Basement Waterproofing Tips

Basement leaks are easy to prevent and even fix without taking a bath

In the 20 years I spent as a professional home inspector, the top three problems my home-buying clients were concerned about can best be summed up this way:  water, water and water!  Waterproofing your home is the surest way to make sure buyers stay interested.

While leaks through roofs, pipes and basements are constant concerns, a wet, leaking basement always ranked highest as the home improvement problem most likely to send buyers running for the nearest open house. 

Whether you are a buyer, seller or owner of a home, wet basements are always a concern. Not only is a wet basement unusable, flooded foundations can be seriously weakened and toxic mold--the newest threat to residential indoor air quality--can fester faster when an ample supply of water lies just underfoot.

3 steps to stop a wet basement

The good news about these unplanned indoor pools is this: while wet basements are often thought of as one of life's biggest home repair headaches, they are generally easy and inexpensive to fix. Yes, that's right--easy and inexpensive!

The wrong way to waterproof a wet basement.  Ask 10 people how to fix a wet basement and you're likely to get answers that include use of jackhammers to break up basement floors, backhoes to dig out dirt from foundation walls, sump pumps that have to be wired and plumbed, and other such drastic and expensive measures.

While these solutions may seem to make sense, they all attempt the impossible: to seal a foundation so tightly that it will somehow hold off water like a boat. Well, unless your house is a house boat, it won't float, so you might as well stop thinking about all the ways to keep it from doing that.

Most people blame a wet basement on a high water table, the natural level of water in the soil under the building site. This is another myth, because homes are not built below water tables. Builders attempting such a feat would find themselves constructing a foundation in a muddy mess. Likewise, basements that flood after a storm are never caused by rising water tables. A water table moves slowly and seasonally. If basement leaks show up after a heavy rainfall or snowmelt, the cause of your problem is far easier to spot and to fix.

Most basement leaks can be traced to trouble with the drainage conditions around the outside of the house. If  too much water is allowed to collect in the soil around the foundation, it will naturally leak into the basement through the walls, or even up through the center of the floor.

The waterproofing solution lies in improving these drainage conditions, which is easy, cheap and highly effective. Here's where to begin...

Good gutters.  Roof drainage is, by far, the number one cause of basement leakage. Since roof surfaces are as large as the house, they collect lots of water in heavy rainstorms. What happens to that collected water can mean the difference between a wet and a dry basement.

Properly designed gutters should have at least one downspout for every 600 to 800 square feet of roof surface. Gutters must be clean, because dirty gutters fill up and the water overflows directly to where you don't want it: near the foundation. It's also important to make sure the ends of the downspouts are extended to discharge at least four to six feet from the foundation. Spouts which discharge too close to the foundation are like big fire hoses blasting water into the basement.

If your yard and local building laws permit, one of the best ways to control roof drainage is to discharge downspouts into solid PVC plumbing pipes that run underground and release water to the street or to another low-lying area. When making this improvement, be sure to pitch the pipe slightly toward the discharge point to avoid backups. Also, don't attempt this with the soft, flexible black pipe that landscapers like to use around flower beds, because it's easily crushed and cannot be snaked clean like PVC plumbing pipe can.

Sloping soil.  Next to gutter problems, the angle of the soil around the foundation perimeter can also cause wet basement woes. The soil should slope away from the house to keep rainfall from collecting against foundation walls.

The angle and type of soil are also important. The soil should slope downward six inches over the first four feet from the foundation wall. Thereafter, it can be graded more gradually but should never allow water to run back toward the house.

If grading needs improvement, use clean fill dirt (not topsoil) to build up the soil around your house. Tamp the soil down to the correct slope and finish with a layer of topsoil and grass seed to prevent erosion. Or, just use stone or mulch. Whatever the top layer is, be certain the slope is established with the fill dirt, or else the water will just run through the more porous material and into the basement. Also, don't use straight topsoil for the grading improvement. This kind of soil is too organic and will hold water against the foundation, which is the opposite of what needs to be done.

It is also important to avoid landscape treatments that hold soil close to the house. A brick, stone or timber landscape edging around flower beds adjacent to foundation walls may look attractive, but these edges can prevent water from draining away from the foundation and increase your risk of basement flooding.

Following these simple guidelines will solve 99 percent of wet basement blues. These waterproofing improvements are inexpensive and can usually be done yourself or with a little help from your friends.

Avoid panic-peddling waterproofing contractors.  If you've ever thought about hiring a so-called waterproofing contractor to fix your wet basement, don't. Basement waterproofing contractors can often be rip-off artists that attempt to scare homeowners into an expensive drainage system when they're usually not needed.

Several years ago, one of my home inspection clients attempted to fix his leaky basement by calling in waterproofing contractors. Besides telling him his foundation would crumble without a waterproofing system, they offered quotes ranging from $7,500 to $20,000. These were outrageous expenses, even if the system did need to be installed,which it didn't.

Instead, following an inspection, we were able to instruct him on how to correct his outside drainage and easily fix the wet basement problem for under $500--and he avoided getting the soaking of a lifetime from a waterproofing contractor! 

