The Complete Guide to Basement Waterproofing

By: Julie Thompson | Affiliate Disclosure

Basement waterproofing is the best way to prevent excess water and moisture from getting into your basement. It can be completed when a home is newly constructed or when you buy a house. Regardless of when you decide to waterproof your basement, it’s always recommended to complete this task before any water damage occurs. This preventative measure can lengthen the life or your home and help you avoid costly and time-consuming repairs.

Signs you need basement waterproofing

Basements are naturally susceptible to moisture build-up. Some common causes of a wet basement include:

  • Poorly maintained gutters—If your gutters are clogged with debris or improperly installed, they won’t be able to direct rainwater away from your foundation.
  • Hydrostatic pressure—When rain and groundwater drain toward your basement and form puddles around your foundation walls, this water forces its way through open cracks in the foundation. This can cause significant damage if not addressed quickly.
  • Poor drainage systems—If you’re using the wrong soil in your garden or don’t have a proper drainage system, water can pool around your foundation walls and seep into your basement.
  • Improper exterior slope—The ground around your foundation should slope away from the home, not toward it. If it’s sloping toward your home, this could cause water to build up and puddle around your foundation.

In addition to the previous issues, if you notice any of the following signs in your basement, consider waterproofing it as soon as possible:

  • Musty smells
  • Mold
  • Standing water/condensation
  • Higher than average humidity levels
  • Cold temperature
  • Floor cracks
  • Basement walls bulging inward

After determining signs of a leak or moisture build-up in your basement, a simple test will help you determine whether the seepage is on the inside or outside of your walls.

  1. Tape a sheet of foil or plastic wrap to your basement wall. After a few days, check to see if there’s condensation on either side.
  2. If the condensation is located on the wall side, the problem is an exterior issue and may require a professional contractor to check if your gutters and downspouts are working properly.
  3. Condensation on the side facing the basement is a sign of interior seepage. The remedy for this is determined by the amount of moisture and condition of your basement walls. It can range from purchasing a dehumidifier to installing interior drainage systems.

Types of basement waterproofing

Although there are several ways to apply basement waterproofing to your home, here are three of the most common methods:

Interior waterproofing

This type of waterproofing is the easiest and most affordable method and involves performing work from the inside of your home. Keeping your basement dry with interior waterproofing generally involves using a sealant or waterproof coatings to prevent condensation.

Exterior waterproofing

Exterior waterproofing is done from the outside of your home. This can be as simple as cleaning and repairing gutters and downspouts or it can be more time- and labor-intensive, involving processes like digging trenches to improve water drainage or coating the exterior walls of your home with a waterproof barrier.

Drainage waterproofing

Drainage issues are a common cause of basement moisture. This method can involve repairing an existing drainage system or adding a drainage system to pull water away from your house.

An effective waterproofing system will combine all three basement waterproofing solutions.

How to waterproof your basement from the inside

If it’s been determined that the outside of your basement is watertight, the water seepage may be coming from an interior water source. General dampness could also be the culprit, which can be solved by purchasing a dehumidifier.

Materials

  • Waterproof sealants or basement waterproofing paint
  • Spray foam (to seal drainage and electrical)
  • Concrete filler (to seal any cracks in the basement walls or flooring)
  • Putty knife
  • Vapor barrier
  • Dehumidifier

Instructions

  1. Examine your basement for any cracks, fissures, or holes in the walls and check around windows and doors.
  2. If you find any small openings, use a putty knife to caulk them with a concrete filler.
  3. For larger openings, use spray form to create a layer of insulation. Once this is complete, install a vapor barrier in front of the insulation to prevent water vapor from diffusing back into the wall.
  4. After the holes have been covered, use a waterproof sealant or paint to prevent any moisture from seeping in.
  5. Run a dehumidifier in the space for a few days to get rid of any lingering moisture.

How to waterproof your basement from the outside

If you’re still dealing with moisture after interior waterproofing, you may have an exterior issue. If this is the case, consult with a professional to help you safely and efficiently waterproof your basement. Note: the contractor might have to secure a permit from your local building authority before starting the job. 

Materials

  • Excavator
  • Professional tools and machinery
  • Waterproof sealant (with a polymer base)
  • Fill dirt
  • Grave

Instructions

  1. Start at the downspouts and gutters. If the downspouts and gutters are clogged with leaves or debris, remove the blockage. Clogged gutters can lead to oversaturated soil or puddles around the foundation of the home and cause water to seep into weak spots in your basement walls.
  2. Work with a contractor to excavate the soil around your home. Heavy tools and machinery will be needed for this, so don’t try to attempt this job on your own.
  3. Once the soil has been removed, new drainage tiles or a French drain system should be installed.
  4. During this construction process, a waterproof sealant should be applied to the exterior walls.
  5. Fill dirt and gravel should be applied as a final step to direct water away from the home and allow for proper drainage.

How to install a drainage system

Since drainage problems are a common cause of underlying moisture in your basement, having proper drainage around your home is essential to keep your basement dry. If you see large cracks in your basement floor, this is a sign of water pressure on the foundation. If the cracks get larger or are recurring, you’ll need to take action by installing a drain tile or other drainage system on the inside of your home.

