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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4 unit building-water issue

I have a 4 unit building, each unit has a basement. only one unit has a sump pump. it never runs, however the unit next to it always takes water along one exterior wall. drainage and downspouts are all sloped 10' away from building. Time to call professional? Could drainage tile be broke or need cleaning?

Wet basement -Concrete walkway built around the house

Hi, I have exactly the 'not-to-do' concrete pathway built 3ft away from the house. the soil between the pathway and the house is about 5" lower than the pathway, creating a 'swimmingpool' around the house! so yes, it's definitely not good! but i don't know how to fix the problem because:

1) the pathway actually isn't leveled, it looks like it's sloping towards the house.

2) the pathway is quite high, it almost levels with the bottom siding of the house, so even if I fill dirt up between the pathway and the house, the dirt cannot be graded much away from the house, it will most likely 'level' with the pathway.

I'm totally stuck, am I suppose to deolish the pathway completely? or should I put more concrete to extend the pathway to the wall of the house?

Very Knowledgeable and a good

Very Knowledgeable and a good advice in preventing water damage in the basement. thanks

leaky cellar

My cellar is very old and is not under my house. It is not a basement. I have poured concrete around it to keep the water away but it still leaks up the wall about a foot and through a couple of cracks on the floor and on the bottom 3 or 4 steps . This yr we had lots of rain. On the outside it is surrounded by concrete at least 8 ft. and more in other places. I am wondering about the grading. I need to do some around my house but I wondering if it will help with the water table. I have fought this for 20 years. I have tried to waterproof it on the inside but that doesn't work. Everybody wants to put a drain in it but I'm not fond of that ideal. Or they want to put the drain against the wall that funnels it to a sump pump. It just seems like there should be another way. Any suggestions would be appreciated? Thanks Rita

Awesome article

We had leakage in 2 of the walls of our basement. The first line of defense as usual was to call the waterproofing companies - EverDry and Aquaguard. Both gave me estimates in the thousands with work consisting of sealing the walls and digging the concrete basement floor and installing pumps. I then happened to read this article (Thanks Tom) which was really useful. During the next rain, I observed there were several holes in the flexible downspout extensions which created puddles in exactly the 2 places where the basement walls were leaking. In one place, the gutters were leaking too. So, we replaced the 5" gutters with 6" gutters and put in new downspouts and extensions. The leaking problem never came back.

Tom, this is just the

Tom, this is just the information I was looking for about waterproofing. My husband and I have been thinking of waterproofing our basement. These tips are just what we need to get started! I will have to show this to my husband. Emily Smith 

Basement Waterproofing

My basement constantly has issues flooding. There are stairs leading down to the basement door, and water really seems to collect around the door. I wonder if there is a way I could use gutters in order to re-route the water a different direction. 


These methods to help waterproof a basement are so simple, I can see why some people would be skeptical. Sump pumps are great tools, but they shouldn't be the first line of defense when it comes to waterproofing. Like the article says, keeping gutters running freely and sloping the soil away from the home, it keeps water from being in a place where it can enter the home, thus keeping it dry. 

water proofing contractors

Oh so that's how someone would water proof their basement. Would this be something that a water proofing contractor would recommend doing? As a first time home buyer learning about water proofing certain areas of my house has been somewhat new for me. 

Where to begin?

I have discovered a hole in my basement floor. I'm concerned it could be foundation or a broken clay drain. Would you call a plumber or waterproofing expert? Or both? It's a hole about the size of half dollar. It's located a foot away from the wall and about 6" away from an old toilet drain that has been plugged for years. The house was built in 1920 and has a damp but not wet basement. When I look into the hole I see loose concrete sand and a gap from the floor. I just don't know where to start. Thanks.