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Basement waterproofing

You know one way you can waterproof your basement? Have a backup plan! We can plan all we want for a disaster and put in extra basement protection, but you know that one day, your basement is going to flood. I recommend people get shurflo pumps and that way they'll know how to avoid a knee-deep mess!

Basement Waterproofing

Taking care of your house is one of the most important things you do. A crack in the basement foundation can lead to bigger and bigger problems. I know people who have tried to do basement waterproofing themselves and it has been a nightmare. If the crack isn't sealed correctly, then you have to grind off whatever you put on to seal it and start over. I personally recommend that you hire a professional. It's your house, it's worth a few dollars more to be sure it lasts.


SO many people get so agitated and paranoid from watching home remodeling shows like Holmes on Homes. Of course a lot of what he says is true, and I don't doubt his approach a a contractor, but let's face it, a lot of the time he does unnecessary work for the drama of television. In almost every case of a leaky basement they are digging up the dirt from around the foundation and drilling down into the cement to fix a plumbing issue and then doing their fix. It is in many cases too much! I do agree with the fact that if home inspectors did a better job during pre-build then a lot of these headaches would not be an issue.

Basement Waterproofing

No, Basement waterproofing is not that expensive, but yes to do it the right way, you should dig it out and apply a waterproofing cement product to the exterior of the basement wall. Then you backfill in 2' lifts, compact thoroughly as you come up with a jumpin jack compactor. When you get about 2' below finished grade you layer road subgrade material or Type II, sand & 3/4" rock mix. Compact this layer well, as before, then your native soil. I have installed "french drains" around the perimeter as well to be on the safe side, which daylight out away from the basement. Yes every basement condition is different and not all basements need this application but to do it right, you should apply a waterproof product to exterior of the basement wall. 

Water in ktchen

The rear of my kitchen is a stone wall adjacent to a slate patio. The slate sits on sand. The floor of the kitchen is lower than the level of the slate. When there is an extraordinary rainfall (more than two inches), water seeps through the stone wall. This happens less than once a year but when it happens, it is a mess to clean up and the water seeps into the basement, making matters worse. Your description of the problem is accurate in terms of water moving towards the house. I can't prevent this given the landscape and the position of the house. Would a slotted pipe or "french drain" outside the house make sense? I could put it under the slate and direct it to drain away from the house. How would I find a reliable contractor to do this?


I used to go scrambling for the stand pipes whenever we had a hard rain but I found these floating stoppers (only $15 each) that you easily install in the tile directly under the floor drain. When the water comes up the stopper rises and cuts off the water flow into the basement, the rest of the house's plumbing acts as the stand pipe to relieve pressure. They work even if I'm not home, best $30 I ever spent.

basement leakage

To Tom Edwards: Despite the authoritative tone of your comments, you are dead wrong. I have 34 years and more than 18,000 full fee-paid home inspections to tell you that, while you obviously are not in doubt, you are certainly in error, and completely in error. If I were wrong on this subject, I would have long since been sued into oblivion. You simply do not understand this subject.

basement leaks

If you expect to prevent ground water intrusion into a leaking basement by only regrading the soil and draining guttering away you will probably be mistaken. I have over 20 years experience as a licensed general contractor, former building code inspector and as a licensed home inspector with over 15,000 inspected properties. Expecting to correct a leaking basement with these relatively inexpensive corrections is like stopping a boat from leaking by repainting everything from the gunwales up, or above the water line. Regrading and guttering correction will help but will not absolutely solve the problem of basement leakage.
If the walls are leaking it is because of a breech in the water proofing barrier on the exterior of the foundation. It's that simple. Water proofing contractors prefer to cut the floor slab and install drainage on the inside simply because it is typically easier than disturbing plantings and attachments on the exterior wall. The water proofing contractor will provide for a positive outlet for water entering the breached foundation wall so that there is no build up and any moisture entering the foundation wall has a clear and free outlet to a discharge basin or outside the dwelling. Don't paint all water proofing companies with the same broad brush. There are real professionals doing this work.
It's always annoying to hear a real estate agent tell a potential buyer that guttering repairs and regrading will "fix" the leaking basement. If they truly believed that they should offer their own personal performance warranty to the buyer for assurance. They won't do that and that says it all.

Beware of blanket statements that only apply to you

Not sure how you can apply your solution to everyone's problem when every situation is unique. In fact, your reply would be better written if you added "for me" after every sentence. Starting with the simplest and most cost effective solution and working up from there is sound advice. Why jump to the most expensive option first? If you end up hiring a waterproofing contractor, so be it. But if your car doesn't start in the morning, start with the battery, not the engine.

basement leaks

My basement wall is made of cinder blocks and water was seeping through the walls. Since listening to the money pit. I have cleaned my gutters, repaired any leaks in them and and built my soil up so that it was sloping more away from my house. I can honestly say it's been 2 weeks and my walls are currently not seeping and it has been raining. Great tips!