Seal basement wall: Guide To Waterproofing Basement Walls

Guide To Waterproofing Basement Walls

Nobody likes a wet basement. You can do some waterproofing yourself, but if you’ve got a severe water problem, your best bet is to call in a pro.

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Because they’re below grade and close to the water table, basements tend to be damp. That can be a major issue for anyone hoping to finish their basement, because drywall, flooring and interior paint all perform poorly in damp conditions.

It’s a problem even for those who leave their basement unfinished. Dampness promotes the growth of unhealthy mold, and standing water can render parts of the basement unusable.

If you’ve got a basement moisture issue, you’re probably wondering about your best options. To answer some common questions, we spoke with Dallas Nevill, owner of Rainbow Restoration, a Neighborly company.

He confirmed you’ve got problems any time you see water in the basement, but wasn’t bullish about DIYing a full-on waterproofing project. It’s a multistep procedure that may involve outdoor work to improve drainage around the foundation and/or installation of a sump pump. A pro can determine a better basement waterproofing strategy than most homeowners.

However, that doesn’t mean you shouldn’t consider doing some of the work yourself. If the problem isn’t severe, you may get by with something as simple as a waterproof coating on the walls. That’s basically a painting job, and most homeowners can do that.

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Signs You Need To Waterproof Basement Walls

It’s easy to figure out you have a problem if there’s water on the floor, but other indications are more subtle. Moisture can come from the inside as condensation, or outside as seepage or leaking. Here’s how to waterproof a basement floor.

Here are some things to look for:

  • Soft or discolored drywall on finished basement walls.
  • Excessive condensation on pipes and ducts.
  • Musty odors.
  • Cracks and efflorescence on concrete walls.
  • Noticeably damp and humid air.
  • Water tracks on wall around basement windows or rotted wood in window casings.

It’s important to distinguish between moisture coming from outside and condensation originating from inside the basement itself. Here’s an easy way to do this:

Tape a piece of aluminum foil to the wall, leave it for a few days, then check it. If the side facing the room is wet, that’s an indication of condensation. If the side facing the wall is wet, you’ve got a seepage problem.

When Is Waterproofing Basement Walls DIYable?

When condensation causes a damp basement, homeowners can often remedy the situation themselves. It may simply be a lack of ventilation, and running a fan or dehumidifier may be the solution.

If the laundry room is in the basement, the dryer could be generating humidity. You could possibly isolate it with new walls. Homeowners can also insulate water pipes and HVAC ducts where condensation forms.

Other measures include applying a waterproofing coating or reinforcing the seal around basement windows with spray foam insulation. Outdoor drainage issues can be corrected by adding downspout extensions to divert roof runoff away from the foundation.

Water actively seeping through the walls or collecting on the floor is more serious and is often better left to pros. It may call for a new foundation drainage system, installing drain tiles on the basement floor, or perhaps a sump pit and sump pump.

Water accumulation in window wells may call for better-fitting covers or even window renovation. If you need professional waterproofing, nevill says, expect to pay between $3.50 and $6.50 per square foot, with the average total cost between $1,900 and $6,000. Here are the basement waterproofing costs you can expect.

Prepare for Waterproofing Basement Walls

To get ready for waterproofing, Nevill recommends moving large obstructions out of the basement so that work can proceed smoothly.

It’s also important to remove standing water and dry things out as much as possible, particularly if you’re waterproofing the walls. Waterproofing coating products only adhere to dry surfaces.

DIY Methods for Waterproofing Basement Walls

There are basically two methods, depending on whether the moisture is coming from inside or outside.

Insulate the walls

Humid air in the basement can cause moisture to collect on the walls, which are colder than the rest of the room. In this case, adding wall insulation is usually the best approach.

You can frame new walls and fill them with batt insulation, which will cost, on average, between $1,000 to $1,600 for 300 square feet of wall space. If you add drywall, the cost is likely to run from $2,500 to $6,000.

