How to Waterproof a Finished Basement

Basement sign

To effectively waterproof your finished basement you must solve any drainage issues on the outside of your basement walls. Installing a drainage system around the exterior of your house's foundation is the best way to prevent a wet, damp or leaky basement. Although this is easier to do when the house is under construction, you can still install a drainage system after your house and basement are completed. You should also add gutter extenders to your downspouts to carry water away from your house.

Things You'll Need

• Ground sheeting
• Gravel
• Downspout extenders
• Topsoil
• Portland cement
• Pump sprayer
• Polymer-based sealant
• Plastic piping with holes
• Shovel
• Work Gloves
• Wheelbarrow

Instructions

1. Excavate a deep trench all the away around the walls of your house. Dig down passed the foundation to the footings. If possible dig the trench out to an area in your yard where water can drain. However, make sure you don't drain any water into your neighbor's yard.

2. Inspect the foundation walls to see if there are any cracks or holes in the walls. If you find any, mix some Portland cement with water according to the directions on the package and use a trowel to apply the mixed cement to holes and cracks.

3. Call in a professional to repair any cracks that are more than hairline in size.

4. Pour polymer sealant into a pump sprayer; spray the solution all over your foundation walls to protect them from moisture.

5. Install a layer of ground sheeting on the bottom of the trench and shovel a few inches of gravel on top of the sheeting.

6. Lay plastic piping with holes along the base of the trench on top of the gravel. The pipe will help to divert accumulating water in the trench out and away from the walls of your foundation.

7. Fill the trench up to about a foot from the top with another layer of gravel using the shovel. Lay another layer of ground sheeting over the gravel.

8. Cover the sheeting with topsoil. Plant suitable vegetation in the topsoil if you wish.

9. Attach gutter extenders to your down spouts and direct them away from your house.

Tips & Warnings

• Wear work gloves to protect your hands.

References

• WetBasementWaterproofing.com waterproofint your basement
• Natural Handyman: Q & A With Natural Handyman
• AsktheBuilder.com: Exterior Foundation Wall Waterproofing
• National Waterproofing Systems: Exterior Waterproofing