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

By William Decker, CMI, Decker Inspection Services

 

In our area (Northeastern Illinois) there have been some heavy rains, recently.  In fact, 2008 had the most rainfall of any recorded year and this year (2014) has been very cool and wet one.  I have been flooded (no pun intended) with phone calls from many former clients, as well as people I have never met, 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 or obligation, if you need further information or referrals.

To avoid basement water, here are some easy solutions:

 

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First, some definitions:

 
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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 above the house foundation grade outside the house.  Flooding HouseThe only way to avoid flooding is to raise the entire grade level of the house, which is not usually possible.  If the ground around your house is higher, it may be possible to dig out a swale to help drain the water away from your house.  If you live in a flood plain, it is highly recommended that you get a house on higher ground.  There is no real 100% foolproof solution to flooding.  The house was simply built in a place where it should not have been and the municipality you live in does not provide adequate drainage and flood prevention measures.

 

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Under the ground, water exists at some level.  This is called the "water table".  The water table is the level at which free standing water exists.What is the water table?  When one digs a well, they are drawing water from the water table.  The level of the water may vary depending upon area, whether conditions and regional rainfall differences.  People building houses with basements that extend underground and in some areas the water table level can greatly vary.  If it rains significantly, raising the water table, this rising water will enter the basement and flood it.

 

But even worse than the damage caused by basement flooding, the rising water table will also shift the soil and the house's foundation wall footings will shift.  This can cause significant structural movement of the house's foundation and can even, in extreme cases, cause structural collapse.  Most people believe that a drain tile and sump pump system is supposed to guard against basement flooding (and it does, to a certain extent) but the main reason for a sump system is to guard against rising water table water ruining the structure of the house.

 
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Most times, basements do not flood, but have minor seepage.  Seepage is when your basement floor gets some little rivulets and puddles of water, usually no deeper than 1/4 to 1/2" deep, which soaks and ruins the carpet in the finished portion of a basement.  Seepage usually occurs when there are cracks in your basement's concrete foundation walls or, if you have an old house, when the brick, CMU or stone foundation leaks.

 
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As a property inspector, I have seen many houses and have also seen the trends in residential construction change.  New housing developments, and even one property tear-down new construction, is trending towards larger houses.  Where I live, the houses were mostly small ranch houses that were built on large lots.  The building boom of 2004-2008 saw many of these smaller houses torn down and larger houses built on the larger lots.  But larger houses have more people and use more water.  The original house may have had 1 or 2 bathrooms, but the new house will have 3 - 4 bathrooms and maybe a few additional powder rooms.  Add to this the larger kitchen and, many times, 2 different laundry rooms.  The same property is now using and disposing of 2 to 3 times the water that it originally used.  This is OK, but the village did not also increase the size and capacity of the sewer system.  The "brown water" sewer system has to handle more waste water, as does the local water treatment plant.  The rain water sewer system is also affected.  The larger house has a larger footprint and covers more of the lot's ground area.  With more house, there is less ground surface area and less area for water to naturally percolate into the soil.  Now the water is being shed by the roof and collected into the gutters and sent to downspouts which, more often then not, empty into the undersized sewer system.  These sewer systems can no longer take all this water away and it backs up into the basement drains, which are at the lowest levels of the house.

 

Finally, know this truth.  You may not like it, but it is true.  There is no such thing as a basement that won't get water!  Some will flood and some will get minor seepage, but EVERY basement will get water.  No matter how well built or "water proofed" or how large a sump pump and / or flood control system you install, ALL basements will get wet.  Maybe not today or next week, but at some time in the house's life, it will get water.  So, the point is not to spend all your time and money trying to put off the inevitable, it is to be smart and arrange your basement so that when the water does come in, it will do little or no damage.  Don't put anything that you don't want to get wet in your basement.  When you store stuff down there, put it up on shelves or skids, NOT on the floor.  Don't finish the basement with expensive furniture and carpeting and, especially not, hardwood flooring (really!  Some people actually do this!).  Be smart.

 
 
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If you live in a large city, such as Chicago, the municipal storm and drain sewers can become overloaded with floor drains or basement sink drains backflowing because of the large amount of water in the storm sewers.  Chicago, being older, does not have separate rain water and brown water systems, but only one "unified" sewer system.  When these systems back up, the water is more than just "rain water", if you know what I  mean. This condition can be solved by a couple of methods:

 
 
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Flood control systemThe expensive, but permanent "fix and forget" method is to have a check valve installed between your house's drainage system and the municipal sewer system.  This is usually called a "flood control" system.  A cistern is dug in the yard and the house's sewer system is run through it. In normal times, the sewer water just runs through as before.  If the municipal sewer system fills up, no water is allowed to flow back to the house because it is stopped by one-way check valve which only allows the water to flow outwards.  Any water from the house that cannot run to the sewer when these valves are closed accumulates in the cistern and is later pumped out by an ejector pump. Installing a check valve will allow water from your house to drain into the sewer, but prevent any sewer water from backflowing into your house.  This solution works very well, but requires a plumber and some expensive digging to install.

