Basement waterproofing Costs 2021

Basement waterproofing is very important for any home as by waterproofing your basement you regain an entire floor of usable space and also make sure that your foundation prevents any flooding.

Basement waterproofing

The average cost of basement waterproofing (seal basement or foundation) comes around to £3,100. For any minor repair estimate to pay approximately £500. More complicated basement sealing jobs such as adding drains & gutters can cost over £6,500. However, as there are always a number of variables involved, basement waterproofing cost can range anywhere from £1,700 to £5,200. Per square meter expect to pay anywhere between £40 to £80.

Your basement could flood for a number of reasons but the most important step to waterproofing it is to seal it in an effective way to protect it from any water that might enter the foundations. Before deciding to proceed with any basement waterproofing method, always consult a professional waterproofing contractor.

Exterior Foundation Sealing

When looking to protect your house by keeping water outside of your basement, always start with an initial professional consultation of a licensed contractor, as you will have a better idea of what steps to take to protect your home.

The consultation might suggest solutions such as waterproofing basement walls from outside or installing a basement wall waterproofing membrane from the interior of the basement. Even if you only have crawl space, you need to prevent water from coming in. The cost of sealing your crawl space ranges from £1,200 to £12,000.

In this guide, we will try to clarify the difference between waterproofing and damp proofing, and the pros and cons of using cement, membrane and weeping tiles to seal the foundation of your home.

Waterproofing vs. Damp Proofing

Most basements are built in a way to keep out soil moisture by employing damp proofing. Damp proofing is different from waterproofing, which is meant to keep out both liquid water and soil moisture.

There are several different methods of damp proofing such as :

  • Use of damp proof course
  • Integral damp proofing
  • Surface treatment
  • Cavity wall construction
  • Guniting
  • Pressure Guniting

From the damp proofing methods, the most common is surface treatment, which professionals apply a coat by spray or hand to the outside of the wall. Surface treatment offers protection from damp soil and also cost less than other damp proofing methods. For detailed prices visit our damp proofing cost guide. Even though damp proofing protects from damp soil, it does not offer any protection against actual water leakage, so it might be a wiser investment to pay more for waterproofing.

A basement could make a great extra living room, or even a games room, home cinema or kids play area if you fancy something a little more exciting. But if you do need the extra space, it could also make a great storage area or utility room too.

If you have a lot of work to be getting on with your basement could even be converted into a home office. Or,  if you want to start thinking about expanding your family it would also make a great below-stairs bedroom for one of your loved ones. This article discusses the most common basement problems and also how it can be used in the best possible way to accommodate your needs.

Common Basement Problems

The most common cause of a leaky basement is water coming in through the joint between the floors and the walls after a rain or snowmelt. The common area for this to happen in is the corners. Water almost never comes up through a basement floor if the basement has been properly constructed. Hydrostatic pressure is caused by the build-up of surface water around the foundation. This pressure pushes water in through the corners were the floor and walls meet.

Why do basements leak?

Basement leaks most commonly occur in the joints between the floor and the walls. When there is a rain or a snowmelt hydrostatic pressure is formed. This pressure forces water through these joints. In order to prevent this type of leak proper waterproofing must be installed.

Waterproofing Your Basement

You should begin the basement waterproofing process outside. You need to eliminate areas where water can collect around the exterior of the home. Surface water goes through the soil and down to your foundation when it builds up. Check to see whether the water in low lying areas flows away from the home. Sometimes it will be necessary to install a drain system that pulls water away from your home. Always check your basement waterproofing after a flood.

Benefits of basement waterproofing

Waterproofing your basement will protect your home from this type of leaks. Basement waterproofing takes place both inside and outside your home. This first step is to look for areas around the outside of your home where water collects near the foundation. You always want the water to flow away from your foundation. Make sure that your downspouts direct all water at least eight feet from your foundation and that gutters are in good condition and free from debris. You can prevent some leaks by ensuring that water is directed away from your home’s foundation.

Cement Waterproofing

Applying cement is probably an easier way to keep water out by applying it directly to the exterior walls. You get a denser and stronger concrete when water evaporation is slowed down during the curing process. You can use any sealing material as a curing sealer instead of using a temporary sealer or water mister. Capillaries will naturally develop in the concrete as it cures.

After it has cured for at least 28 days you should apply two coats of a sealing material to both the slab and the walls. This basement waterproofing method bonds and strengthens the concrete while at the same time keeping vapour, radon, and water out of your basement.

The mortar on concrete block walls should cure for at least 14 days before a sealer is added. Regularly check any joints or cracks in your concrete for leaks. One easy way to test for moisture leakage in your basement waterproofing is to tape down the edges of a piece of aluminium foil with duct tape in an area where you suspect moisture. In a few days check back to see if any moisture is lurking under the aluminium foil.

