By: Kate Sheridan
There's no reason to endure a leaky, wet basement when you can waterproof your basement yourself, usually working from the inside out. Use these techniques for effective basement waterproofing on your newer home, to supplement the job your contractor's done or to catch seepage and foundation cracks before they do serious damage.
What You'll Need
- Work gloves
- Wire brush and paint remover (to remove latex paint)
- Commercial waterproofing powder or compound
- Epoxy sealers, boat epoxy or hydraulic cement
- Chisel and hammer
- Paint brushes and water bucket
- Trowel
- Industrial-strength hand wash
Tips
- Wear old clothes and a work hat.
- If your hair is long, tie it back.
- Since your hands will be dirty, cemented or sticky much of the time, an apron with pockets is handy to keep tissues, cell phone, extra brushes and other small items you might need during this process.
- Use a movable shop light to add extra illumination to the area to ensure you track down all cracks and tiny holes.
Find and Repair Small Leaks and Cracks
- Locate and repair cracks and wet spots. Feel along the length of your basement wall for holes, cracks and wet spots. If you see moisture on the walls or the floor, trace it to the source. If it's dry, old places where moisture entered will appear as streaks of dust or dirt on the walls.
- Remove any latex or oil-based paints, because most waterproofing mixes won't stick to that material. Use a stiff wire brush and a commercial paint removal liquid to take off the paint. Clean and dry the area thoroughly.
- Use a hair dryer to completely dry any areas showing dampness or seepage.
- Use a brush-on epoxy sealer to seal porous spots and hairline cracks in walls.
Repair Larger Cracks and Fill Holes
- For larger cracks and holes, clear out all loose material from the damaged area.
- Use a chisel and hammer to undercut the edge of the crack, making it slightly larger inside than outside, in order to ensure that your patching compound gets a good grip from the inside out. Use this undercutting technique especially where the wall meets the floor, if there's dampness at that juncture.
- Follow the instructions for using hydraulic cement, epoxy or boat glue to fill the cracks and holes. Typically, you'll mix up the compound, form a paste and pack it tightly into the crack, smoothing excess out and away with a trowel. For smaller cracks, epoxies should get the job done. Use hydraulic cement for larger breaks. Don't use water-soluble materials like plaster or spackle, as these will dissolve when they get wet.
- When working at the floor-wall seam, make the undercut large enough to form a trench into which you'll pour or place your waterproof cement.
- Quick-setting cement often requires that you allow the patch to dry, then wet it and smooth it again before applying a second treatment. Check your manufacturer's instructions.
- When you're working with deep cracks, don't try to patch everything at once. Use two or three thinner coats for the best adhesion. Smooth the material out when you get to the surface, feathering it out a bit from the crack. Be aware that some patching materials will set in 15 minutes or less and that you may not be able to sand or smooth them once they've dried.
If Water is Actively Flowing or Leaking…
- In some cases, your foundation may be actively leaking water. If this occurs, use waterproof cement and apply it by hand.
- You'll make a mound of the compound and hold it between your two clasped hands for about one minute to warm it up.
- Push the compound, hard, into the leaking hole or crack, from the bottom up, and keep your hands on it until it sets in place, stopping the flow of water. This may take a few minutes and more than one application. Repeat until the flow of water has stopped.
Apply Two Coats of Waterproofing Material
- After repairing all leaks, cracks and holes, make sure the surfaces are clean and dry and free of latex paints or flaking concrete paints.
- Use a clean brush to apply the waterproofing material to the foundation wall, always beginning at the bottom of the wall at the floor-wall seam.
- Work bottom to top, right to left, carefully applying the waterproofing material according to manufacturer's instructions. Be certain to examine each section carefully to ensure you've covered every crack and hole.
- Consider using a heavy-duty epoxy sealer on the most obvious weak spots, then recoating those spots with regular waterproofing compound for a double seal.
- Allow the first coat of waterproofing application to dry thoroughly, leaving no residue or stickiness to the touch.
- Always wet down the first dried coat and allow the moisture to seep in and dry again completely.
- Before applying the second coat, make sure the wall is thoroughly dampened a second time, as most waterproofing compounds must be applied to a damp wall.
Keep a close eye on your newly waterproofed basement during the next few heavy rains, and note any places where seepage or leaking erupts, then repair that area again.
In most cases, this interior sealing and waterproofing will stop leaks and correct wet basements. If water is being forced into your basement by extreme water pressure from the outside, you may need to consider hiring a contractor to retrench and reseal the exterior of your home's foundation.