If you don’t want to go to that much trouble and expense, you could adhere rigid foam insulation to the walls with construction adhesive. That will cost between $300 and $500 for 300 square feet.

Apply a waterproofing coating

If the walls are damp with seepage from outside but they aren’t actively leaking, an elastomeric waterproofing coating can seal them. You can apply most products yourself by brush, roller or spray.

Before you do, patch cracks with hydraulic cement and remove efflorescence. Scrape it off with a wire brush or dissolve it with a solution like muriatic acid. You also need to dry the walls, which may require a heater, fan or both.

A product like Drylock costs about $50 per gallon and covers 75 to 100 square feet. You usually need two or three coats for effective sealing, running the cost to cover 300 square feet to about $500.

How Long Does Basement Wall Waterproofing Last?

On average, at least 10 years, but it depends on the amount of hydrostatic pressure groundwater exerts on the wall from outside.

If your coating fails prematurely, you’ll probably need to install a drain, regrade around the foundation or, in severe cases, dig out the foundation and install a waterproof membrane. Hopefully the situation will never come to that. But if it does, it’s best to let a pro handle it.

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The Right & Wrong Way To Waterproof Your Basement Wall

Home > Blog > The Right & Wrong Way To Waterproof Your Basement Wall


If you want to know the right and wrong way to waterproof your basement wall, this is the article for you. There are many blogs out there promoting “waterproofing paint” or “concrete sealers.” These products may sound affordable or practical but be warned. They’re not.

What Happens If You Don’t Waterproof Your Basement Wall?

Without a waterproof basement wall, your foundation is susceptible to moisture intrusion. If you’ve ever noticed that your basement is damp, it’s probably because water is seeping through your concrete. Your basement might also have humidity problems because moisture is sitting on your floors or sticking to your walls. Here are a few things that can happen when water enters your basement.

  • Mold – Mold can be extremely unsightly and unhealthy. Once humidity levels reach around 70%, your basement becomes home to all types of mold, rot, and mildew. Rot can eat away at stored furniture and structural joists. Mold can cause breathing problems, eye irritations, and skin issues.
  • Odors – Mold growth and sitting water can release foul-smelling gases that permeate the room and stick to your carpet, clothing, and furniture. Because you breathe the air from the floor below you, these smells can travel up to the rest of your home and begin to affect your family.
  • Structural issues– Water seepage clearly indicates that excess moisture is building up in the soil directly outside your basement walls. If too much water saturates the soil, it can lead to hydrostatic pressure. This is when the pressure outside your basement becomes too much for your concrete walls to handle, causing them to bow, shear, tip, or lean.
  • Insects and rodents – A damp basement is the perfect breeding ground for all sorts of pests. Fruit flies will nest in puddles and wet corners of your basement. Rats and mice love damp and cluttered areas, leaving pheromones that will attract more rodents.

Overall, a basement without a proper waterproofing system leaves the space under your home vulnerable. Whether your basement is finished or not, always keep in mind the risks of leaving it unprotected. That brings us to our next point.

What’s The Wrong Way To Waterproof Your Basement Wall?

Stay away from “waterproofing paint” and “concrete sealers.” These coatings may be easy to apply, but if you read their warranties carefully, you’ll notice they’re not as effective as they sound. These products are usually oil or latex based, claiming they stop moisture penetration. They also claim they can withstand 8 to 12 pounds of pressure per square inch. For every four feet of water, nearly 300 pounds of pressure per square foot can push against your basement wall.

These coatings also claim they can stop mold growth. But, we at The Real Seal have seen mold growing on all sorts of waterproofing paint products. Overall, these coatings don’t penetrate the concrete deep enough to keep water from seeping through. In fact, these coatings just keep water from seeping out of your concrete, keeping the moisture inside your walls, leading to honeycombing and efflorescence. The total lifespan of waterproofing paint is around two years, making it a very temporary solution.