Foundation Waterproofing Membrane

Foundation Waterproofing Membrane is the most effective but also most expensive basement waterproofing method to a dry home. The cost of installing a foundation waterproofing membrane starts from £11,500. The process involves adding drainage panels, excavating work and fitting membranes onto your exterior wall.

The membranes need to be installed by a professional as they consist of rubberized asphalt, which is laminated to a waterproof film. This method of foundation waterproofing is very effective and long-lasting when implemented right and makes an ideal solution for basement waterproofing. If you have a crawl space, it still makes a great option, even though it is mostly meant for full basement usage.

Exterior Weeping Tiles

There is also the option of stopping the water from entering your walls by using weep tiles, which are plastic pipes with regularly punches holes. Weeping types are particularly good for people living in areas with damp climates. They work well for houses built with concrete foundations, basements and crawlings. The cost to install a weeping tile system on the exterior walls of your house comes around to £80 to £130, depending on the level of accessibility and the excavation depth.

Cavity Drainage System (Tanking)

The water from the walls is collected in a well and then pumped out of the building. For this type of waterproofing installation, a membrane will be installed to the walls and the floor keeping the water out of the room but instead of just pushing the water back, it is drained and removed from the basement with a pump. For basements with drainage and membrane systems, there are no demands regarding structural stability of the basement construction, therefore it is suitable for most basements.

Interior Basement Waterproofing

Waterproofing your basement walls from outside is not enough. You also need to protect the interior walls of your property. There are several choices available such as concrete coating, silicate sealers, special water repellent paint and a vapour barrier for your oral space.

Concrete Waterproofing & Foundation Coatings

All the waterproofing methods applied to exterior basement walls from outside can also be put to use to seal the interior of your basement. You can choose to apply a thick, permanent coat of concrete, to prevent water from getting into the interior of the basement, even if it passes through the exterior barriers. The cost of internal concrete waterproofing is a little less than the exterior, as there is no need for excavation. Basement waterproofing contractors charge between £350 and £700.

To further protect your basement, you can also use acrylic/epoxy products from Perma-Seal, as they provide a very effective and durable solution, that can significantly improve the life of your concrete floors and walls. Damp proofing professionals usually charge between £20 and £90 per square meter.

Silicate Concrete Sealers

Silicone sealers is another option, which works in a different way. In opposition to concrete which is applied to the top of the external or internal wall of the basement, silicate sealers penetrate the walls on which they are applied. Without changing the appearance of your walls, silicon sealers interact chemically with the concrete, keeping the wall dry, while allowing moisture to escape the basement. Expect to pay between £25 to £75 per square meter for labour and materials.

Basement Waterproofing Paint

Acrylic waterproofing paint is also a great way to keep your basement walls dry by keeping moisture away.  This option is more suitable if it is done as a Diy job and you should think of it as a thicker version of everyday paint. You can easily buy this acrylic-based waterproofing paint yourself from most stores from £15 – £20 per litre, depending on the quality.

Crawl Space Vapor Barrier

If you only have a crawl space, you need to be very careful as it can be damaged severely by water or moisture penetrating the walls or floor of your property. However, you can take several actions to make sure that this won’t happen.

By having a professional waterproofing contractor install a vapour barrier (plastic sheet used to prevent moisture from entering the house), you can protect your crawl space from being damaged by moisture or liquid water. The cost of professional installation for a crawl space barrier usually ranges from £1,150 to £2,350, depending on the the size of the crawl space and the thickness of the plastic sheet.

Best Waterproofing Method For Basement Conversions

Many newly built basements already come with waterproofed walls and floor. For basement conversions, the best choice for waterproofing depends on the existing structure of the basement walls and floor: minor weak points can now be fixed without having to tank the whole basement.

More serious insulation problems will, on the other hand, usually require extensive waterproofing. Also, there are different grades of waterproofing basement conversions: for storage rooms a higher level of humidity is tolerable than for rooms where people would live, sleep or eat.

Usually, a type of drained cavity system with membranes and a pump will be the best choice for waterproofing basement conversions, with differences only in the type of membrane applied to the walls and the power of the pump.

Moldy Basements

Basement waterproofing

Almost all homeowners with basements should do basement waterproofing to deal with mould. Keeping moisture out of your basement is an almost impossible task. Leaks often result from cracks in the joints of the walls and floors. You will see mold and mildew cause damage to your basement structure, as well as any items in the basement if moisture is not quickly removed. You can tell you have mould in your basement if it smells musty or you see mould.

How Does Mold Form?

