How to water proof a basement


Basements suffering from moisture do set the alarms bell ringing. In fact, they are not only threatening your building foundation but are also making you unable to utilize a pretty good space in your house. Although, we understand that it is such an annoying problem for your house, there is no need to worry over it. Why? Because there is actually more than one solution that will let you say “good-bye” to leaky basements and enjoy moisture-free ones. Read on to find out the useful info you need on how to waterproof a basement.

So, how to start?

Initially, to tackle the problem you must start off by revealing the root cause of the water in your basement. Is it from an internal source or an external one? And if the source is external is it, for example, due to heavy rains that collect near the building and then throw off to the basement or due to something else. All these question marks must be first answered to be able to find the correct solution. Below, a simple experiment to let you first know whether moisture comes from outside or inside. This is really an important step prior deciding how to waterproof a basement.

  1. Tape a piece of an aluminium foil on an internal wall in your basement.
  2. Leave it for 24 hours.
  3. Check then both sides of the foil: If there is moisture on the face close to the wall then the source of water is external. If the other face of the foil is damp, then moisture is internal.

I discovered that the source of humidity is internal, what to do next?

Add a dehumidifier

If this is your case, then you are quite lucky. The problem is not severe and the solution is pretty simple. There’s actually high humidity in the air inside your basement and the not real source of water attacking the basement. All you need is a de-humidifier inside your basement to lessen the level of humidity.

Insulate pipes

If the interior air of the basement is high in humidity, cold surfaces such as pipes , will cause humidity to condense on it which leads to water dripping in the basement. Insulating the pipes with foam insulation will help eliminate this problem.

If the source of humidity is external, what to do?

Ummm, the workaround here is not as simple as the above one. However, here you have more than one solution to go for. You can either waterproof your basement externally or internally.

How to waterproof a basement externally?

Although expensive, this is the best way to get long-lasting waterproof basements. Apparently, getting your basement walls sealed from the outside will ensure that no water is either getting into your basement or even trapped inside the walls and hence will protect the building foundation. Unfortunately, exterior waterproofing is not so simple to do because it requires excavating around the house in order to coat basement walls from the outside, and therefore it is mostly recommended for a house that is still under construction. Anyways, if your situation is suitable for doing exterior waterproofing and you decided to go for it, here is how it should be done.

Plug holes and cracks in the foundation. Holes and cracks can make water leak into your basement. Plugging these holes and cracks will not definitely solve the problem completely but will help along with other solutions. Hydraulic cement works well for plugging these holes. You can get this job done by yourself. Use tools such as cold chisel , an angle grinder fitted with a masonry-cutting disc or diamond blade to apply the cement.

Coating the walls with a waterproof material. Many waterproofing paints, such as Thoroseal Super and  Febtank Super, are available in the market and are suitable for coating concrete or masonry. As mentioned before in order to coat basement walls from the outside, soil surrounding the basement should be dug to foot depth down. This is actually the main reason that makes exterior waterproofing more or less a bit complicated. Generally, some paints can be applied by rolling or brushing and others are applied by spraying, so decide which is the more convenient way for you before buying the paint. Reading the manufacture’s instructions is vital to ensure coating is done the right way. Nowadays, polymer based waterproofing materials are hitting the market. In fact, they offer better durability, easiness in application and are even more environmentally-friendly.

Divert water away from your foundation. In fact, just coating the walls with a waterproofing paint is not the solution but it is rather a part of it. To solve the problem effectively, then the source of leaking water and the basement should be set apart. There is more than one approach for doing this. 1- Forming a slope by the building to make any water that collects around the foundation to slide away from it. This is done by digging in the soil or adding extra soil to form the slope. 2-If the source of water is rain water then consider adding gutters to catch the rain and divert it at least 6 feet away from the house. 3-Installing a drainage system is another workaround. The idea of the drainage system is to direct basement water via channels to the sump pump which then pumps this unwanted water away from the foundation, keeping then the basement water-free.

How to waterproof a basement internally?

If compared to the exterior one, this solution is easier, cheaper and requires much less mess.  Interior waterproofing is ideal for buildings that are already finished and not under construction anymore. In addition, interior waterproofing in most cases is a do-it-yourself job with no need for a pro. Below, some of the solutions that can take place to waterproof a basement from the inside.

Coating interior walls. The approach here is almost similar to coating exterior walls but walls from the inside are coated instead of external ones. In fact, some paints such as the ones mentioned above (Thoroseal Super and  Febtank Super) work for interior walls in addition to external ones. But in terms of durability, coating interior walls is not a permanent solution. Why? Because if there’s a source of water from the outside it will keep on affecting the walls and the foundation, and the waterproof paint will just prevent signs of moisture from showing from inside the basement for some while. But since water is trapped inside the walls, at some point paint will peel due to this moisture. And hence coating the walls from the inside is not a solution, it just hides the problem for some while.

Plastic sheets. Instead of coating the interior walls, plastic solid sheets are applied to prevent moisture from entering the interior living space. Unlike the waterproof coats, this solution is more reliable in bridging  large cracks or any imperfections in the walls. Plastic sheets can even be utilized over already coated walls.

Installing a drainage system. Along with one of the above approaches, a good internal basement waterproofing could be achieved. Internal drainage system channels are installed under the basement floor; water flows in these channels and then pumped away by a sump pump. If looking forward for cutting down the costs, then consider implementing the drainage system by yourself. Breaking the floor tiles, burying the tubes and then re-covering the floors with tiles is a lot of hard work but on the other side will save you lots of money. As a matter of fact, a standard-sized basement could cost you on average between $3,000 to $8,000 if professionally installed drainage system. While a one installed by you could cost only $1,000.

Don’t forget to test your system when it is finished.

It is quite important to test the system to ensure it is doing the purpose correctly. For example, if you have drainage system or gutters implemented then inspect it whenever there is a heavy rain and make sure water flows the right way away from your foundation. Similarly, in case of a sump pump make sure the pumping is working correctly and no leakage or anything in the channels than can even get things worse instead of fixing the problem!

What’s the bottom line?

If your basement is suffering from humidity, then the earlier you take an action to cure it the better it is for your basement and for your house foundation. Leaving the leaking basement uncured will just keep the foundation getting weaker and hence the problem getting worse. If you don’t have a leaking basement but your house is still under-construction, then it is needless to mention how crucial it is to ensure that your basement is being waterproofed correctly from the very beginning. The ideal case is to get the basement waterproofed during construction to do the digging and burying of drainage system easily and correctly. Remember it is much wiser to avoid the problem rather than getting stuck with it then looking around for solutions to save you.