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Wet Basements

This consumer guide outlines the various causes and the variety of available remedies for wet basements. The guide is designed to ensure that you know the issues, are able to evaluate advice you receive from contractors, and feel confident about undertaking a solution before the water damage becomes too severe.


A house built in the 1970’s or earlier is likely to have only minimal water protection around the foundation. Construction techniques have improved over the years, so that today’s new homes are more resistant to water, but wet basements are still a big problem. As homes age, their waterproofing systems break down. Even well-designed systems can ultimately fail. Therefore, most houses eventually have wet basement problems. Keep in mind, though, that some basement moisture problems stem from condensation rather than leakage, which will be discussed later in this guide.

The need for prompt action.Wet basement problems can range from mildly annoying to completely catastrophic, depending on the flow of water and how “finished” your basement is. Regardless of the severity, the problem will only get worse: a wet basement is something that you should address promptly.

The damage done. Dampness and musty odors are the beginning. Mildew can quickly damage furnishings. Everything from steel to cotton decays quickly in a damp environment. The bumper crops of mold and mildew may aggravate the health of someone with respiratory problems. Termites and other pests thrive in the moist dark spaces of a damp basement.

The big fear. The world abounds with horror stories about problems people have had with the process of waterproofing their basements. Price-gouging, scare tactics, high pressure sales practices, and remedies that don’t work are all quite common. This guide will help you understand the issues involved, the tradeoffs involved, and what to watch out for. Don’t let fear get in your way.

Ignoring The Problem

The most popular response to a wet basement or dampness is to ignore the problem and hope it will go away. Often people dismiss their problem as being the result of one super-duper rain storm. Unfortunately, we get those several times a year! It just seems easier to think of the rainstorm as being a once-in-a-lifetime phenomena than it is to face the fact that the basement has problems.

Ignoring the problem for a short period won’t be too calamitous if your basement is unfinished and you have stored items up off the floor. On the other hand, when you sell the house, you will have to deal with the wet basement: why not deal with it now and regain the full use of your basement for your remaining years in the house? Besides, in the day-to-day flow of life some of that stuff you have carefully stacked up out of harms way will start settling and shifting and eventually work its way to a place where it can get wet. It may be getting moldy just sitting right where it is.

Most people underestimate the damage that dampness can do to metal, fabric, wood, and other common materials. Water tends to wick up many materials so that things off the floor also get wet. Fabrics, books, wood, and other materials soak up moisture from the air.

If you plan to postpone resolving the problem, get as many possessions as possible out of the basement. What is left in the basement should be a foot or so off the floor. Plastic shelves work well because of their invulnerability to water. Part of the reason you want things so high off the floor is to promote good air circulation, especially at the walls, to minimize mold and mildew. For the same reason, you should spread things out in the basement so that air can flow freely. A de-humidifier and an auxiliary fan can get things dry and keep them that way between episodes of wetness.

While these steps will minimize the damage from the dampness, they are not long-term solutions. The problem usually gets worse and worse. Initially you have a wet basement twice a year, then you have a problem four times and year, then ten times a year. As the situation deteriorates, you will find it a losing battle to get things dried out. If you don’t move the things remaining in your basement, you are likely to find them damaged or ruined.

Meanwhile, other less obvious problems are growing. You will inevitably get more mold and mildew, especially distressing to anyone with allergies. The mold and mildew will seek opportunities to spread to bathrooms, kitchens, and other moist parts of the house. Wood beams and supports may rot at a higher rate, becoming increasingly ideal habitats for termites and other pests. Door frames are often the first wooden structures to rot out completely.

The moisture can also undermine your foundation. As water flows through the walls and floor and the soil under and around them, it slowly erodes channels. Over time, these cavities in the soil get larger and allow ever larger amounts of water to pass. This in turn accelerates the erosion problem. Left unsolved, it can undermine the foundation, aggravating settling and cracking problems. Sooner or later, you must take care of the problem. For most people, sooner makes the most sense.

Condensation Versus Leakage

If you do not have obvious flows of water after each rain but have persistent dampness, your problem may be condensation rather than water leaking through the walls. If dampness seems to be a hot-weather problem, condensation is the likely culprit.

What is condensation? The warmer air is, the more moisture it can hold. Conversely, when air cools, it often has to release moisture. The dew on your lawn in the morning is moisture that was in the air until overnight temperatures dropped to the point where the air could not hold all of that moisture. The same thing happens when warm summer air loaded with moisture comes into contact with your glass of iced tea: the glass cools the air, causing the air to give up some moisture as water droplets on the outside of your glass. In your basement, condensation develops when you have relatively warm, moist air contacting the cool surface of the walls. As the walls cool the air, droplets form on the walls and you’ve got a damp basement.