What’s The Right Way To Waterproof Your Basement Wall?

The best way to waterproof your basement wall is by installing a three-part system. This system comprises of a drain tile, vapor barrier, and sump pump.

  • The drain tile – A drain tile isn’t really a “tile.” It’s actually a series of perforated pipes laid in a bed of washed stone placed right at the base of your foundation walls. If placed inside your basement, they collect rising groundwater that’s trying to seep through your cove joints (the space where your wall meets your floor). If placed outside your walls, they collect water that’s seeping into your soil. Both placements work and accomplish the same task. But, they are only one part of a working system.
  • The vapor barrier – A vapor barrier is a thin polyethylene sheet (10 to 20 mil thick) applied to the inside of your basement walls. This sheet catches water that seeps through your concrete, channeling it downwards to the drain tile below. This prevents water from ruining your drywall or paneling. Note: In order to apply a vapor barrier to a finished basement, we will need to remove any finishes.
  • The sump pump – The sump pump is the final working part of the system and the critical component in removing the water from your basement. Once water is collected in the drain tile, it’s carried to a sump pit (a small well in your concrete floor). Inside the sump pit is the sump pump, a mechanical device that detects when water reaches a certain point in the pit. Once the water reaches a certain level, the pump turns on and begins to eject the water from the pit through discharge lines. These lines lead out of your basement and deposit the water away from your foundation.

All three parts of this system create the most effective waterproofing solution.

Who Can Waterproof Your Basement Wall?

If you live in the Chicagoland area and need professional solutions, call The Real Seal. We’ve been waterproofing basements and other foundation types since 2011. Our foundation waterproofing experts will inspect your basement, find out where water is coming from, why it’s building up outside your walls, and employ the best waterproofing system ever. We also offer foundation repair, concrete leveling, and more. Call today for your free inspection and estimate.






Austin Werner

Austin Werner is the Owner of The Real Seal LLC, a basement waterproofing and foundation repair company. Austin believes that having a highly trained and happy team is the key to success. This is reflected through hundreds of 5 star customer reviews his company has received online.




Basement waterproofing from the inside: materials and methods

Basement (colloquially cellar) – a technical room, partially or completely located below the ground surface. It houses various communications – water supply and sewerage, power electric cables, as well as devices and mechanisms for controlling them. Basements are traditionally used for storing rarely used items and canned food. Their flooding with ground or flood waters complicates the operation of the house and in some cases provokes the destruction of the main supporting structures of the structure. To prevent such incidents, the cellar is sealed from the inside.

Conditions under which basement waterproofing is possible

Protecting the basement from water from the inside is aimed at preventing flood waters from flooding it, which is seasonal and periodic. Therefore, most often it is made some time after the start of operation of the building. Because of what, the foundation tape and the base may already have damage and defects, which must be taken into account so as not to waste time and money.

The waterproofing layer is applied to the capital structures. Therefore, before starting work, you need to assess their condition. The following factors are taken into account:

A private house can be built without any project at all, and there is often no technical supervision of the progress of work. Therefore, after buying it, you should prepare to get acquainted with pleasant and unpleasant surprises. Traditionally, the foundation is cast from concrete in the form of a tape or laid out from blocks, after which a plinth of red or silicate bricks is arranged on it.

Perhaps this is the most optimal option for a waterproofing device. And then only if the basement has a concrete floor. The fact is that flood (horse) water does not exist separately from groundwater. Melting snow or heavy rains cause them to rise, which will necessarily entail its penetration into the basement from below, bypassing the enclosing structures.

In the absence of a solid waterproof floor in the cellar, you will have to create one, otherwise the waterproofing work does not make sense. Even if the basement walls are insulated. To do this, a concrete screed is poured over steel reinforcement, and this frame must be paired with the foundation tape.

More difficult is the case when the base is laid out practically from the level of the ground surface. Since brick has a much greater hygroscopicity than concrete, in this case it is already necessary to change the properties of the material, reducing the number of capillaries in it. The need to install a concrete base over the entire basement area remains an urgent task in this case, but it becomes more complicated because it needs to be deepened.

