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Why Does Water Intrude At The Top Of My Foundation?

water dripping down basement wall
Generally, if you have water in your basement or crawl space, it’s because water has seeped through the wall, entered through cracks, or oozed in through the cove joint (where the floor and wall connect).   But every once in a while, you may have water coming into your home from the top of the wall.

Acculevel specializes in waterproofing and foundation repair.  Since Andy Beery founded our company in 1996, we’ve helped more than 35,000 homeowners preserve and protect their homes.  We want to help you do the same- even if our services aren’t the right fit for you at the moment.

We’re going to explain how water can intrude into your home from the top of the foundation, and how this kind of leak should be addressed.  This is not a common problem, but if it’s happening to your home?  It’s a serious issue you need to address promptly.  


How Can Water Enter At The Top of Your Foundation? 

Before we can explain how water is getting through this unusual entry point, we need to explain where the entry point is. 

Construction Basics

Bear with me, because we’re starting out with the obvious.  When your home was built, the foundation was the first part completed.  Once your foundation was established, the wooden flooring structure was built on top of it.  

In the diagram below, you can see the sill plate was then attached directly to the top of the foundation wall.  A band joist, also known as a band board, was attached to the outside to protect the ends of the beam and joists.

Illustration of structural wood framing
This illustration of a flooring structure is courtesy of NCSU.


The main beam is placed down the center of the home, with the ends resting on the sill plate.  Floor joists then span the house, perpendicular to the beam.  The ends of the floor joists also rest on the sill plate.

The band joist and sill plate are normally covered by siding, brick facade, or similar exterior coverage.  This layer protects everything above the foundation from rain, snow, wind, etc. 

water stain at top of basement wall
This photo was taken by an Acculevel project advisor during a routine free home assessment.  Water is seeping in over the sill plate.


The Top Of Your Foundation Should Be Protected

In the photo above, you can see water coming in at the top of the wall, then running down the inside of the basement.  This wouldn’t happen if the wooden structure at the top of your foundation was properly sealed.

Water is able to leak into your home above the foundation line when it can penetrate the protective layer on the exterior of your home.  It doesn’t matter if you have siding, stucco, or a brick facade; any type of covering can develop a leak.  

It doesn’t have to be a defective component, either.  All you need is a crack in the product, a faulty seal between the facade and the home, or a compromised seam.  After all, these protective layer products have to have seams somewhere, as they encircle your home, right? When a break in the seal or gap in coverage develops, water will find its way through it.

water dripping down basement wall
This photo was also taken by an Acculevel project advisor during a free home assessment.  You can see water is seeping in and down the basement wall.


How Do You Stop Water Intrusion Above Your Foundation?

The critical first step is identifying where the leak originates.  Who you hire to make repairs will depend on the exterior of your home and the location of the leak.

  • Brick or stone facade: you will need to contact a masonry company to repair damaged or decaying mortar.  
  • Siding: a general contractor can remove the siding, make repairs to any damaged seams, and replace or re-install the siding.  
  • Landscaping: if plants or excess mulch have blocked necessary drainage at the foundation, you may need a professional to reestablish the proper grading around your home. 

You may need more than one of these contractors, if water has damaged more than just the edges of your home. Once the exterior coverage is removed to expose the framework behind it, you may find additional problems.  Long-term exposure to moisture can produce mold, decaying lumber, or pest intrusions. 


Can Waterproofing Solve This Problem? 

Basement waterproofing will not stop water intrusion above the foundation. We are experts in waterproofing basements and crawl spaces, but our methods and products are designed to address water that enters your home through the walls and/or floor.   None of Acculevel’s methods for waterproofing are designed to work at the top of a wall. 

But we’ve been helping homeowners protect and preserve their homes for decades.  We know how badly water can damage your foundation, and it can be just as devastating to your home above the foundation.  It is critical that you find the source of the water leak, and prevent mold and decay from developing inside your home’s walls. 


Acculevel Has Resources For You

We may not be able to help you with all of your home repair needs, but we want to make sure you find the best contractor for your particular situation.

Once you’ve repaired the leak in your home’s exterior, make sure you take steps to prevent new issues from developing.  Use our DIY Home Inspection Checklist to make sure your home stays healthy and strong for years to come!



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