Basements & crawl spaces · United States

There's water where it shouldn't be. Start by working out where it got in.

We don't sell waterproofing, we don't install anything and we have no quotes to protect — which is why we can say plainly that a wet basement is a symptom, not a diagnosis, that the cheapest fix is usually outside in the yard rather than inside the wall, and that the single most useful thing you can do costs nothing: go and watch where the water goes during a storm. Here is how water gets under a house, what each pattern means, and the exact point where this stops being your job.

Start here: where's the water coming from?

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Water insideWater on a basement floor is a symptom, not a diagnosis. The useful question is never "how do I dry this" but "where… Waterproofing"Waterproofing" covers three completely different jobs at three completely different scales, and the word alone tells… Sump pumpsA drainage system ends in a pump, and a pump is a motor with moving parts sitting in a wet hole. It is, by a wide… Crawl spaceMost of a house's moisture problems start in the space nobody goes into, and the standard advice about ventilating it… MoldMold is not the problem. Mold is the receipt for a moisture problem, and it will come back on clean wood if the water… CracksMost concrete cracks. The question worth answering is not whether there's a crack, but what shape it is, whether it's… Bowing wallsA wall that is leaning inward is not a moisture problem with a structural side effect. It is a structural problem,… DrainageBefore anyone excavates a wall or installs a system inside, it's worth checking whether the house is simply… Floor structureDamp under a house eventually stops being a moisture question and becomes a carpentry one, and the first parts to go… Air & radonAir moves upward through a house, which means the crawl space and the basement are supplying a share of what you…

Where is your water actually coming from?

Tell it when the water shows up, where it appears, what you can see, and what the ground outside is doing. You get back the causes your answers are consistent with and why, what to stop doing, which checks would confirm it — and, where it applies, the line that ends the tool rather than a recommendation: some of these findings belong to a licensed structural engineer, not to a website and not to a contractor's free inspection.

Open the tool

Featured guides

Start here Water in the basement after rain: what it usually means

Timing is evidence. Water that arrives with a storm and leaves a day later is behaving very differently from water that is always there.

Diagnosis The five ways water gets into a basement

A basement is a box in wet ground with a small number of weak points. Knowing which one is leaking is most of the work.

How it works Drain tile: what it is, and how it clogs

The name is a leftover from clay pipe. What it describes is the plumbing that decides whether groundwater reaches your floor.

Comparison Interior vs exterior waterproofing: what each one actually does

They are sold as alternatives to the same problem. They are actually two different strategies, and only one of them keeps water off the structure.

Maintenance Why sump pumps fail, and which failures you can see coming

Most pump failures announce themselves weeks in advance. The trouble is that nobody is in the basement listening.

Scope Crawl space encapsulation: what it includes and what it doesn't fix

Encapsulation is a system, not a sheet of plastic. Understanding which parts you are being offered is most of the decision.

The big argument Should crawl space vents be open or closed?

For decades the answer was 'open, always'. Then people started measuring what the incoming air was actually doing.

Where it starts Growth on floor joists: what it's telling you about the crawl space

It is not really a wood problem. It is a humidity problem that became visible on the nearest available surface.

Early signal That musty smell: tracing it back to where the water is

A smell is a measurement you happen to be able to make with your nose, and it is usually the earliest one available.

Triage When to worry about a foundation crack

Almost all concrete cracks. The useful questions are which way it runs, whether it is moving, and whether water comes through it.

Structural A basement wall that's bowing inward: what's happening and who to call

This is the one subject here where the correct advice is to stop investigating and get a professional opinion.

Do this first Grading and downspouts: the two changes worth making first

A roof collects an enormous amount of water and concentrates it into a few points. Where those points discharge decides a great deal.

Why this site exists

Search almost any question about a wet basement and the first page is waterproofing companies and foundation repair contractors — businesses that want the job. That is not a conspiracy, it is simply who bothers to write. But it means every answer arrives already pointed at a system, and it means nobody separates the cases where the honest answer is fix your downspouts and see what happens from the ones where it genuinely is structural.

The exception is the federal consumer material on moisture, indoor air and radon, which is accurate and which we link to where it is relevant. It is also written as public guidance rather than as an answer to the question a homeowner actually asked at ten o'clock at night with a flashlight, which is the gap this site tries to fill.

We do no waterproofing, no foundation work and no remediation, we are not affiliated with any contractor, and we have nothing to gain from you calling anyone. Where a link to a retailer carries an affiliate commission it is marked, and it does not change what we say.

We print no prices. What this work costs varies by region, by access and by year, and a number left on a web page ages into a lie — and in this industry a stale number is exactly what gets used against a homeowner.

And four things this site will never do, deliberately: tell you that something is mold — that is a sampling result, not an opinion formed from a description; walk you through structural repair, because a wall holding back soil is not a weekend project and excavating alongside a failing one can make it worse; give insurance advice of any kind; or write about health effects. If your concern is health rather than the building, that is a conversation with a doctor and with your state or local health department, not with a home-improvement site.