With other foundation designs, for example, if it is made columnar, waterproofing the foundation from the inside from groundwater can only be considered as an additional measure. The basis of protection should be reclamation work on the site. These include the laying of drainage lines and the installation of prefabricated wells.

Types of waterproofing and how to apply it

Cellar isolation from groundwater can be done in three ways:

  1. Coating.

  2. penetrating compounds.

  3. Roll materials.

Each of them has its own characteristics. Both by the principle of operation, if I may say so, and by the nature of interaction with protected structures. The method of applying waterproofing materials also differs. Therefore, we will consider each in more detail.


The simplest and most effective way if waterproofing a concrete basement is required – both prefabricated, from blocks, and by pouring into the formwork. It consists in the fact that mastic is applied to the surface of walls and floors, after curing or polymerization, it forms a dense waterproof film on the surface of structures. There are several types of such materials:

  • Based on bitumen, with the addition of polymers or latex.

  • On acrylic resins.

  • Polyurethane.

  • Cement-polymer.

  • Latex.

The common property for them is complete water tightness. The film does not breathe, so it should not be applied to porous materials that can absorb water. Because it leads to their slow destruction.

Before applying the coating, the surfaces are cleaned from mechanical and biological contaminants (mold) and then primed with primers that enhance adhesion. If there are cracks in the walls or floor of the basement, they are expanded to a solid base and filled with self-expanding sealants with hydrophobic properties. Or the same coating from a mixture of cement and polymers.

The floor is processed completely, and the walls to the level of standing water outside. Waterproofing the ceiling in the basement is usually not done.

The coating is applied with a brush, roller or other method recommended by the manufacturer. Usually, bituminous compounds are heated, which makes working with them more difficult and dangerous. However, in any case, you need to use personal protective equipment – goggles, gloves and respirators. These compounds are quite toxic, they often include fungicides to prevent the development of mold. Water-soluble acrylic coatings can be considered the safest.


They change the properties of the materials they are applied to, preventing capillary penetration of water through them. Therefore, such compositions are used for walls made of brick, aerated concrete, shell rock or limestone. They can also process concrete, the quality and strength of which are in doubt – it will not get worse, but to some extent you can be sure that water has not accumulated in it.

Having the property of capillary penetration, such compositions are able to pass even through if the thickness of the walls of the cellar is small. After some time, they turn into an elastic gel or crystallize. This also determines the second sphere of their application – strengthening of structures during the restoration of historical buildings.

Penetrating compounds go on sale both in liquid (then they are called sealers) and in pasty form. In the latter case, they not only penetrate deep into, but also form a waterproof film on the treated surfaces.

Sealers are applied by spraying under pressure. It can be superficial through a spray gun or garden sprayer. Or deep, when the composition is fed into pre-drilled holes. In this case, the process is called injection.

Roll media

They are a base impregnated with bituminous resins. In the simplest case, this is construction cardboard. This is how the well-known roofing material is made. Currently, there are models with a fiberglass base, which is much more reliable.

For waterproofing the cellar, it is better to use models that have an adhesive base. In this case, you do not have to use an open flame in order to melt the coating and thus fix it on the structures. In principle, cold curing bituminous coatings can be used as adhesives.

Roll materials very reliably prevent not only non-pressure filtration of water, but are also able to resist its flow. The main thing is their flammability and low compatibility with food products. If you plan to store homemade canned food or root vegetables in the cellar, then you need to find a way to hide this layer. Which increases costs.


In winter, foundation structures experience heavy loads from soil displacement as a result of frost heaving forces. Therefore, in the spring, an emergency situation is not ruled out – water leaks through cracks or a loose seal in the openings for passing highways.

