Almost every Ohio waterproofing decision comes down to this comparison. Interior systems are the more common retrofit; exterior systems are the more thorough treatment of the wall itself. Both are legitimate, and the wrong one is expensive in different ways.
| Factor | Interior System | Exterior System |
|---|---|---|
| What it physically does | Collects water at the footing below the slab and pumps it out | Seals the outer wall face and drains water down to a footing drain |
| Excavation | None outside the house | Trench to the footing along treated walls |
| Drainage component | Perforated pipe in stone below the slab, tied to a sump | Footing drain in stone with filter fabric, gravity or sump outlet |
| Sump integration | Essentially always required | Only when no gravity outlet is available |
| Typical cost | Generally lower | Generally higher — excavation, disposal, restoration |
| Retrofit difficulty | Straightforward on most existing homes | Constrained by decks, patios, walks, utilities and lot lines |
| Disruption | Concrete cutting, dust, interior access along the perimeter | Landscaping, hardscape and yard access affected |
| Effect on the wall itself | Wall still contacts wet soil | Wall is protected from direct soil moisture |
| Serviceability later | Pit, pump and cleanouts remain accessible | Buried; reaching a failure means digging again |
| Best fit | Pressure seepage, sound walls, tight or finished lots | Deteriorating walls, missing footing drains, new construction or additions |
Choose interior when
- Water enters at the floor line or through block cores under pressure.
- The wall is structurally sound with no significant deterioration.
- Excavation would mean removing a driveway, deck, patio or mature landscaping.
- Budget matters and the goal is a reliably dry, usable basement.
Choose exterior when
- The wall itself is failing — spalling, deep honeycombing, open mortar joints.
- The original footing drain is confirmed absent, crushed or unconnected.
- Water enters well above the footing where interior drainage cannot intercept it.
- The basement is fully finished and opening the floor perimeter is off the table.
- You are already excavating for an addition, egress window or utility work.
The honest middle ground
Many Ohio homes end up with a hybrid: exterior correction on the one problem wall — the side that collects roof runoff or sits downhill — plus interior drainage elsewhere. Surface work (downspout extensions, regrading, window well drains) is almost always worth doing first regardless of which system follows, because it reduces the load either system has to handle.
Detailed pricing for each path is on the Ohio cost page, and the full method descriptions are under exterior waterproofing.