Poured foundations, which are made of concrete, are often used to create a sturdy, dry basement. They are, however, not immune to water damage. The foundations of these homes can be affected by water damage, including cracks, leaks, and mold.
This case study is a tutorial that explores an example of waterproofing the concrete foundation of a Midwest-style home. It gives insight into the most effective techniques, materials, and strategies for homeowners and contractors to plan more efficiently.
The Problem – Basement Dampness In Recently Built Homes
Just two years into their new home in a suburban Illinois area, a couple began to see moisture around the base of finished basement walls. The poured-concrete foundation did not show any visible signs of structural damage. However, the persistent dampness and a musty smell were alarming.
After an on-site inspection, hydrostatic pressure caused by heavy spring rains and inadequate drainage was found to be the culprit. Water was being forced out of the concrete pores and the minor cold joint, saturating the interior, and the homeowner lost their investment.
Step 1: Diagnose and Plan
Before beginning any waterproofing, an inspection was done. The assessment focused on:
- Terracing slopes and soil grades
- Gutter performance
- Perimeter drainage is a good idea for homes.
- Interior signs of condensation and seepage
The foundation was confirmed to be in good shape, but the exterior waterproofing system was not. This is common for older buildings that are reliant on interior drainage and damp-proofing systems.
Step 2: Exterior Excavation (and Surface Preparation)
To make the waterproofing process most effective, access to the outside of the foundation was necessary. A crew dug up the soil surrounding the perimeter to expose the entire height of the concrete wall.
Includes key preparation steps:
- Power-washing your foundation walls will remove any debris or soil.
- Sealing minor hairline scratches with hydraulic cement
- Allow surfaces to thoroughly dry before applying waterproofing products
This is important because surface contamination can reduce the performance and adhesion of waterproofing materials.
Step 3: Apply Waterproofing Solution
Once the walls and foundation were fully exposed, cleaned, and re-plastered, the team installed a poured concrete foundation waterproofing. It included:
- Membrane Liquid Rubber: This is a roll-on or spray-on elastomeric material designed to cover cracks and resist long-term water intrusion. The flexible material allows for future wall movement.
- Dimple Membrane (Drainage Board): This protective barrier sits between the membrane and backfill. It allows water to flow downward rather than putting pressure on the foundation wall.
- Footing Pump Installation: Install a perforated tile at the base of the excavation and connect it to a sump pump system. This will ensure that water can escape from around the base of your foundation.
This approach combines active and passive moisture protection to address both current leaks and future moisture risks.
This guide to concrete foundation waterproofing provides a comprehensive look at the process.
Step 4: Backfilling & Final Grading
The team then backfilled the excavation after the system passed inspection and dried. They used clean, compacted earth. The slope of the grade at the house was slanted away by a 5% degree to avoid surface water pooling on the wall.
Downspouts also extend to discharge water a minimum of 6 feet away from the foundation, a step that is often forgotten but very important.
It’s A Dry Basement And Peace Of Mind
The two spring seasons following installation saw the basement remain completely dry, despite both experiencing above-average rain. The humidity normalized while the musty odor vanished. The homeowners said that not only was their basement more comfortable, but they also felt more confident in using it for a longer-term investment.
The Lessons Of Homeowners & Contractors
This case illustrates some important conclusions:
- Avoid relying on only minimal damp-proof coatings. These are not designed to resist hydrostatic forces.
- Prioritize exterior solutions, if possible. They address water before it even enters the system.
- Proper gutter and grading management reduces the load on waterproofing systems.
This is a reminder for contractors that they need to educate customers on the importance of long-term safety, not just temporary fixes. Homeowners are reminded that waterproofing can be an essential investment, not just cosmetic.
Conclusion
The goal of waterproofing a poured concrete foundation is to keep the basement dry and preserve structural health. A layering, exterior-focused strategy is often more effective when planning a new building or addressing leaks.
Understanding your property’s soil, climate, drainage, and other conditions is essential. Consult with professionals who will tailor solutions to suit your individual needs. With the correct methods, materials, foresight, and planning, you can ensure that your home’s foundation will remain watertight and solid for many decades.
