Waterproofing Basement Walls – Sealing And Fixing Damp Units

How do you waterproof a basement wall? In this guide, we will be discussing all you need to know about sealing your basement walls.

As useful as basements are, they require extra attention simply because of where they are located – below the ground.

But why is this a problem?

It is common knowledge that water flows to the steepest ends of any surface, so for the fact, your basement is located down below, it will always attract water.

Unfortunately, your basement walls will leak if it isn’t waterproofed.

That being said, we’ll be discussing damp basement walls, and how you can waterproof them effectively.

Waterproofing Basement Walls From Inside

When water invades your basement, it likely does so through the spaces in your basement walls. These spaces could be the pores in your poured concrete or cracks in the walls.

Either way, they are excellent passages for water to creep in and do some serious damage to your structure and property.

For this reason, sealing cinder block basement walls and other wall types should be taken seriously.

Thankfully, it isn’t a hard task to accomplish, and you can do it all by yourself, e.g, by paneling.

Here is all about basement wall waterproof panels.

Why Is My Basement Wall Damp?

I already mentioned that water flows to the steepest points of any surface, and since your basement is at the low end, water will naturally flow in that direction.

Before you begin to take steps to waterproof your basement, you need to understand why it keeps getting damp in the first place.

With this in mind, let’s take a look at some of the major reasons your basement walls are damp.

Porosity: Poured concrete walls are solid, and they can last for a very long time. But as strong as they are, they are filled with tiny pores.

These pores aren’t visible to the human eye because of their small sizes, but they are large enough to allow water to seep through.

Cracks in the foundation: When there is heavy rainfall, water can gather around the edges of your foundation. If it has a few cracks, then water can seep through and flow down your basement walls.

Poor drainage: If you don’t have proper drainage, then water can gather around your basement walls. The problem is, the water won’t remain there, as it will make its way through any leaks.

But with proper drainage, water will be channeled away from the foundation and will not be able to flow down to your basement walls.

Leaking pipes: If the pipes above your basement, either from your kitchen or bathroom are leaking, then the water can make its way through your basement ceiling and flow down your basement walls.

The Problem With Damp Basement Walls

If you think your damp basement wall isn’t a problem, then think again, as I will be listing the problems it can cause you at home.

It promotes mold growth: Mold spores exist in pretty much any space you can think of, and they are all around your basement. However, they won’t land and begin to grow on any surface if that surface is not damp.

If your basement walls are damp, then it will be a perfect environment for mold spores to land and begin to grow their colonies.

Besides making your basement walls look terrible, mold is also a health hazard, as it can cause allergies and infect human lungs – causing breathing problems along the way.

It weakens the structure: Leaving your basement walls damp for extended periods will cause them to weaken and develop cracks. It can also cause it to cave in, and that is terrible for the integrity of your structure as a whole.

It reduces the market value of your home: If you are planning to sell your home, then you can rest assured that damp basement walls will not do your asking price any good.

Potential home buyers will carry out inspections before they decide on whether they will buy your house or not. And if it is discovered that your basement walls are damp, they will underprice your home.

This is because the new owner will have to take on the responsibility of fixing the leaks and restoring the walls to their solid-state.

Why You Should Seal Your Basement Walls

The answer to this question seems pretty straightforward, however, it goes deeper than preventing water from penetrating the walls.

That’s indeed the main purpose of sealing the walls, but here are some of the consequences you will have to face if your basement walls aren’t properly sealed.

Damage to your structure: When water keeps seeping through the foundation walls and into your basement, the wall will begin to weaken over time.

Since the wall sits right by the foundation, being weak may spell doom for the rest of the home, as there is an increased chance of a collapse.

Devaluation of your property: A basement wall that has suffered significant water damage over time will not impress potential buyers when they come to inspect your house.

The prospect may lose interest altogether. Even if they still express interest in buying, it would be at a price that is way below your original asking price.

The reason for this is obvious – The new owner will have to pay for the fixes after the home purchase has been completed.

Mold and efflorescence growth: Besides compromising the strength of your structure, leaking basement walls also means mold growth.

As you may already know, mold thrives on wet surfaces, especially when these surfaces are in dark, warm areas. Your basement is one of such environments, and a leaking basement wall will be ideal for mold spores to land and grow.

Mold is known to cause allergies to humans when they make contact with it. To add to that, people with asthma and other respiratory problems can have their conditions worsened if they come in contact with mold.