 

 
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The inexpensive alternative, if there is only minor backflow, is to install a stand pipe in all the basement floor drains.  When I was young, this used to be a pretty involved installation issue, with breaking up basement floor concrete and leading floor drain pipes.  Nowadays, this is a relatively easy process.  You can purchase a flood drain stand pipe for under $15 that will fit into your floor drain and has an expanding rubber gasket to seal it tight.  Once installed in each basement floor drain, this gasket allows you to screw a threaded pipe into the gasket.  This pipe, usually about 1 1/2' long, stands above the floor level and any backflowing water rises up into the pipe and NOT onto your basement floor.  This utilizes an simple principle of physics.  The pressure of the water flowing back into your basement can be easily countered by the pressure of the water "standing" in the standpipe.  I know it sounds implausible, but it works.  Go figure.

 
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Also easily installable are floor drain check valves.  It looks and installs just like the stand pipe, but instead of a stand pipe, there is a flapper valve in the opening that acts like a check valve.  This valve allows water to flow into the drain, but closes up is water backs up from the drain.  It costs about $20.00.

 

 
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Sump pumps are commonly seen in houses, these days, but their function is largely misunderstood.  Most people thing that a drain tile and sump pump system will prevent water from entering their basement through the walls, during a heavy rain.  This is not true.  As mentioned above, under your house and depending upon where you live, is the water table.  This is the level at which is you dig down, you would hit water.  In the Chicagoland area, this is not very far because of our proximity to Lake Michigan and the many rivers in this area.  When it rains, the water table rises.  If the water table rises higher than the floor of your basement, water can seep in between the basement slab and the foundation wall.  In areas with high water tables, builders install a "drain tile" system around the house's foundation.  This is a system of perforated pipes They are called drain tiles because they used to be made out of clay) that run parallel to the bottom of the house's foundation and drain into a pit located in the basement floor (the sump).  Because the bottom of the sump pit is lower than the basement floor, water drains from the drain tiles into the sump.  Many times, the bottom of the sump pit is also perforated to allow water to drain into it, directly.  In the sump pit is a pump with a float switch.  When the water level in the sump pit rises, this switch turns on the pump.  This pumps the water out of the pit and into a pipe which ejects the drainage water out of the house and (hopefully) far away from the house.  Some common errors with sump pump system installation is to drain the water back into the sewer system (not allowed in most areas) or to have the sump drain right outside the house, where is just flows back into the drain tiles and can overload the system.  Another error is to only have one pump (no backup) or to have no secondary power supply for the pump, should the power fail.  These "backup-systems" should include a full sized, 120 volt secondary pump (not the cheap 12 volt "batter backup" systems) and be powered by a 120 volt power backup system, like a UPS (Uninterrupted Power Supply) or a backup generator system.

 

How to avoid flooding.

 

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Make sure that your roof's gutters and downspouts are in good condition, free of leaves and debris, that they drain at least 6' away from the house (12' is better) and that they drain down slope from the house.  They SHOULD NOT drain into the municipal sewer system, this would only increase the amount of water backflowing into your basement.  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.  If this water is percolated back into the soil, it will not backup into the sewer system.  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 and do not leak.  Downspout additions should also be secured with sheet metal screws and your landscaping company should be warned to not remove or physically damage them.  This is a very simple, but the most overlooked solution, in my experience.

 

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If you don't have room to extend the downspouts, underground PVC drain pipes can be installed and the rain water can be directed to the back or front yards.  These drainage pipes are equipped with "pop-up" drains at their ends, which pop up to allow the water to drain into the soil away from the house (just make sure that the don't wind up flooding out your neighbor's basement!).

 

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Make sure that you have a good quality de-humidifier in your basement (65 - 70 pints per day capacity, or better) and run it full power, 24/7 from April through October (Chicago area advice, it's humid here 3 seasons of the year).  Buy a model that has an optional drain hose option.  This will allow the water to drain directly into a floor drain or sink and save you the grief of having to empty the de-humidifier when it gets full.  (Just remember to clean the de-humidifier coils every month so that they do not become clogged with dust or pet hair.)  Even if you don't have seepage problems, ALL basements  still have high moisture and humidity levels (finished or not).  A basement is just a big hole in the ground and it will always be moist.  Your house's foundation and basement slab are cooler than the rest of the house.  It is 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.  It is also a good idea to run your furnace's blower fan, 24/7, during the summer to ensure proper air flow.

 

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If you have a full or partially finished basement with carpet or hardwood on the floor, make sure that you have a 10 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 or hardwood flooring.  Eventually mold will form or the wooden floorboards will buckle and you will have to replace the flooring.  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 ).

