Basement waterproofing costs $6 to $15 per square foot, depending on the basement size, home's condition, and waterproofing methods. Higher fees apply for structural foundation repairs. Exterior waterproofing methods are always more effective because they prevent all water from entering a basement.

• Interior basement waterproofing costs $4,500 to $10,000 on average for retrofitting a drain system under the basement floor. This solution is ideal when the home's location doesn't allow enough space for adding more exterior drainage.
• Exterior basement waterproofing costs $10,000 to $15,000, including excavation and installation of French drains underground near the home's footings.

Basement waterproofing involves applying sealants, installing drains, and setting up barriers to prevent water intrusion. Experts also repair existing basement damage and may adjust the yard's gradient to redirect rainwater away from the home.

The most obvious way you'll know that your basement needs waterproofing is if water leaks into the basement or the walls get damp when it rains. A bowing wall or warped doors that get moldy are other common indications.

Additional signals you need waterproofing are:

• Cracks in the basement walls or floor
• Chalky residue on walls
• Water stains
• Musty basement odors

Many benefits of waterproofing your basement that are worth the cost include:

• Preventing structural failure of your basement walls
• Eliminating mold growth
• Converting your basement into a dry and livable space
• Raising the value of your home before selling it

Waterproofing a basement is cheapest for more temporary solutions like painting the floors and walls with high-quality sealants. If you have bowing walls or extra-large cracks in the walls, then seek a professional's advice immediately since the wall could collapse.

Some inexpensive DIY ways to start waterproofing also include:

• Using bags of fill dirt to make slopes that send rainwater away from the home.
• Installing the longest downspouts you can to protect your foundation.
• Cleaning and maintaining your gutters so that they won't overflow.
• Adding splash guards to the gutter system.

Out of all the waterproofing methods, the best ones are those that address water drainage over your entire property.

These projects can include many steps according to your conditions:

1. Grading and re-sloping your yard can be an essential first step to stop hydrostatic pressure from building up outside your foundation walls, which weakens them.
2. Any structural issues in the foundation require immediate attention to reinforce the building. This step can involve adding new mortar to brick or block foundations, or even installing a new beam to stop wall failure.
3. Installing or improving the existing drainage system is essential, especially if you live in areas prone to flooding.
4. Contractors may also add a drip edge trench of gravel around the home's perimeter to move rainwater away faster.
5. Applying sealants to the basement interior is typically the final step.

A basement waterproofing company typically takes 1 to 3 days to finish an area up to 300 square feet. Allow up to 7 days when more excavation work is necessary. The amount of time it takes varies according to property conditions, extent of the damages, and the method.

A complete exterior basement waterproofing lasts more than 25 years for adding a new French drain around the perimeter, regrading the yard, and applying a water barrier sealant to the foundation. Most interior basement waterproofing lasts 10 to 25+ years depending on the installation quality.

Applying a sealant to the interior alone is a temporary solution that doesn't stop water pressure from building outside the basement walls.

You can increase your home's value by waterproofing the basement in many places, and the total value added varies according to the criteria of the property appraiser.

If a buyer finds you have water leaks in the basement during the home inspection, then they often refuse to buy the home when expensive repairs are likely.

Many homeowners insurance policies can cover general repairs after a pipe bursts or after a flood, if you have flood insurance in the plan. However, insurance typically doesn't cover installation of a complete waterproofing system. Confirm the terms and conditions of your coverage by reading your policy.

Before hiring a basement waterproofing company near you:

• Request 3+ quotes from licensed, bonded, and insured companies to compare.
• Check if they have credentials from the Basement Health Association, the EPA, or the National Association of the Remodeling Industry.
• Verify if they're part of any local building or plumbing associations.
• Read their past reviews on HomeGuide and Google.
• Confirm if the contractor has 5+ years of experience.
• Get an itemized estimate and contract copy before the job starts.
• Avoid hiring the cheapest contractors who might have low-quality service.
• Never pay in full until the job is complete.
• Be cautious about hiring a company insisting their bid is valid for a limited time.

Ask these key questions to help you pick a good basement waterproofing company:

• How long have you been in the basement waterproofing business?
• What's your base service fee for a basement inspection?
• Can you provide references from past clients with similar projects?
• How is water getting into my basement?
• Is this type of water leak common in my neighborhood, and if so, why?
• What experience do you have with waterproofing basements similar to mine?
• Are there structural problems that could cause wall failure?
• Can you recommend an engineer if my basement walls are unstable?
• Which waterproofing methods do you recommend for my basement and why?
• Does your estimate cover materials, labor, delivery fees, and cleanup?
• Will I need to pay extra to repaint my walls or floor afterward?
• How long will this waterproofing job take?
• Should I be home during the work?
• Will you give me a written estimate, contract, and timeline for the project?
• What do you do if unexpected problems arise?
• Can you offer me a guarantee on your work, and if so, how long is it for?
• How should I prepare for your crew?