Materials

  • Soil with good drainage
  • Fill dirt
  • Gravel
  • Sump pump or other professional drainage system
  • Caulk
  • Excavator
  • Professional tools and machinery

Instructions

  1. Examine the soil around your house and make sure it drains easily and doesn’t retain any moisture. Soil with large particles that are loosely spaced drains more easily than soil with smaller particles.
  2. A contractor will have to excavate the soil and dig a seven- to eight-foot drain tile trench or sump pit around your foundation.
  3. Once the trench is complete, the contractor should install the sump pump in your basement. As they’re installing the system, patch any holes you find in the foundation with caulk.
  4. Cover the trench with fill dirt and gravel to help with drainage.

How long does basement waterproofing take?

Professional basement waterproofing can take anywhere from a couple of hours to a couple of weeks. If you’re doing interior repairs, the time it takes will vary on your skills and level of expertise.

Here are a few common tasks involved with the process and the estimated time it takes to complete each:

  • Crack injection—two to three hours (dependent on the amount of cracks)
  • Sump pump installation—two to four hours
  • External crack repair—four hours to two days (dependent on the amount of cracks)
  • Internal dewatering system—two to five days
  • External dig—two days to two weeks

Keep in mind this doesn’t include the wait time to start the project or the time it takes to get a building permit if one needs to be obtained.

What should be avoided during basement waterproofing?

When going through the process, avoid these materials:

  • Tar—This isn’t an effective waterproofing material as it can become brittle and crack.
  • Plastic—This isn’t recommended for basement walls as moisture can permeate through the material.
  • Limestone—This isn’t recommended for backfill.
 

DIY or Hire?

While you can do simple fixes, such as purchase a dehumidifier to get rid of musty smells or seal the condensation from concrete walls, it’s not recommended to take on basement waterproofing as a DIY project.

DIY

  • Running a dehumidifier and caulking holes are quick, temporary fixes.

Hire

  • Exterior issues may require professional skill, tools, and expertise.
  • Professionals will be able to determine the exact cause of leaks.
  • Hiring a professional prevents you from making a mistake when waterproofing yourself, saving you time and money.

How to hire a contractor

Here are a few tips to help you hire a trusted professional to help you with basement waterproofing:

  • Gather estimates from several contractors in the area, compare quotes, and look for key items in the contract, such as payment schedules, guarantees, and fine print.
  • A good waterproofing company should provide you with a guarantee or warranty for their work, especially if they’re going to alter your basement floor, walls, or foundation.
  • Avoid companies that have aggressive sales tactics—these companies might be selling you products and services you don’t need.
  • If there aren’t many options for basement waterproofing in your area, seek out landscaping companies that may offer drainage services.

A highly rated basement waterproofing contractor can be found by completing a simple search online at the Basement Health Association or Consumers’ Checkbook.

Frequently asked questions

Is basement waterproofing covered by insurance?

If your basement has water seepage due to an internal source such as a broken appliance, a leaky water heater, burst pipes, or overflowing fixtures, it will most likely be covered by your homeowner’s insurance.

If the water damage is from an external source such as groundwater, heavy rainstorms, or sewage backups, it is less likely to be covered. Damage from external water sources can typically be covered under seasonal home maintenance, so you should periodically check for cracks in your basement floor and wall and evaluate moisture levels to prevent major problems from occurring.

If you already own a sump pump to help with water flow, check to see if it’s covered under a home warranty. If not, you may be interested in adding the system to your policy.

Note: Flood insurance might not guarantee coverage.

How much does it cost to waterproof your basement?

Basement waterproofing products and services you need can vary depending on the issue. Here are a few common costs (from least to most expensive):

  • Concrete sealers—$20–$40 per 100 square feet
  • Insulating water pipes—$50–$100
  • Dehumidifier—$250+
  • Gutter replacement—$300+
  • Cracks in foundation—$500–$15,000
  • French drain—$6,000–$10,000

Note: The level of water damage in your basement, the company you hire, and the quality of materials used to fix your issue can affect the overall cost.

When should I waterproof my basement?

Ideally, you should waterproof your basement if you notice any signs of moisture present. Try to complete repairs in a dry season, so you don’t add water to the current build-up.

How long does basement waterproofing last?

Waterproof primers and sealants might not be permanent, but they should last at least 10 years (most products have a warranty guarantee). Professional basement waterproofing should last for years. To help your waterproofing last, you’ll need to perform routine maintenance.

How to prevent moisture build-up in your basement

  • Always keep your gutters clean (remove debris once every three months), especially in the fall when leaves are more prevalent. You can install gutter screens to keep debris from piling up or extend downspouts away from the house to prevent standing water next to your foundation.
  • If you’re using a dehumidifier, empty any residual water from the unit and clean the filters once every couple of weeks. By taking good care of your dehumidifier and not using it 24/7, the unit should last three to five years.
  • Assess the slope of the land around your home. Any dirt that slopes toward your home will help water seep into cracks or weaknesses in your foundation and basement walls.
  • Examine your basement windows and make sure they’re properly sealed.
  • Use an external pipe on the outside of your home to divert water to a sump pump.

Is waterproofing your basement worth it?

Keeping water away from your home’s foundation is essential for the longevity of your home. Waterproofing your basement can prevent future structural problems to your house and block flooding that could ruin your priceless possessions. To get started, compare professionals in your area and choose a contractor that you trust. 

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