A do-it-yourself test for condensation. If you think condensation might be the problem in your basement, there is a simple test. Securely tape a 10″ x 10″ piece of plastic wrap onto the basement wall in an area where you have noticed dampness, sealing the edges of the plastic wrap with the tape. Check on the plastic over the next few days. Eventually you will get moisture: if the moisture is on the wall side of the plastic, you’ve got a leak; if the moisture is on the room side of the plastic, you’ve got a condensation problem.

Condensation Solutions

Condensation problems are usually easier to fix than leaks. Depending on the circumstances in your home, you have several lines of attack, all of which are designed to reduce the moisture in the air. Excess moisture commonly comes from clothes dryers, clothes lines, showers, cooking, and dew.

Sources of moisture.Concentrate on potential sources of moisture in or near the basement. If you have an indoor clothes line, consider moving it outdoors (at least in the warm summer months) or increasing air circulation (more on that later). Check your dryer to ensure that the exhaust vent doesn’t leak and has an unobstructed path to the outdoors. If your dryer exhaust is equipped with an energy saving switch, allowing you to exhaust air indoors or out, ensure that yours is set to outdoors and see if it takes care of the problem.

While uncommon, moisture sometimes comes from plumbing leaks. As you are checking your basement, be on the lookout for signs of a plumbing problem. One place to check is the pipes in the ceiling directly under the kitchen sink. Another problem location is the drain line that removes water from the indoor part of your central air conditioner. Some new high- efficiency furnaces have a drain line as well. If these lines are clogged or broken, they can put out a surprising amount of water.

Exhaust fans.If there is a basement shower that gets a lot of use, install an exhaust fan that draws the damp air out of the house. Should these measures fail to resolve the problem, and you are rather certain that your problem is condensation, check moisture sources in other parts of the house. In very well insulated houses, even small amounts of moisture can be problematic. The kitchen and every bath should be equipped with a working exhaust fan. Make sure household members use the fans! (If you have trouble getting cooperation on this front, have the bathroom fans hooked up to the light switch. Whenever the light goes on, so does the fan.)

Air circulation. If the condensation is quite modest, and there are not obvious sources of excess moisture, increasing air circulation may resolve the problem. Some basements don’t have air-conditioning vents, but it is usually a simple matter to create a couple of vents. If you already have vents, make sure they are open.

If your basement is so packed with stuff that air can’t circulate anyway, additional vents will have little effect. You should get rid of some junk and create air passages around and between things. You especially want air to be able to flow easily along walls. If you do not have a central fan or air conditioner, or if it doesn’t seem to adequately stir the basement air, you might want to run a circulating fan in the basement for a few hours each day. While it won’t remove much moisture, it helps distribute the moisture evenly and eliminate damp spots.

Insulation.Another approach to the condensation problem is to reduce the extent to which moist air contacts cool surfaces where it can condense. With this approach, you insulate exposed duct work, pipes, and walls – anywhere that water tends to condense. If the moist air can’t reach the cool surfaces, it won’t release water as condensation.

Leaky Basements: Battle Of The Experts

In most homes with wet basements, condensation is not the main problem. The walls are leaking or the floor is leaking. One reason people hesitate to address the problem is that there is too much conflicting advice. Much of the advice is biased, and some of the technically good advice isn’t practical. This guide should help you understand the issues so that you can make the best use of the various experts and the services available to help you.

There is a tendency among the contractors in the field to disagree with each other as to the best waterproofing method and, as a result of that disagreement, to label each other “quacks.” There is a reason for this. If you’ll read on, you’ll understand why and you will be in a position to evaluate the advice you get.

Leaky Basements: Solutions

There are essentially three general approaches to resolving a wet basement problem: controlling surface water, sealing basement walls, and installing drain systems. Each has merit, and you may find yourself using elements of all three approaches. Each approach is discussed below.

Controlling surface water. In general, the measures you take to control ground water are also beneficial in solving or preventing a host of other problems. However, while these measures alone usually substantially reduce wet basement problems, they cannot assure you a dry basement.

This is one of the points of departure between two schools of thinking in the industry. Most inspectors and engineers focus heavily on ground water control methods because they address the core of the problem. Most waterproofing companies focus lightly on these methods because they are labor intensive, messy, time consuming, and (most important) they cannot produce guarantee-able results. Both sides are right. You should undertake these measures to control ground water even if you plan to take other measures now or in the future.

