Below Grade Waterproofing: What It Is and Why It Could Be Important to You

Most homeowners don’t think twice about what’s happening underneath their house until there’s a problem. Maybe you notice a musty smell in the basement after a heavy rain. Maybe your crawl space feels damp, or you start to see water stains creeping up the walls. These are all red flags that point to one major issue: water is getting where it doesn’t belong.

That’s where below grade waterproofing comes in.

While the term might sound like something pulled from a contractor’s textbook, the truth is, it’s something every homeowner should understand. In fact, below grade waterproofing might be one of the most important steps you can take to protect your home’s foundation, structure, and long-term value.

Let’s break down what it is, why it matters, and what you can do to keep your home safe and dry above and below the surface.

What Does “Below Grade” Mean?

First, let’s clear up the terminology. The word “grade” in construction refers to the ground level around your home. Anything that sits at or above the surface is considered “above grade,” while anything beneath ground level is “below grade.”

That includes:

• Basements

• Crawl spaces

• Foundations

• Underground retaining walls

• Parking garages and cellar-level spaces

These below-grade areas are particularly vulnerable to water intrusion because they’re literally surrounded by soil which can trap and funnel water toward your home, especially during heavy rains or snowmelt.

So, What Is Below Grade Waterproofing?

Below grade waterproofing is a combination of materials, techniques, and systems that work together to keep water from entering below-ground parts of your structure.

It’s not just one product or one method. It’s a comprehensive system designed to block water from penetrating your foundation walls, seeping through cracks, or building up pressure behind basement walls.

Depending on the situation, below grade waterproofing can involve:

• Waterproof membranes applied to exterior foundation walls

• Drainage boards and protection layers

• Exterior footing drains and sump pumps

• Concrete sealers and barrier coatings

• Proper grading and soil backfill around the structure

The goal? To stop water before it ever has the chance to get in.

Why Below Grade Waterproofing Matters

1. Water Is Persistent and Destructive

Water has a way of finding the tiniest vulnerabilities in your home. One hairline crack in your foundation wall? That’s all it takes. Add pressure from surrounding wet soil, and that trickle can turn into a steady seep or even a flood over time.

Once water gets in, it’s not just a nuisance, it can damage insulation, rot wood, encourage mold growth, and even weaken your home’s foundation.

2. Your Basement Is Part of Your Living Space

For many homeowners, the basement isn’t just a dark corner for the furnace anymore. Finished basements are used as family rooms, guest suites, gyms, or home offices. Even if yours isn’t finished, you’re probably storing seasonal decorations, keepsakes, or tools down there.

All of that is at risk when water makes its way inside. Moisture can destroy drywall, carpet, electronics, and furniture not to mention create an environment that’s uncomfortable, unhealthy, and potentially dangerous.

3. It Protects the Health of Your Home

A wet or damp basement isn’t just an inconvenience. It’s about air quality, too. Mold and mildew don’t stay confined to your foundation walls. They release spores into the air that travel throughout the home. Over time, this can affect your family’s respiratory health, especially for those with asthma or allergies.

Waterproofing below grade areas helps maintain a healthier, drier, and more comfortable indoor environment.

How Does Water Get In?

Before you can solve a problem, you have to understand what’s causing it. Water can find its way into your below-grade spaces in several ways:

• Hydrostatic pressure: When the soil around your foundation becomes saturated, it pushes water against the walls with surprising force. Over time, that pressure can cause leaks, cracks, or even bowing.

• Poor grading: If your yard slopes toward your home instead of away from it, surface water naturally drains toward the foundation.

• Clogged or absent footing drains: These are pipes installed at the base of your foundation to collect and redirect groundwater. If they’re missing or no longer functioning, you’re more likely to see water pooling around your basement.

• Cracks or porous materials: Concrete and masonry are tough but they’re not waterproof by nature. Over time, small cracks or gaps can allow moisture to seep through.

• Failed waterproofing membranes: If your home had waterproofing applied years ago, those systems may be breaking down or were improperly installed.

When Is the Right Time to Waterproof Below Grade?

Ideally, below grade waterproofing is handled during construction, when foundation walls are exposed and easy to access. But the reality is, many homes, especially older ones, were never properly waterproofed in the first place.

So, the best time to waterproof is before you have a serious water problem. Look out for signs like:

• Musty smells in the basement or crawl space

• Water stains on walls or floors

• Damp or peeling paint

• Mold growth in corners or near the base of walls

• Efflorescence (a white powdery substance on masonry walls)

• High humidity or condensation on basement windows

These are all signs that water is getting in and it’s time to bring in a professional.

The Difference Between Waterproofing and Damp Proofing

It’s worth pointing out that not all moisture-control systems are created equal. Damp proofing is a common method used in older home construction that involves coating the outside of the foundation with a tar-like substance.

While this may reduce the movement of moisture, it’s not enough to prevent actual water penetration or withstand hydrostatic pressure.

True waterproofing is more comprehensive and involves multiple layers of protection:

• A waterproof membrane or barrier that resists water

• A drainage system to move water away from the home

• Protective boards to shield the membrane from backfill damage

Don’t settle for a “good enough” fix. If you’re going to invest in protection, make sure it’s the real deal.

Why You Need a Professional for Below Grade Waterproofing

This isn’t a DIY weekend project. Proper below grade waterproofing requires:

• Knowledge of local soil types and water tables

• Precision when applying membranes and installing drains

• The right materials for the job (cheap alternatives often fail)

• Understanding how to integrate the waterproofing into the landscaping, grading, and hardscape

A drainage and waterproofing professional can:

• Assess your specific situation

• Recommend the right system for your foundation type

• Handle excavation and backfill safely

• Ensure long-term results without cutting corners

In other words: don’t take chances with something as important as your home’s foundation.

Integrating Waterproofing With Landscaping

Believe it or not, the look and function of your yard play a huge role in below grade waterproofing.

A professional drainage and landscaping company can design a full system that includes:

• Proper yard grading to move water away from the house

• French drains or channel drains to catch runoff

• Retaining walls that incorporate weep holes and drainage pipes

• Decorative elements like dry creek beds or rain gardens that absorb excess water

This way, your yard stays beautiful and dry above and below the surface.

Final Thoughts: Don’t Wait Until It’s Too Late

Below grade waterproofing isn’t just something for new homes or high-end construction. It’s one of the smartest, most protective investments you can make in your property.

If you’ve noticed moisture issues, or if you’re renovating your basement or planning new landscaping, this is the time to address it. A dry foundation means a healthy home, a comfortable living space, and peace of mind rain or shine.

Need help diagnosing a water issue or planning a waterproofing system? Reach out to our team today. We’ll walk your property, explain your options, and get to work protecting your most important investment.