Efflorescence can also begin to appear when your walls leak. Just like mold, it too thrives on damp surfaces.

Although it isn’t harmful to human health, it reduces the aesthetic appeal of your basement.

How To Waterproof Basement Walls

Now that you know why your basement walls are damp and the problems they can cause you, let’s take a look at what you can do to waterproof.

There are several approaches you can employ to do this, the first of which is hiring a professional waterproofer. They are experienced in the craft of basement waterproofing, and they will advise you on the right steps to take.

Waterproofing basement walls can be done on two fronts – The interior walls and the exterior walls.

Exterior waterproofing entails blocking off water seepage from inside the basement, while exterior waterproofing entails blocking off water from outside.

Here’s what you can do.

  1. Inspect the area

The first thing a professional waterproofer will do is inspect the foundation of your home and around the basement.

Their mission at this stage is to find out exactly where the water is coming from, and they can trace this by careful observation of watermarks on the wall.

They will also take a look at any pipes above your basement ceiling to trace leaks. Leaking pipes could be from your bathroom, kitchen, HVAC system, or laundry room.

After the water sources have been discovered, steps can be taken to stop the leakages.

  1. Seal the cracks in the foundation

If cracks are discovered in your foundation during the inspection, then it should be sealed immediately to prevent more water from seeping through.

Thankfully, there are many brands of concrete sealers you can use to do this, and a professional contractor can advise you on which is best for you.

Luckily, sealing external cracks isn’t such a daunting task so you can do it yourself if you haven’t hired a contractor.

Just visit a home maintenance store around your area and buy the right concrete sealer to patch up the cracks.

Read the instructions on the package carefully before you begin to ensure you seal the foundation cracks the right way

  1. Fix leaking pipes

Leaking pipes can be hard to deal with, especially if they have been installed within walls. Tracing the exact spot where a pipe leak is something best done by a contractor, but you can give it a shot if you have some experience.

Once the leakage is spotted, you will need to either buy a replacement pipe and install, or block the holes in the leaking pipe. But if the leakages occur in multiple areas of the piping, then you may need to replace them all.

I suggest you buy plastic pipes as replacements since they do not rust. Metal pipes can rust and begin to develop leakages again in the future.

  1. Install downspouts and gutters

Installing downspouts should be a major part of your exterior waterproofing plans. This is because the bulk of the water that dampens your basement walls come from outside.

If you don’t have a downspout system, or the one you have is too close to your building, then rainwater or melted snow will flow from the roof down to your foundation.

The case could also be that the gutters on your roof have been clogged by bird nests and water cannot be discharged properly.

If this is the case, then you need to unclog your downspouts by removing bird nests, twigs, leaves, and any other debris that may hinder free flow.

Another great idea is to add downspout extensions that stretch at least 30 yards away from your foundation. By doing so, any water flowing down from your roof will be discharged far away and will not rest on your foundation walls.

As long as the water is deposited far away from your foundation, then the chances of water seeping through to your basement walls will be reduced.

  1. Redo the landscape

Some landscapers make the mistake of tilting the yard towards the direction of your home. This means anytime there is heavy snow or rainfall, water will flow towards your home and rest on your foundation walls.

If your landscape is of this nature, then you need to redo it to keep water from resting on your foundation walls. This is a time-consuming process that will cost you some money (and maybe some inconvenience), but once it’s done, rainwater will be able to flow away from your foundation, and not towards it.

Hence reducing the chances of water seepage through your basement walls.

  1. Apply waterproofing paint sealers

Once you’re done waterproofing the exterior foundation, you can begin to work inside.

Since poured concrete walls are porous, it means water can seep through the pores. But you can stop this from happening by applying paint sealers.

These have thicker coats than regular paint, and they can penetrate the concrete pores and dry inside, thereby blocking the spaces that water can pass through.

Before you apply the waterproofing paint, make sure your basement walls are free of mold and efflorescence, as these will not allow the paint to properly adhere to the walls or penetrate deep.

All you need to apply waterproofing paint is a paintbrush or roller. The application process is the same with regular paint. You can apply an extra layer of the coating after the first one is dried up for best results.

How To Seal Basement Walls

Now that you understand why it is important to seal your basement walls, let’s take a look at how you can do it all by yourself!

Step one: Remove the water before you begin sealing

In a case where the leaks in your basement wall have caused flooding, it is advised that you first remove the water before you begin sealing.

This is the best thing you can do, as standing water may make it hard to locate the source of the leak. That aside, standing water is dangerous if the electricity is on.

