Most homeowners first discover a basement water problem the same way: a puddle after a heavy rain, a damp smell that won’t go away, or that first unsettling line of water along the base of a wall. It’s stressful, it’s inconvenient, and it raises the same question every time — how bad is this, and what do I need to do?

At Main Line Waterproofing, we’ve spent more than 15 years helping homeowners across the Main Line and Greater Philadelphia area get clear, honest answers. We don’t overcomplicate things or push the biggest job. We look at the home in front of us, identify the real source of the problem, and recommend the solution that actually works.

For most basements, that solution falls into one of two categories: Exterior Basement Waterproofing or Interior Pressure Relief Systems (Interior French Drains).

This page walks you through both options in detail, helps you understand the differences, and explains why many homes in Ardmore, Bryn Mawr, Haverford, Wayne, Villanova, Gladwyne, Devon, and similar Main Line communities face these issues more often than you might expect.

If you’re experiencing water in your basement, contact Main Line Waterproofing today to schedule your free assessment and keep your home dry for good.

Why Basement Waterproofing Matters So Much on the Main Line

The Main Line is full of beautiful, older homes with character — stone foundations, fieldstone walls, slate roofs, and decades of layered history. But those same features also make these homes more prone to water intrusion.

Some of the most common challenges we see across the Main Line include:

1. Older Stone Foundations

Neighborhoods like Bryn Mawr, Haverford, Wynnewood, and Ardmore are packed with older homes built with stone or block foundations. These foundations are strong, but they are porous and naturally allow moisture to move through.

2. High Water Table + Heavy Clay Soil

Areas such as Wayne, Devon, Berwyn, and Gladwyne often sit on clay-heavy soil that doesn’t drain well, creating hydrostatic pressure — one of the biggest causes of basement water problems.

3. Sloped Lots and Large Estates

In places like Villanova and Gladwyne, larger properties and steep slopes push water toward the foundation during storms.

4. Aging Waterproofing Systems

Homes built in the mid-1900s in communities like Havertown, Narberth, and Paoli often have outdated or failing waterproofing systems that were never designed for today’s heavier rainfall patterns.

The good news? All of these issues can be addressed — but the right solution depends on whether the water is entering through the walls, the floor, or both.

Let’s break down the two main approaches.

 

Exterior Basement Waterproofing

The only solution that prevents water from entering your home.

Exterior waterproofing is the strongest and most comprehensive method of basement waterproofing. It works by creating a barrier outside the foundation so moisture never has a chance to enter.

How Exterior Waterproofing Works

The process involves several steps:

1. Excavation: We dig down to the foundation footing — often 6 to 10 feet deep, depending on the home and grade.
2. Cleaning & Inspection: We expose the exterior wall, inspect it for cracks, and prep the surface.
3. Waterproof Membrane Application: A high-quality waterproof membrane is applied to seal the foundation.
4. Protective Insulation Layer: A drainage or insulating board (depending on conditions) is added to protect the membrane and guide water downward.
5. Exterior French Drain (When Needed): A perforated pipe is installed along the footing to redirect water away from the home.
6. Backfilling: The area is carefully restored with proper grading to ensure water flows away from the structure.

This method stops water at the source — ideal for homes battling strong hydrostatic pressure or chronic seepage.

Why Exterior Waterproofing Is Popular in High-End Neighborhoods

Exterior waterproofing is commonly recommended in communities like Villanova, Gladwyne, Bryn Mawr, and Wayne, where:

• Larger lots allow for excavation
• Foundations are older or deteriorating
• Homeowners want the longest-lasting solution
• Finished basements need higher protection
• Additions or remodels require preventive waterproofing

It is the more expensive option, but it’s also the option that delivers the most complete protection.

 

Interior Pressure Relief System (Interior French Drain)

The most practical, cost-effective solution for many homes.

Interior Pressure Relief Systems, or Interior French Drains, are designed to manage water after it reaches the foundation — specifically the hydrostatic pressure coming from under the floor.

How an Interior PRS Works

The installation typically includes:

• Cutting a narrow channel around the full or partial perimeter of the basement
• Removing concrete and digging a small trench
• Adding filter fabric, stone, and perforated piping
• Connecting the piping to a sump pump system
• Re-pouring the concrete for a clean finish

Instead of preventing water from reaching the foundation, this system manages it safely and efficiently — keeping your basement dry without exterior excavation.

When Interior Systems Are the Best Option

Interior PRS systems are extremely effective for:

• Water coming up through floor cracks
• Water pooling where the floor meets the wall
• Basements with limited exterior access
• Homes with attached garages, patios, or hardscaping
• Crawlspace-connected basements
• Partial-perimeter issues
• Budget-sensitive projects

Many homes in Ardmore, Havertown, Narberth, Drexel Hill, and Media benefit from interior systems because yards and structures often make exterior work challenging.

 

Exterior vs. Interior Waterproofing: Which One Do You Need?

It all depends on where the water is coming from.

Exterior Waterproofing is best when:

• Water is seeping through foundation walls
• There is heavy or consistent hydrostatic pressure
• The home has an older stone foundation
• You plan to finish the basement
• The property layout allows for excavation

Interior PRS is best when:

• Water is rising up from the floor
• The basement shows signs of hydrostatic pressure
• You have limited access for exterior work
• Only a small section of the basement is affected
• You want a cost-effective, less invasive solution

Sometimes, the best solution is a combination of both

Homes in Gladwyne, Devon, Berwyn, and Villanova often require hybrid approaches due to complex water patterns, steep lots, or porous stone foundations.

 

Common Signs You Need Basement Waterproofing

If you’re seeing any of the following, it’s time for an assessment:

• Water pooling after rain
• Damp or musty smell
• White powder on walls (efflorescence)
• Water coming through cracks
• Sump pump failures or backups
• Mold or mildew growth
• Drop in indoor air quality
• Wall discoloration
• Peeling paint or bubbling drywall
• Bowing or shifting foundation walls

Even small issues can become expensive if ignored, especially on older Main Line properties.

 

Why Homeowners on the Main Line Trust Us

For more than 35 years, Main Line Waterproofing has been the local choice for reliable basement waterproofing solutions. Homeowners choose us because:

• We’re honest. We recommend the right fix — not the biggest one.
• We understand local foundations. Stone, block, poured concrete, stacked stone — we know how each one behaves.
• We know the Main Line water table better than anyone. From Ardmore to Devon, we’ve worked in nearly every neighborhood.
• We respect your home. Clean work, professional crews, and clear communication.
• We deliver long-term results.

Our approach is rooted in trust, transparency, and real expertise — the same values that keep homeowners referring us to neighbors, friends, and contractors year after year.

 

Get Your Free On-Site Assessment

Basement waterproofing is not one-size-fits-all. The right solution depends on your foundation, soil, drainage, and the unique way your property handles water.

Whether you’re in Bryn Mawr, Wayne, Villanova, Ardmore, Haverford, Gladwyne, or anywhere else along the Main Line, we’re here to help you understand your options and protect your home.

Contact Main Line Waterproofing today to schedule your free assessment and keep your basement dry for good.