Interior vs. Exterior Basement Waterproofing
Both keep your basement dry. They do it in different ways, at different price points, with different disruption. Here is how to tell which one your house needs.
Interior waterproofing: manage the water
An interior system does not try to stop water at the outside of the wall. It collects water that gets to the inside, before it reaches your floor, and pumps it out. A drain pipe sits in gravel below the slab around the perimeter, a vapor barrier on the wall directs seepage into it, and it all runs to a sump pit and pump.
It is the common choice for an existing home because it does not disturb the yard, it works whether the basement is finished or not, and it is generally less expensive. The trade-off is that water still enters the wall; the system just handles it.
Exterior waterproofing: keep the water out
An exterior system stops water on the outside of the wall. The crew excavates down to the footing, cleans and waterproofs the wall with a membrane, adds a dimple-board drainage layer, and installs or replaces the footing drain in clean gravel before backfilling.
It keeps the wall itself dry, which matters if the wall is deteriorating, and it is often the right call during other excavation work or on a home with easy access. The trade-off is cost and disruption: it is a bigger dig, and landscaping, walks, and decks in the way add to it.
How to choose
- Finished basement, tight lot, limited budget: interior drainage is usually the answer
- Wall is spalling, crumbling, or structurally weak: exterior work protects it
- Already excavating for a new patio, egress window, or utility line: add exterior waterproofing while the trench is open
- Water is coming in one spot only: you may just need a crack injection and drainage, not a full system
- Not sure: an inspection settles it based on where and how the water enters
Often it is a combination
Plenty of homes get the best result from a mix: fix the grading and downspouts, seal the active cracks, and add an interior drain and sump. Full exterior excavation is reserved for the cases that truly need it.
What to do next
The right choice depends on your wall, your lot, and how the water is getting in. A free inspection gives you a clear recommendation and a written price for each option that applies.
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