To get a handle on the surface water issue, think about your house, your lot, plantings, and even the neighborhood as a system for managing rain water. Rain falls on houses, patios, trees, walkways, etc. Where it falls determines how it is channeled. Be aware of the paths and channels rain water follows, and modify those channels so that as little water as possible concentrates in the soil around the foundation. There should be no standing water anywhere in the yard.

Controlling ground water involves: a.) roofs, gutters, and downspouts, b.) grading, and c.) window wells and stair wells.

a.) Roofs, gutters, downspouts. You do not have to be an engineer to evaluate the way your roof, gutters, and downspouts perform. The best way to evaluate their performance is to put on a raincoat and go out during a heavy downpour. See what is happening. The water should flow down the roof and into the gutters, and from the gutters out the downspout to a spot draining away from the foundation of your home.

If water is getting behind your gutters, either your gutters have pulled themselves away from the board they are fastened to (the fascia) or your shingles weren’t installed with enough overhang into the gutters. To remedy the latter, install a drip edge. A drip edge is simply a piece of metal mounted on the edge of the roof to prevent water from curling underneath the edge of the roof and bypassing the gutters. Gutter repairs and drip edges are usually handled by roofers and by firms specializing in gutters.

If your gutters are overflowing, they are either clogged, too small, or improperly sloped. Keeping your gutters clean is one of the easiest and most practical ways to reduce ground water around your foundation. Gutter specialists, roofers, landscapers, and chimney sweeps may all clean gutters.

Next, check the downspouts. Is water flowing freely out the bottom opening? Where does that water go? The water should discharge a few feet away from the foundation wall and should have a clear unobstructed path that leads it well away from the house. If there is a problem with downspout discharge, there are simple-to-install downspout extender pipes available at most home center stores. Some people prefer to connect their downspout to underground pipes that carry water well away from the house. While aesthetically pleasing and sometimes necessary to avoid walkways, such systems can be hard to maintain. When they get clogged or broken, repairs can be quite an undertaking. Typically such systems are installed by gutter specialists or landscapers.

b.) Grading.Look around your yard. Are there sizable puddles forming? If so, you need to fill in low spots or dig out channels so the water can flow away. Standing water in the yard acts like a reservoir, making sure your basement stays wet until the reservoir is depleted. Check for small rivers that go near the house. Reroute these by adjusting the grade so that they flow well away from the house. Landscapers can help you with these efforts.

Check your patios, walks and driveways.They should slope away from the house. If they are improperly sloped (usually the result of settling over the years), the best solution is often replacement. Sometimes, a layer of mortar and brick or flagstone can be placed on top of an old slab, yielding a very attractive and properly sloped surface. Be aware that it is nearly impossible to ensure that the new layer will form a lasting bond to the old slab. Masonry companies can help you explore your options.

Joints between walks, patios, drives, and the house, if exposed to direct rain, must be sealed with an appropriate caulk. Your local home center will have a variety of sealants that should be effective in this easy do-it-yourself project. No caulking lasts forever, but with caulking there is a high correlation between price and quality, so get the best and create a seal that will last.

The garden beds and lawn around your foundation should slope gently away from the house. Such ground should never be flat or slope toward the house. Check that landscape timbers and other garden bed borders are not acting like dams and retaining water near the house.

c.) Window wells and stairwells. Window wells and stairwells can present problems.

Usually the best solution is to install covers. Clear plastic, dome-like covers are available at most home center stores to fit many common window well sizes. This is another easy do-it-yourself project. If you need help, you can get it from just about any of the tradespeople you contract with to deal with other parts of the project.

If you have a stairwell, consider having a permanent roof built that covers the entire stairwell and any paved area at the top of the well that slopes toward the well. Besides preventing flooding, the roof will help keep debris out of the drain and keep the steps clear of leaves and snow in the fall and winter. This project is best left to a skilled carpenter.

Make sure all your window wells and stairwells have raised lips around their edges to prevent water in the yard from flowing into the well during a downpour. Check to see whether the corrugated metal walls of your window wells need replacing. If you have the surrounding ground regraded, whoever does the regrading can replace the wells at the same time. If the wells are made of brick, a mason or a skilled handyman can add another row or two of bricks on top of the existing wall.

Sealing basement walls. While controlling surface water is always a good thing to do, it won’t, as mentioned above, always solve your wet basement problem. You’ll often have to back up those efforts with additional measures, including sealing your basement walls.