In this case, the so-called hydroseal is used. In fact, it is a dry cement mixture with modifying additives that accelerate curing and enhance adhesion to various materials of a similar nature – concrete, brick, limestone.

It takes from 30 seconds to a minute for a seal to rise and close. You can knead the mixture with the same water that penetrates into the basement. After complete drying, waterproof the problem area with coating and roll material.

You can also use a hydroseal in the case of planned basement waterproofing. Seal cracks, seams, pipe or cable passages with it before applying basic waterproofing materials. Get pretty reliable.

A dry basement that is not flooded during floods significantly improves the performance of the house and extends its life. And, importantly, it increases its market value. Therefore, the cost of works and materials used in waterproofing works is fully justified. They will pay off within the next two to three years.

Basement waterproofing | An example of waterproofing a basement of a private house from the inside

For those who have encountered this problem, it is obvious that high-quality waterproofing of a basement cannot be ensured with the help of coating materials.

An integrated approach to basement waterproofing

Depending on the characteristics and current condition of the basement or other underground structure, water and moisture protection of both the floor and walls, as well as waterproofing of abutment joints, may be required.

An integrated approach is needed to eliminate the causes of dampness in basements. There are very few regulatory documents on this issue; there is no clear approach to solving the problem of waterproofing a basement or similar structures. According to statistics, the wrong choice of materials for waterproofing leads to problems in 15-20% of cases, unsatisfactory quality of work – in 35-40%.

Why basement waterproofing is necessary

Problems that most often arise after a basement inspection:

  • leak through joints between foundation blocks of basement walls;
  • leaks in places where engineering communications are introduced;
  • wetting brickwork.

If you need reliable waterproofing of a basement (wall, floor, foundation) or other structures used for various purposes, such as waterproofing a concrete cellar, pay attention to the materials of the Penetron system.

Below are examples of basement waterproofing from the inside with Penetron penetrating materials, as well as self-healing and repairing leaks with Penetron and Skrepa products.

1. Treatment of joints between foundation blocks (Fig. 1)

Materials for waterproofing

for just A couple of minutes. The joints between the FBS blocks for waterproofing the basement from groundwater are sealed with Penekrit and Penetron mixtures. To prevent water from seeping through the thickness of concrete, the blocks are treated with a water-repellent Penetron penetrating mixture.

Preparing the gouge

Make a gouge along the joint using a wall chaser or a jackhammer. The cross section must be at least 25 x 25 mm. After that, clean the resulting streak from the remains of concrete with a brush with a metal support, moisten it well and apply a layer of “Penetron” as a primer (dry mix consumption is 0.1 kg / m.p. with a section of 25 x 25 mm).

Filling with Penecrit mortar

Fill the streak tightly with Penecrit mortar mixture. The layer thickness at one time of application should not exceed 30 mm. To fill a deep line, make several layers. The consumption of the dry mixture “Penecrete” for a section of 25×25 mm is 1.5 kg / m.p. If the cross section is larger, the flow rate of the dry mixture increases proportionally.

Treatment with “Penetron” mortar

The trench filled with “Penecrete” and the foundation blocks themselves must first be soaked with water to the maximum possible state and treated with the “Penetron” mortar in two layers.

2. Sealing entry points to engineering communications during basement waterproofing

There are several options for the device, depending on the design and features of the entry of the communications themselves. Below we will consider two ways to seal a pipe with a metal sleeve.

Option 1 (Fig. 2)

Materials for waterproofing

If there are leaks in places where communications are introduced during work, they must be eliminated using sealing materials such as “Peneplug” or “Waterplug”. After the leak is eliminated, sealing is carried out with the materials “Penebar”, “Penecrete” and “Penetron”.


A minimum 25 x 25 mm hole is made around the sleeve. Remove the gasket between the sleeve and the pipe if the depth is at least 75 mm. if there is no seal, it must be restored, leaving a cavity 75 mm deep. Then, clean the pipe, sleeve, and seal of concrete and other debris.

