What to do if your basement floods and how to prevent it

How to keep your basement from flooding, and what to do if it does.

In our area (Northeastern Illinois) there have been some heavy rains, recently. In fact, 2008 had the most rainfall of any recorded year. I have been flooded (no pun intended) with phone calls from many former clients, as well as other people, looking for some advice on how to handle their wet basement problems. Here are some tips you can use to help keep your basement from getting wet in the first place, and some advice on what to do if you do get flooded.

As always, feel free to call us, at no cost, if you need further information of referrals.

To avoid basement water, here are some easy solutions:

First, some definitions:

A flooding basement is when there is standing water in the basement to a level of 6" or more. Basement flooding usually occurs when there is general flooding, like when a nearby river overflows its banks and there is standing water on the ground outside the house. The only way to avoid flooding is to raise the entire grade level of the house, which is not usually possible. If you live in a flood plain, it is highly recommended that you get a house on higher ground. There is no real solution to flooding. The house was simply built in a place where it should not have been.

Most times, basements do not flood, but have seepage. Seepage is when your basement floor gets some rivulets of water, when the carpet in the finished portion of a basement gets wet or when floor drains or basement sink drains back flow because of the large amount of water in the storm sewers. Basement seepage is easily avoidable, and easily cleaned up when it does happen.

Make sure that your roof's downspouts are in good condition and that the drain at least 6' away from the house (12' is better) and that they drain down slope from the house. The grade around your house should, ideally, slope away from the house at a rate of 1" down for each 12" away. This is a quick, easy and inexpensive solution. If rain water is drained away from the house, it will not come back into the basement. Added downspout sections cost as little as $4.95 for a 10' section. Avoid the cheap plastic add-on extensions and buy the metal ones, they last longer. A very simple, but the most overlooked solution, in my experience.

Make sure that you have a good quality de-humidifier in your basement (65 pints per day capacity, or better) and run it 24/7 from May through October. Buy a model that has an optional drain hose option. This will allow the water to drain directly into a floor drain and save you the grief of having to empty the de-humidifier when it gets full. Even if you don't have seepage problems, you still have high moisture and humidity levels in your basement (finished or not). A basement is underground, it is just a big hole and it will always be moist. Your house's foundation and basement slab are cooler than the rest of the house. They are underground and the ground is cold. During the summer, when there are high humidity levels, this humidity will condense on the foundation walls and slab and produce moisture. Use of a dehumidifier will also keep down your air conditioning bill. Dryer air feels cooler than humid air.

If you are experiencing water back flowing into basement floor or sink drains, hire a plumber to install a check valve in your main drain sewer pipe. A check valve will allow water to flow only one way, from your house to the sewer and not from the sewer into your basement. If the storm sewers fill, the check valve will stop the water from backing up into your basement. Another, less expensive solution is to have a stand pipe, which only has to be about a foot to a foot and a half tall, installed at the drain grate. If you use a stand pipe, you have to remember to insert it whenever it storms. In the Chicago area, basement's rarely "flood" (i.e., water coming into the basement from the exterior) but get flooded by water because the basement floor drains back-up from the sewers.

If you have a full or partially finished basement with carpet on the floor, make sure that you have a 6 mil plastic vapor barrier between the carpet pad and the concrete slab floor. When you think about it, a carpet pad is just a big sponge. This sponge will soak up any condensing (or seeping) water and wick the moisture right up to your carpet. Eventually, mold will form and you will have to replace the carpets. Install the plastic directly on the concrete slab floor. Overlap the seams of the plastic sheeting at least 6" and tape them with waterproof tape (NOT duct tape). Bring the edges up the walls, at least 2", and install the baseboard over the plastic. Also, make sure that basement carpets are made of synthetic materials, like polypropylene. These materials are much less prone to mold and, if dried quickly (within a couple of days) can be re-installed. There are even some newer products that allow a small air space between the slab and the floor, which will still keep the carpet dry but will also allow for any condensation to be air dried (See here: www.dricore.com ).

Make sure that all the drywall walls in your basement are properly installed. The bottom of the drywall should be installed at least a 1"" space above the concrete floor. This gap will keep water from wicking up the drywall and will help to keep it dry. If your drywall was not installed correctly, it is usually easy to just cut out 1' at the bottom. Most new finished basements are constructed with fiberglass faced drywall at the run closest to the floor. Fiberglass faced drywall will not support mold growth like standard paper faced drywall will. The face paper on normal drywall is very good mold food. This is true for normal drywall and for the so-called "water resistant" greenboard.