In theory, you can seal your basement walls on the inside or the outside. Sealing the exterior wall to a point below the ground surface can help, but generally only if you have moisture problems high up on interior walls or if there are cracks in the foundation. Trying to seal the wall on the inside is usually unproductive or even counterproductive. First, it is very hard to create an effective seal on the inside. Second, if you do create an effective seal, you may be trapping water inside the wall which may weaken the foundation over time.

The far better solution is to seal the entire outside of the wall. For most homes this means major excavation work. Such a project can be very disruptive and can wreak havoc with shrubs and other plantings near the house. However, it can be the most effective, enduring solution to a wet basement problem. While the costs for an exterior excavation and seal are high, the project entails additional opportunities to garner benefits. As part of the project, you can insulate the outside of your basement walls. Usually done with rigid foam board (such as Styrofoam), such insulation can yield significant energy savings.

Most people also opt to install a drain pipe at the base of the foundation to assure that the soil around the foundation remains well drained. The pipe collects water from the soil, discharging the flow at an opening located downhill from the house. If there is no suitable downhill location for the discharge, a sump pump is used to pump the water up to a safe discharge location. Typically, either landscapers or waterproofing specialists handle such

projects. While the work isn’t technically difficult, the details are important, so make sure that someone on the crew is experienced in such work.

For many people, the excavation project provides an ideal opportunity to renovate their landscaping. It’s a good time to replace overgrown “foundation plants” installed by the builder. If done well, and if the old landscaping was getting shabby, the improvement in appearance can have a large impact on the resale value of the house. Occasionally, the improved resale value alone can justify the entire project.

Installing drain systems. Perhaps the most common wet basement remedy is a drain and pump system. However, this solution addresses the symptoms of wet basements rather than the causes. As such, it is less than ideal. However, the primary goal of a dry basement can be achieved with some certainty, which explains the method’s popularity with both contractors and consumers. These systems are not inexpensive. Installing such systems is what most “waterproofing” companies do.

Keep in mind, though, if you install such a system but fail to remedy surface water problems, your expensive new system may soon be overwhelmed. In some homes, even after you’ve solved all the surface water problems, you will still have a large amount of water. This underground water can come from springs or from quite distant surface water sources.

The concept of a drain system is simple. Hidden channels are created around the bottoms of the walls inside the basement and crawl spaces. The hidden channels are often called (somewhat inaccurately) “French drains” and consist of a perforated pipe set into a bed of gravel. These drains capture any water and carry it to a cavity under the floor (about the size of a microwave oven), in which a sump pump is installed. A sump pump is simply a water pump with an on/off switch activated by a float. The float looks like the common floats found in flush toilets. Whenever the cavity starts to fill with water, the float rises with the water. When the water reaches a certain height, the float pushes a switch and the pump goes on. As the water is expelled through a pipe to the outdoors, the water level in the cavity drops until the float drops to the point where the pump turns off again.

A less expensive but more vulnerable system uses plastic channels caulked into place around the base of the walls. This system is not effective against water seeping up through the floor.

A Warning

Many waterproofing companies advertise a free and complete analysis of your wet basement problem. These evaluations are usually conducted by salespeople with minimal technical training, and often the only solution they sell is the drain and sump pump system. It is not a surprise, then, that they arrive at the conclusion that the drain and sump pump system is the best solution for you 99% of the time.

For unbiased and much more comprehensive advice, you can hire a home inspector or engineer that specializes in wet basement problems. These inspectors do a much more thorough job and look at all the things outlined in this guide. As experts in the field, with experience in both diagnosing the problem and designing the most cost-effective solution for you, they are often a worthwhile investment. However, they typically charge $150-$200 for their services. The choice is yours.

Another common problem with waterproofing companies, especially in the Washington area, is price gouging. Several well-established firms in this market are believed to conspire to fix prices. Allegedly, in some cases, two so-called competitors may in fact be two branches of the same operation. Waterproofing is the one home service field in this area where a significant chunk of the market is held by completely unscrupulous firms. Be careful. Don’t let the firm’s size fool you.


There are many factors involved in a wet basement problem that can be summed up in three central ideas. Reduce ground water. Seal the foundation, if possible. Provide a means of handling the water that makes it to your foundation.

With the help of this guide, you can get started on your own. For quick, sure results, a waterproofing company recommended by ServiceMagic is probably your best bet. For the best long term results, conduct your own analysis of contributing factors and available solutions. An inspector can be a big help – especially if choosing the right course is proving difficult. While $200 is a lot of money for advice, it’s a bargain compared to spending thousands on the wrong solution.

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