Filling the streak

Moisten the streak and work with “Penetron” in one layer. Fill the streak and compact with the Penekrit mortar. Then, the already set solution and the concrete surfaces adjacent to it should be treated in two layers with the Penetron penetrating mixture.

Filling the space between sleeve and pipe

Use Peneplug or Waterplug fast setting compound to seal water leaks.

Prepare the required amount of Penebar Braid. Before installation, degrease the pipe, and then wrap it tightly with a bundle. “Penebar” is attached to the pipe with a metal wire or clamp.

Fill the space between the tube and the metal sleeve with a mixture of Penekrit mortar, then apply Penetron penetrating waterproofing material in two coats.

Option 2 (fig. 3)

Materials used

plug”, which used only when stopping a leak. As well as special glue “Penepoxy” and dry mixtures “Penecrete” and “Penetron” for direct sealing of entry points for engineering communications.

Preparing the punch

Seal around a sleeve with a minimum cross-sectional dimension of 25mm x 25mm. Remove the seal between the sleeve and the pipe if the depth is at least 50 mm. if there is no seal, it must be restored, leaving a cavity 50 mm deep. Then, clean the pipe, sleeve, and seal of concrete and other debris.

Space filling

If water leaks occur during the waterproofing of a basement, concrete cellar or other underground structure, they must be stopped with a mixture of Peneplug or Waterplug.

Before using Penepoxy, the surfaces of the tube and sleeve must be degreased with a solvent. After that, the place is densely and constantly filled with adhesive material “Penepoxy”. In 24 hours, the polymerization depth of the adhesive is 3 mm.


Finely dampen and work with Penetron mixture in one layer. Fill the streak and compact with the Penekrit mortar. Then the resulting solution and the concrete surfaces adjacent to it should be treated in two layers with the Penetron penetrating mixture.

3. Masonry waterproofing (Fig. 4)

Penetron Penetrant is not suitable for masonry or masonry. To make such structures waterproof, it is necessary to first perform plastering, and only after that it is possible to apply the Penetron penetrating mixture.

Please note that this waterproofing method is superficial. If waterproofing is done on the inside of the basement, the stone or brickwork will continue to be damp and eventually erode. Therefore, it is recommended to work on the side exposed to water.

Surface plastering

Plastering and its application have certain requirements that must be met in order to obtain a quality and reliable result.

The composition of the mortar must consist only of cement and sand, the use of lime mortar and gypsum is not allowed. The grade of the solution must be at least M150.

  • The mortar should only be applied to masonry mesh (mesh size 50×50 mm), which is fixed and firmly attached to the surface.
  • The distance between the masonry mesh and the brick base must be at least 5-15 mm.
  • The thickness of the plaster layer must be at least 40 mm.
  • The structure of the plaster layer must be dense, without air gaps.
  • It is recommended to apply the mortar continuously without interrupting the process in order to avoid the formation of work seams.

Application of the penetrating mixture “Penetron”

Application of the mortar mixture “Penetron” on plastered surfaces should be carried out no earlier than in a day (in accordance with the requirements for plastered surfaces).

Consumption of mortar mixture “Penetron” in terms of dry mixture, taking into account the application of two layers, is 0.8 kg/m2.

Waterproofing of stone and brick structures with a mixture of “Scrape M500”

A variant of waterproofing for stone and brick structures with a dry mixture of “Scrape M500”, STO 77921756-001-2018. In this case, the grout mixture must be applied in two layers with a total thickness of not more than 20 mm. Composition “Brace Repair M500” should also be applied only to the grid (mesh size 50×50 mm, diameter 3 mm), which is rigidly attached to the surface.

When using the composition “Skrepa Repair M500”, surface treatment with the mortar mixture “Penetron” is not required.

To seal seams, cracks, seams, joints in basements, it is necessary to use Penekrit waterproofing mixture.

4. Care of the treated surface

Within three days after treatment, it is necessary to monitor the condition of the treated surface.