Cut off the power in the basement, then go in and remove the standing water before you take the next step.

Step two: Find the source of water

You can’t begin sealing your basement walls without first identifying the leak. This could either be one or more cracks in the wall itself or by the cove joints.

Careful observation is all you need to spot the source. Move away from any furniture by the leaking wall so you can have a better view.

Check for water drip marks and use them to trace the cracks. The drip marks typically start from where the cracks are.

Once you have identified the cracks, you can move on to the next step.

Step three: Prepare the surface

Obstacles will not allow you to seal your basement walls properly so you should get rid of them first.

Remove any furniture that blocks the wall cracks so you can have more workspace. You should also use a brush to clean off any debris that’s stuck in-between the cracks.

Some quick swipes will remove chips, dust, and spider webs, and this will create a better surface for the cement to adhere to.

Step four: Seal the cracks with hydraulic cement

Hydraulic cement is great at fixing both interior and exterior cracks in your basement walls. They come in a powdery form but quickly turn into a putty-like substance when mixed with water to form a trustworthy sealant.

To use hydraulic cement, mix a portion of the material with some water (as recommended by the manufacturer), then use a spade to scoop up a desired amount of the mixture and paste it deep into the cracks.

The good thing about hydraulic cement is that it expands in the spaces, so it makes them water-tight.

You can apply another layer of the mixture if the first one was insufficient. Be sure to level the plaster with the wall’s surface, just so the patch blends in with the rest of the wall.

Step five: Apply to finish

Now that you are done sealing the wall cracks with hydraulic cement, it would be nice if you gave it a smooth finish, just so your basement will maintain its beauty.

While using regular paint is a good idea, waterproofing paint is much better.

The good news is, the latter also comes in several colors to match the already-existing color of your basement walls. Not to mention the fact that it is thicker than regular paint and it stops seeping water from making it to the inner surface of your basement wall.

If you’ve never used waterproof paint, then keep reading, as I’ll be discussing it next!

Applying Waterproofing Paint

Cracks in walls aren’t the only cause of wet basements. As hard as concrete walls are, they are also very porous.

Indeed, you can’t see the pores, but these microscopic passageways are present, and they provide the spaces for tiny droplets of water to seep onto the interior wall surface.

To be sure water is seeping through the pores in your basement walls, you can do a simple foil test. This will involve taping a piece of foil paper on your basement wall and leaving it there for a few days.

Take off the foil and inspect the part that rested on the wall to see if it has collected any moisture. You will find droplets on it if it has.

Going by the results of the foil test, it would be wise to waterproof the inner parts of the wall, and waterproof paint is ideal for this job.

There are different makers of waterproof paint, but the rules of application are pretty much the same.

Here’s what you need to do to seal your basement walls with waterproof paint.

Step one: Clear the surface

Remember, waterproof paint is meant to sink into the pores of your concrete basement walls and solidify within, making it impossible for water to pass through and settle on the surface.

But this will be impossible if there are other forms of matter on the walls, as the waterproof paint will be unable to pass through the blockages.

Therefore, you must first clean the surface of the walls before applying the waterproofing paint.

Remove any mold growth or efflorescence build-up and scrape off the old paint so that the concrete wall and its pores will be fully exposed.

Step two: Apply the paint

Now that the concrete wall is bare, you can begin applying the waterproof paint. You can use a paintbrush or a roller for this task.

For the first layer, dip the roller into the paint bucket and spread the content across the wall. Leave no area untouched as you paint, you can use the brush to paint over tight corners that the roller can’t access.

You can stop painting when you’re sure you’ve covered the entire wall.

Step three: Leave the paint to dry, apply another coating if need be

Leave the first layer of waterproof paint for a few hours to dry, then take a look at the wall to see how much of the paint sunk into it. If the surface paint looks faded, then you can apply another coating over it for reinforcement.

Be sure to spread the second coating evenly across the wall so you’d have a beautiful finish. Remember to use the roller to paint over the wider spaces, and the brush to paint over the hard-to-reach areas.


Sealing your basement walls from the interior and exterior is something you can do all by yourself. Just follow the tips provided in this article.

However, if you’re not up for it or simply don’t have the time, then you can call a local contractor to get the job done. Although this is the more expensive option.

Waterproofing your basement walls will keep them free of dampness, which will in turn prevent efflorescence and mold growth.

You should hire a professional service to inspect for the source of dampness before you begin.

Thanks for reading!

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