 

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Make sure that all the drywall walls in your basement are properly installed.  Drywall will wick water upwards into the walls. The bottom of the drywall should be installed with 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 wick moisture and does not support mold growth like standard paper faced drywall will.  The face paper on normal drywall is manufactured using re-cycled newspaper and is a very good mold food.  This is true for normal drywall as well as the so-called "water resistant" (NOT water proof!) green board.  Mold doesn't see the color of the drywall paper, but only sees a big, fat meal waiting.

 

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Make sure that your sump pump, and if you already have one, is equipped with a 120 volt UPS battery backup power supply. NOT a cheap, 12 volt battery powered back-up pump.  (A regular 120 volt uninterrupted power supply).  Many of our past clients have ignored the recommendation to install a 120 volt UPS backup and have suffered greatly for it.  Their basements got wet, their carpets were ruined and the drywall got all moldy.  Power failures usually occur along with rain storms and the time you most need your sump pump is when it is raining.  In addition, you should install a 2nd, full sized, 120 volt pump beside the main pump.  These back-up pumps are usually placed 6-8" higher (on a couple of bricks) than the main pump and 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, cast iron cased commercial grade pump.  They last much longer and have greater pumping capacity and are well worth their higher price.  Make sure each 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.  It is also a good idea to have your sump pipe drain outside and away from the house and not drain into the local sewer system (in some municipalities, draining the sump pipe into the sewer is illegal).

 

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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, vertical (within 30 degrees of vertical) cracks in the concrete foundation.  This is normal and to be expected.  These cracks are best fixed by a professional foundation contractor and using epoxy or 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 (usually in 2 - 3 years) and these cracks are sealed, the basement can be finished.  Just make sure that the contractor who finishes the basement properly insulates the walls and rim joist areas (closed cell 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 already have basement water.

 

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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 MUCH better than you can being electrocuted.

 
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The key to the next step is go get the basement dry, ASAP.  As soon as possible, suck up the water with a Wet-Dry vacuum and get some extra de-humidifiers running.  You can easily rent an industrial strength de-humidifier from a restoration company for $100 - 200 a week.  Your air conditioner should also be running in the "meat locker" temperature ranges (it also de-humidifies).  Add a few fans to keep the air circulating.  Keep the windows closed, the air outside is usually humid after a rainstorm.  The idea is to get all the air in the house, and especially in the basement, as desert dry as possible as quickly as possible.  This dry air not only evaporates the standing water but will also draw moisture out of the walls, carpet and other areas.  Remember that this takes time (usually, 1 - 2 weeks) so take your time and do it right.  If the basement is dried quickly, the likelihood of mold formation is lowered.

 
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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.

 
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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 start growing again.  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 there is visible mold growth, there is no reason to have it tested.  If you see mold, you already know it is there and you have no need to find out what kind of mold it is because the remediation will be the same.

 
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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 for mold growth on drywall and wood 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 (following the label directions) and let them interact with 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 seal up the mold and keep it from growing further.

 
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If you have extensive mold growth, DO NOT TRY TO GO ON THE CHEAP!  Hire a professional and certified mold remediation company to clean the mess up.  Sure, I know this can be expensive, but doing the cheap and easy thing is ALWAYS more expensive, in the long run.  Stay away from handymen or the proverbial "Two guys in a white van".  Mold remediation is a complex and technical trade, requiring a great deal of specialized training and certification.  If not done properly, the mold will come back, and much worse!  Do it right.  The EPA standards state that if the mold is plainly visible, there is no reason to have the mold tested, however, it is highly recommended that the affected areas be air sample tested one week after the remediation is done by an independent mold testing professional, NOT by the remediation contractor.  This testing will determine if the remediation work was properly completed.  Remember, test AFTER and have the testing professional be independent.

 
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Again, don't put anything you don't want to get wet in your basement.  Basements are holes in the ground into which water gathers.  Sure, you can minimize this water but you CANNOT stop all of it.  Put stuff up on shelves or skids or other things to keep it off the floor.  Water will actually work its way through the concrete slab (which, like all masonry, is porous) and form on the bottom of boxes and under your carpet or hardwood floors.  Don't believe me?  Thy this little experiment for yourself.  1) Get a 2' x 2' sheet of clear plastic.  2) Lay it on your concrete basement floor and take down the edges with duct tape.  Tape it tight.  3)  Come back in a couple of days.  You will see moisture has formed under the plastic.  Don't fall for the "basement water specialists" who "guarantee" that you will stay dry.  Ask for the guarantee, in writing, and actually read it before you pay.  Basements are nice and it is good to have a "man cave" or a recreation room, but a basement is still a baement.

 
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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 also do mold remediation work, 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.  For large or long sitting (you were flooded while away on vacation, for example) it is also wise to hire a licensed, certified and professional industrial hygienist to evaluate the problem and prepare a clean-up plan.  Most professional mold remediation companies have industrial hygienists on their staff.

 

Hope this helps;

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