Make sure that your sump pump, and if you already have one, make sure that it is equipped with a battery backup power supply (NOT a cheap, 12 volt battery powered back-up pump. A regular 120 volt uninteruppted power supply). Many of our past clients have ignored the recommendation to install a battery backup. Their basements got wet. Power failures usually occur along with rain storms and the time you most need your sump pump is when it is raining. In addition, there are special back-up pumps that can be installed beside the regular pump. These back-up pumps will provide extra drainage flow if there is a large amount of water draining into the sump or in the case your main sump pump fails. When buying a sump pump, do not get a cheap model from your local Home Improvement store. Go to a reputable plumbing supply dealer and buy a heavy duty, commercial grade pump. They last much longer and have greater pumping capacity and are well worth their higher price. Make sure your sump pump is equipped with a check valve (allows water to flow out, but not back in) and make sure to change the check valve every 5 years because they wear out.

Before you finish your basement, make sure that all of the small, vertical cracks in the foundation wall have been properly sealed. It is not a good idea to purchase a new house with the basement already finished. As new houses settle (which ALL houses do) they will develop a few small cracks in the concrete foundation. This is normal and to be expected. These cracks are best fixed by a professional foundation contractor and using high pressure polyurethane foam injection. I have never seen such a repair fail and most contractors give 50 year warranties. Once the house has finished settling and these cracks are sealed, the basement can be finished. Just make sure that the contractor who finishes the basement properly insulates the walls (spray foam, Icynene is the best) and installs the required fire stops. Remember, cheap contractors do cheap work, which is very much more expensive, in the long run.

If you have basement water:

ASAP, make sure that there are no electric wires that are under the water level. Also, make sure that you are extra careful with electric devices in wet basements. If you have standing water (flooding) in your basement, disconnect the main electrical switch or call your local fire department to do it for you! Only, use ONLY double insulated and grounded vacuums and dehumidifiers. If you are in doubt about the electrical safety of your basement, stay out of it! You can live through the water damage but not through being electrocuted.

As soon as possible, suck up the water with a Shop-Vac and get some extra de-humidifiers running. Your air conditioner should also be running (it also de-humidifies). Keep the windows closed. The idea is to get the air in the house, and especially in the basement, as desert dry as possible as quickly as possible. This dry air will draw moisture out of the walls, carpet and other areas.

Take off the basement wall baseboards and drill 1" holes halfway between the wall studs at the base of the walls, about 2" off the floor. When you re-install the baseboards, they will cover these holes. The holes will allow moist air from behind the drywall or paneling to be dried as the de-humidifiers suck out the humidity.

Usually, if you get the basement dry in 3 to 4 days, there will be little damage and minimal mold formation. Even if mold does start to form, as soon as you dry out the basement the mold will stop growing (mold requires moisture to grow). It is usually necessary to rip out drywall and wood ONLY if there is a large mount of mold. Most times, there will only be a little mold growth and this will be behind the walls. If you keep the basement dry, the mold will not grow. Mold can be a problem to those with sensitivity or allergies, but mold only affects people because of the spores it puts out. If the mold is dead and not growing, it isn't putting out any spores. Most types of mold are harmless.

If you do get mold growth, do not use bleach to clean or kill it. The EPA has determined that bleach is NOT an effective fungicide and bleach puts out harmful fumes when used in large quantities. There are much more effective (and less harmful to humans and pets!) fungicides available at the major home stores. Spray them directly on the affected areas and let them kill the mold. These products will soak into the wood and drywall get to the roots of the mold, killing it completely. When the wood in the walls is completely dry, cover it with a mold encapsulating paint. This will cover the mold and keep it from growing further.

When all is dry (keep the basement windows closed and run the de-humidifiers, usually, for about a week or two to ensure complete dryness), it helps for your to call a licensed and certified home inspector who is also specifically trained and certified to perform mold testing. If you can hire an inspector who is also specially trained in thermal imaging, that will help to verify that the basement is fully dry. Ask the inspector for a mold clearance test, which is an air sample that ensures that mold spores are not present in the air. Make sure that the inspector does not do mold remediation, and that any mold remediation company you hire does not do the testing. This is a conflict of interest. If there are mold spores present, call a professional, licensed and certified mold remediation company. When they are done cleaning up, have the area re-tested by an independent mold inspector.

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