. You must always wear the appropriate protective gear when removing paint, so please get advice from your local paint store on how to do it safely. With a scrub brush, warm water, and a little dish soap, clean the walls of dust and debris.

Step 2. Plug the holes.

The next step in how to waterproof basement walls from the inside is to use hydraulic cement to fill any holes and significant cracks that are readily apparent. Even under pressure, hydraulic cement stops water from leaking through fractures and holes in brickwork. Have a strategy before you begin if you’re using rapid drying cement because it will set and harden in only 3-5 minutes. Before the cement sets, smooth it out with a trowel.

Step 3. Fill in any visible small cracks

Cement is good for larger holes and cracks, but for smaller cracks you can use a crack filler. If you don’t have larger holes, you can get away with only using crack filler instead of hydraulic cement. With that said, we always recommend a basement inspection for holes and cracks of any size as it could indicate that something more serious is going on in your foundation that could lead to bigger and more expensive problems down the road. In which case, these steps on how to waterproof basement walls from the inside will not resolve the issue. To know whether you need an inspection, look for specific indicators.

Step 4. Seal up any and all basement openings

Look for any doors, windows and window wells in your basement, this is where you’ll need to seal. To do this, use caulking, it can easily be purchased from your local hardware store. If you’ve never done this before, and you want to ensure that it looks professional and not like your kid did it, we recommend you use these techniques.

  • Add painters tape on either side of where the caulking will go
  • Use the right type of caulking, for siding, windows and doors, polyurethane is best
  • Cut the tips off straight instead of on an angle
  • Cut the tip so that the hole tiny—about 1/16 inch in diameter for smaller cracks
  • Push the caulk into the gap instead of trying to drag it over the gap

Step 5: Finally, apply a waterproof coating to waterproof basement walls from the inside

How to Waterproof Basement Walls From the Inside

Apply a waterproof coating to the surfaces of your basement after sealing any gaps and cracks. When looking to select which product is best, consider looking for one that is guaranteed to shield walls and floors from hydrostatic pressure and water seepage. Use a high-quality nylon bristle brush or a 3/4″ nap roller to apply the concrete sealer, making sure to massage it into the masonry’s pores. To guarantee waterproofing and proper coverage a minimum of two coatings are needed. Before applying, carefully read all manufacturer recommendations and directions.

In Conclusion

Although caulking, hydraulic cement and cracks filler are popular materials for DIY basement waterproofing projects, neither one of them actually stops water seepage if you have issues with your foundation. These techniques will simply delay the damage before you end up needing to bring in a specialist.  For this reason, unless you are a professional who knows how to waterproof basement walls from the inside, it likely does not make sense for you to be the one filling the holes, cracks and caulking as it is only a band-aid solution.