There is no single repair by that name — there are about five, each matched to a different entry point. Picking the wrong one is why a basement leaks again.
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Waterproofing a basement: inside, outside, or neither
"Waterproofing" covers three completely different jobs at three completely different scales, and the word alone tells you nothing about which one you are being sold.
Managing water is not the same as blocking it
The single most useful distinction in this subject is between keeping water out and giving water somewhere to go. They sound alike and they are opposites.
Exterior waterproofing is the first idea: excavate down to the footing, clean the outside of the wall, apply a membrane. And put in drainage so water never touches the structure. It is the most thorough approach and it is the most disruptive. It means digging out the perimeter of the house. And it lives or dies on what is in the way (a deck, a driveway, mature planting, a neighbor's property line).
Interior drain tile takes the opposite view: water is going to reach the wall. So intercept it at the footing inside, run it in a perforated pipe under the slab and let a sump pump lift it out. Nothing is being blocked; it is being routed. This is why a system like this is inseparable from the pump. The drain is only as good as the thing at the end of it, which is why sump pumps get their own section here.
And then there is the third category, the one that fills hardware store aisles: waterproof coatings and masonry paint. These have a real and narrow use. They resist dampness and vapor moving through masonry. What they cannot do is hold back water that is under pressure. If groundwater is pushing on the outside of that wall, a coating on the inside is a film with the whole weight of a saturated yard behind it. It fails, and it usually fails after it has hidden the problem for a season.
There is also an honest answer that nobody selling a system will lead with: sometimes the correct fix isn't waterproofing at all. If the water is arriving because the ground slopes toward the house and the downspouts discharge at the foundation, the cheapest effective work happens outside, in the yard. And it belongs in the drainage section rather than this one.
Waterproofing guides
One blocks water at the outside face, the other collects it at the footing and pumps it away. The choice is usually decided by what's above the wall, not below it.
Perforated pipe in washed stone at the footing. Simple until it silts up — and a clogged drain tile behaves exactly like a basement with no drainage at all.
Same pipe, different job. One moves surface water across a yard; the other intercepts it at the footing. Confusing the two picks the wrong fix.
The membrane is the least of it. Excavating around an occupied house is usually what decides whether this job makes sense.
Contractors use the word for sealing a crawl space and for wrapping a foundation wall. They fix different problems, and the quote rarely says which.
Gutters, drains, injection, coatings and pumps each fit a different cause. Matching the fix to the cause is the whole job.
Dampproofing, waterproofing and drainage are separate layers, and many foundations only have the first.
A basement, a crawl space and a slab get wet differently, so the same fix does not carry over.
A coating slows vapor. It cannot hold groundwater pushing from the other side, and that decides whether the can is worth opening.
Water rarely crosses the middle of the wall. It gets in at joints, pipe holes and the footing, so the work belongs there.
Once a crawl space is sealed, insulation moves to the walls. The vapor barrier and the water fixes have to come first.
Clean, patch, coat: the order that works for small cracks and damp patches, and the signs that sealing is the wrong move.
One slows moisture, the other resists liquid water. Why the words get mixed up in quotes, and the three questions that sort them out.
Floor, walls, vents and air: the four parts of a complete job, and the gaps that turn a full job into a partial one.
Start with the water outside the wall, then the cracks, then anything that needs a contractor.
Ground, walls, vents and air: what the word covers, and when a crawl space is worth closing.
Stop the source, dry fast, decide what stays and what goes, then rebuild. The order matters more than the materials.
Leaking, cracking or moving: three different problems, and only one of them is a sealing job.
A thin layer resists moisture, not water pressure. Where a coating belongs in a plan.
Condensation, seepage or a leak: a two-day test and a few notes tell them apart.
Collect at the footing, pump it out. What an inside system protects and what it leaves alone.
Damp air, seepage, a point leak or movement: four problems, four different repairs.
A British word for lining the walls. What it is, where it falls short, and the US equivalents.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.