What Is Basement Waterproofing and How Does It Work?

Basements can add value to your home and serve as either additional storage space or living area, but they’re prone to moisture build-up and water intrusion that can eliminate their usefulness entirely. Not only is a damp basement inconvenient, but it can also be dangerous, causing structural damage to your home and decreasing your indoor air quality. In this guide, we’ll explain what basement waterproofing is, how it can solve your moisture issues, and the different methods of waterproofing you can use.

What Is Basement Waterproofing?

The term “basement waterproofing” refers to any number of techniques homeowners can use to keep water away from their foundation and remove any water or moisture that does get inside. There are a wide variety of foundation waterproofing methods you can use, with the best one usually depending on the underlying issue and how moisture is getting into your basement.

How Does Basement Waterproofing Work?

Basement waterproofing works a few different ways. Some of the most effective and permanent methods for waterproofing a basement involve keeping runoff and groundwater away from your foundation walls entirely. These are considered preventative measures.

• French drain

• Footing drain

• Gutter, downspouts, and downspout extenders

• Damp proofing

• Soil gradation

• Foundation crack sealing

• Waterproof foundation paint

• Vapor barrier

There are also reactive measures that you can use on their own or in combination with preventative measures to remove any moisture or water that does get inside.

• Sump pump

• Basement floor drain

• Dehumidifier

Pros and Cons of Waterproofing Your Basement

Since most basements leak or allow moisture in at some point, basement waterproofing is not only beneficial but is usually necessary to keep your underhome area dry. You’ll mostly benefit from waterproofing your foundation, but there are some downsides to consider as well.

Pros

• Keeps your basement dry

• Reduces the risk of mold growth

• Reduces the risk of rotting building materials

• Reduces the risk of related structural damage

• Often lowers your electric bills

• Makes your living area more comfortable

• Improves your indoor air quality

• Makes basement safe to use for storage or as living area

Cons

• Can be quite expensive

• Can require time-consuming excavation around your basement

• Potentially dangerous if it involves mold removal

• Often requires help from a professional

Main Types of Basement Waterproofing

There is a wide variety of basement waterproofing solutions you can employ, and the right options for you will depend on the underlying problem, the extent of the issue, your soil quality, the climate in your area, and more. Ultimately, there isn't a one-size-fits-all approach. Often a combination of factors are at work, and you’ll need to use more than one waterproofing technique for long-term effectiveness.

Unless you’re an expert, this isn’t a project you’ll want to handle yourself. We recommend you contact a basement waterproofing company near you to determine which of the following interior and exterior basement waterproofing methods would combine to keep your underhome area protected and dry.

Interior Basement Waterproofing Solutions

There are quite a few things you can do inside your basement to help mitigate moisture issues and keep the space dry.

• Install a sump pump to remove standing water.

• Install a basement floor drain to remove standing or pooling water.

• Install a dehumidifier to remove moisture from the air.

Interior basement waterproofing techniques rarely require as much work as exterior solutions because there’s usually easy access to the area without excavation. For the same reason, they’re generally more affordable. Since these options all deal with water and moisture that have already gotten in through your concrete floor or foundation walls, they’re all considered reactive solutions.

Interior Sealant Application

Applying a waterproof paint or sealant to your basement's interior walls and floors is simple and economical, and it can prevent moisture from seeping through any fine cracks or small holes in the foundation.

This preventative solution usually isn’t enough on its own, as it doesn’t address the underlying reason for the water seepage. Also, these sealants don’t form tight seals on painted walls and won’t work on wide cracks, so many foundation contractors couple this with crack sealant for full protection from moisture.

Plus, waterproof paint can sometimes be problematic in its own right. “Many times, sealants will trap water in the foundation walls and can create more problems down the road,” says Angi expert John Bryant of AquaGuard Waterproofing Corp in Beltsville, MD.

Interior Vapor Barrier

A vapor barrier is a plastic sheet that a contractor installs over the walls and floor of the basement to encapsulate it and prevent moisture from accumulating in the air.

Vapor barriers are generally only suitable for unfinished basements, and they aren’t a great solution because moisture can still get trapped between the foundation and the barrier. However, they should improve your home’s energy efficiency and your indoor air quality.

Exterior Basement Waterproofing Solutions

Exterior waterproofing solutions are generally proactive because they deal with water and moisture before they have a chance to interact with your concrete foundation and seep inside. There are a few options for exterior waterproofing.

Exterior waterproofing solutions are often the most expensive and complex methods and require professional help. Some require excavation, which can be time-consuming and costly, and depending on how much excavation you need, you could end up with large dirt patches in your yard that require regrowing grass.

Exterior Sealant Application

There are two exterior sealing techniques a waterproofing professional can use to reduce the risk of water in the soil interacting with your concrete foundation.

• Waterproofing membrane

• Waterproof foundation paint or damp proofing

A waterproofing membrane is a solid rubber sheet that sits between your foundation and the soil. This keeps moisture away, but it isn’t a standalone solution in most cases because it won’t protect against deep moisture or hydrostatic pressure from expanding soil. Waterproof foundation paint is similar to the interior paint mentioned above.

Both of these methods require excavation around your entire foundation, which is time-consuming and expensive. Plus, if the soil isn’t backfilled and compacted properly by a professional, you could end up with structural damage.

What Can Cause Water Damage in Your Basement?

The first step to keeping water out of your basement is identifying the cause of the basement water issue, and there are quite a few things that can cause water and moisture build-up in basements.

• Clogged or broken gutters

• The existing exterior waterproofing medium is no longer effective

• Deterioration in sewer lines or main water lines

• Poor soil, landscape sloping, or drainage issues preventing water from flowing away from your home

• Cracks or other imperfections in your basement walls, floors, or windows

• Clogged drains

• Foundation shifting

• Condensation from excess humidity or dampness

• Poor initial foundation construction

• Tree roots or shrubs holding water against your foundation

• Interior plumbing leaks

• Moisture from basement bathrooms or kitchens

• Moisture from basement exercise areas

Most Common Foundation Issues

According to data from Angi, the most common foundation problem is basement flooding, making up around 29% of reported issues. Another 20% of homeowners reported issues with excessive dampness, while 15% mentioned problems with mold, mildew, and fungus.

Average Costs for Basement Waterproofing

The average cost for a complete basement waterproofing solution is around $5,500, but your total could range anywhere between $1,000 and $30,000, depending on how extensive your problem is and the number of the solutions discussed above your home demands.

DIY vs. Hiring a Pro

It’s possible for just about any homeowner to tackle some of the basement waterproofing methods mentioned above, but others you should always leave to the professionals. Some of the things you can probably handle yourself include:

• Grading soil away from your foundation

• Sealing hairline cracks in your foundation

• Installing downspout extenders

• Installing a French drain

Some basement waterproofing methods are complicated and can cause additional damage to your foundation if done improperly. We recommend leaving the following methods to a professional:

• Installing a footing drain

• Installing a sump pump or basement floor drain

• Installing damp proofing

• Installing an exterior foundation membrane

• Installing a vapor barrier

• Sealing wide or uneven foundation cracks

• Installing a gutter system

• Setting up a dehumidifier

Additionally, it’s a good idea to have a professional carry out a basement inspection to assess your home and determine which waterproofing methods will work together to solve your water or moisture issues, even if you end up doing some of them yourself to save on labor costs.