Areas that retain moisture have a tendency to allow moulds to form and grow. You will see the growth of mould in walls, floors, and basement carpeting if any moisture seeps into the basement. Mould can grow quickly, forming in any moisture that is left in your basement for more than a day.

Preventing Mold Growth

The only way to prevent mould growth is to fix moisture problems as mould is capable of growing on any wet surface. You need to apply a waterproofing coating to your walls and floors since they are the most susceptible to moisture. You must keep things dry, sometimes you might need a basement dehumidifier to prevent mould from taking over. You have the least possibility of mold growth in the areas that are the driest. To prevent the re-growth of mold in an area you have already cleaned it is a good idea to disinfect the spot and dry it out as quickly as you can.

Removing Mold From Your Basement

You need proper equipment and gear in order to safely remove moulds from the surface of your basement walls and floors. You should always wear gloves and eye protection and immediately wash the clothes you were wearing. You can reduce the spread of airborne mould spores by dampening the area prior to cleaning it. While it will not work for all surfaces it is generally a good idea to scrub the area with detergent. The best thing to do with a mouldy carpet is to throw it away. Carefully disinfect the entire area after the mould has been removed. Dry the cleaned area as quickly as possible. If there is not enough natural ventilation to allow for quick drying consider using a dehumidifier​ or heater.

Painting Your Basement Floor

basement flooringPainting your basement floor is an excellent way to help seal it and prevent rusting. Sealing your basement floor can protect it from stains and also acts as a great primer if you would like to paint the basement flooring as well.

  • Thoroughly clean your basement floor with a commercial concrete cleaner, being sure to follow the manufacturers instructions carefully.
  • You may need to repeat step one in some areas with stubborn stains.
  • It helps to allow the cleaner to soak for 30 minutes before beginning to scrub.
  • Put the sealer in a large tray once the floor is completely dry.
  • You will need to use a brush to get into the edges but can use a medium nap paint roller with a long handle for the rest of the floor.
  • You want to make sure you have a thick even coating, without puddles.

Since sealer can stain surfaces always be sure to mask off areas that you don’t want to be covered. Let the sealer dry as per the manufacturer’s instructions. During this time you should clean your tools in soapy water. It is now time to mix the two-part epoxy paint which has been specifically designed for concrete floors, again carefully following the product directions. The direction will indicate a period of time during which the paint must rest before it is applied.

Mask any areas that you do not want to get painted. Get the paint into the corners and edges with a paintbrush or trim pad. You can apply the paint to the rest of the room using a roller with a long handle. You can giver your floor a non-skid finish, as well as a decorative touch, with the addition of paint chips. You will need to apply these chips to an area while it is still wet prior to beginning the next section. To ensure that the cellar floor is completely dry do not walk on it for at least 12 hours.

A well-painted basement flooring is the perfect finish and does not need to be covered with carpet or other floor coverings. You have also protected your floor against stains and other types of damage.

Basement Flooring Options

basement flooringMany people neglect the important living space that their basement could offer. With a little creativity and time, you should be able to turn your unused space into a great family room or den. When it comes to your basement flooring both moisture and warmth are an issue. Even if your floor looks dry, take a closer look for cracks or other openings that could allow moisture to enter and get trapped beneath your new flooring. You have many options for your basement floor depending on your personal style and budget.

Engineered Hardwood Floors

Three to five layers of various hardwoods are used to make this flooring. Each new layer is placed at a 90-degree angle to the layer beneath it. This prevents a lot of the issues that are associated with moisture such as expansion, contraction, and warping. To create a tight bond between each layer they are glued and then laminated under heat and pressure. These floors are easy to maintain and add a sense of beauty and warmth to your basement space.

Slate and Ceramic Tile

While both these materials can be cold to the touch, a few well-placed throw rugs should fix that. It is easy to install ceramic tiles over your existing concrete floor. Like concrete, your ceramic tiles are vulnerable to the conditions underneath them. You will need to take measures to protect your tile from the impact of any cracks in the floor. A basement floor that has steel rods running through the concrete will help protect your ceramic tiles from the cracks and fractures that movement can cause. Another great idea is to have the concrete floor and the tiles move separately by installing a crack isolation membrane under your tiles. Staining or painting your concrete sub-floor is another option.


You can definitely add warmth and beauty to your cellar with the addition of carpeting. To help them resist microbes your carpet will need to be regularly cleaned. Those with asthma or allergies may want to think twice before installing carpet in their basement as it can cause irritation. While dehumidifiers will reduce basement floor condensation they will not get rid of it entirely. Area rugs are a great alternative for those who want to avoid the risks posed by installing carpet. Area rugs can be much more easily cleaned on a regular basis.


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