How to Waterproof Your Basement ( Suffolk and Nassau Residents)

Learn about the best way to detect a basement water problem, basement waterproofing, and get advice on the most effective way to solve it to avoid further damage to your property.

A lot of homeowners know very well that getting their basement flooded is one of the worst things they’ll ever want to deal with. Based on information from the ASHI, more than 50% of US homeowners have this issue. Some of the most common causes include groundwater swelling, runoff, and condensation. In terms of solutions, these depend on the cause of the problem and may range from installing a perimeter drain system to using a dehumidifier. If the last time you went down in your basement you noticed a musty odor and dampness, then these may very well be the first signs of the problem. At this point it’s vital that you take action right away and combat the water before it further damages your basement.


  • Get in touch with your local municipality to learn more about any potential changes in the water table. You can find a list of contractors and advice by contacting the NAWC at
  • Don’t try to combat groundwater swelling on your own. Instead, seek the help of professionals.
  • Try to get to the bottom of what caused the humidity in your basement prior to making any changes to your property.
  • Persistent musty smells should never be ignored.

(Basement) Condensation:

When warm, moist air hits cool foundation wells, that’s when condensation occurs. If you notice wets spots on your basement walls or floors, then you may be dealing with a condensation issue. To check it, you need to get some plastic wrap and tape it onto a damp spot. Make sure that the edges are sealed with tape for a couple of days. If the walls side of the plastic has moisture, then it’s a leak and you need to call a basement waterproofing professional to help waterproof your basement. If you see moisture on the exterior, then you have a condensation problem. If possible, try to keep a window open. In some cases, you may also want to use a dehumidifier as a long term solution.


Rainwater and melted snow are the 2 most common causes of runoff. Hydro-static pressure forces the water through cracks and gaps in the footings and walls. To prevent this, you need to ensure the ground outside your property slopes away from it at least 1” or twenty five millimeters vertically for every 12” or three hundred millimeters of horizontal travel. Furthermore, you also need to make sure that downspouts don’t pool or leak in proximity of the foundation.

(Basement) Groundwater Swelling:

When the water table exceeds its high point, groundwater swells. Since the soil that surrounds your property cannot hold the extra water, it causes a runoff issue. If this is what’s been causing your basement to become wet, then this means that after each storm your basement stays humid for a very long time.

Combating a Wet Basement:

Regardless if you use your basement as a storage room or whether it’s finished, your property’s structural integrity depends on having a healthy basement. As such, effective basement waterproofing is vital to making this possible. To prevent having a wet basement, you should first of all find out the type of problem you have. Secondly, verify the grading around the property, whether you have cracks in the driveway and don’t forget about checking the downspouts of potential pooling or leaks. Any problem you find should be fixed right away.

Using a Concrete Sealer:

If you want to coat basement floors and walls, you can easily use a concrete sealer. Not only are they simple to find and use, but they also offer a fast basement waterproofing solution. If you want, you can also decorate them. If you want, you can also apply them to damp surfaces. However, before you do that, make sure that standing water is removed.

Fitting a Polyethylene Membrane:

If you’re not the type to use an epoxy coating, then you don’t have to. That’s because you can also use a polyethylene membrane. Even though it manages to hold water effectively, you may have to install a sump pump and a channel to effectively collect and then remove water from the membrane (particularly, from behind the membrane). Whether this is needed in your particular case or not is up to the professional to say. Make sure to carefully measure the area you want to cover and check to see if you have enough membrane to cover it.