Is Hydrostatic Pressure The Reason You Have a Wet Basement?

Is hydrostatic pressure the reason you have a wet basement?
Is hydrostatic pressure the reason you have a wet basement?

Hydrostatic pressure could be the reason you have a wet basement. Hydrostatic pressure builds up because of poor drainage in the soil around your home’s foundation. Hydrostatic pressure pushes against your foundation wall and if it isn’t relieved, water will eventually get inside. Hydrostatic pressure can even cause a foundation wall to bow inward and crack—more on this below.

So, if you want a dry basement, good drainage in the soil around your foundation is critical. If there’s good drainage, hydrostatic pressure can’t build up. This is why today, most municipalities stipulate that all new homes must have a drain tile system. 

Hydrostatic pressure and how it affects your basement walls

Hydrostatic pressure builds up when water in the soil around your foundation can’t drain off. The pressure pushes against foundation walls, and if it’s not relieved, water will eventually find a way into your basement, often through tiny, invisible cracks. Hydrostatic pressure can also push water up through the cove joint, where the wall meets the floor. Hydrostatic pressure exerted against a foundation wall is strong enough to cause the wall to bow inward and even crack.
 
Just putting up a waterproofing membrane as a barrier is not enough. It will hold for a while, but eventually, it will fail, and the water will return to your basement. This is because a barrier waterproofing method doesn’t solve the root problem: excess water in the soil outside the foundation wall. Instead of fighting a losing battle against hydrostatic pressure, you need to prevent it from building up in the first place.

A drain tile system prevents hydrostatic pressure from building up outside your basement walls

When it comes to basement waterproofing, a drain tile system is the way to go because it makes sure there’s no excess water in the soil around your foundation. Without the water, hydrostatic pressure can’t build up.

For more information about drain tile systems, see How Does A Drain Tile System Work?

There are two types of drain tile systems, exterior, and interior. It’s possible to install both. Here’s how they work:

Exterior drain tile system
While installing an exterior drain tile system during the construction of a new home is easy, installing drain tile in an existing house is a lot of work:

  • The first step is excavation down to the footer.
  • A shallow trench is dug around the perimeter of the house and filled with gravel.
  • A perforated pipe is placed in the trench and covered with more gravel.
  • The excavated soil is put back.

Now, any excess water in the soil will flow through the perforated pipe and into the sump pit. Depending on how your yard is graded, the water will be released away from the foundation either via gravity or a sump pump.

Interior drain tile system
An interior drain tile system is installed around the inside perimeter of your basement. It requires using a jackhammer to break up the basement floor, so it too is a major construction project:

  • First, the basement floor is broken up, so a shallow trench can be dug around the inside perimeter of the basement.
  • After the trench is lined with gravel, a perforated pipe is placed in it and then covered with more gravel.
  • Finally, the floor is replaced. Sometimes, if the basement isn’t going to be used as a living area, the trench remains uncovered.

Excess water in the soil under the foundation will be directed to the sump pit and ejected away from the house via the sump pump.

drain tile

Repairing the damage caused by hydrostatic pressure 

If one or more basement walls have already been damaged due to hydrostatic pressure, don’t despair. There are several repair options available for cracked and bowing walls, including,
 
  • Wall plate anchors – Wall plate anchors are great for bowed, cracked foundation walls. The anchor has three main parts: the inside wall plate, the outside anchor, and the high-strength rod that connects the plate and the anchor. When the rod is torqued, the wall gets pulled outward.  
  • Carbon fiber wall straps – Carbon fiber is a very strong, virtually unbreakable fabric material. The straps are attached to the sill plate with a galvanized bracket and then attached to the floor using a carbon fiber pin.   
  • Helical wall anchors (tiebacks) – Helical wall anchors are another way to repair bowing basement walls. They’re drilled through the basement wall from inside. They act like a corkscrew, and as the anchors twist, they pull the wall outward. 
  • Basement I-beam wall support – I-beams straighten block or concrete walls over time. They’re useful for when wall plates can’t be used because of yard restrictions or other obstacles. No excavation required.

Signs of excess moisture in your basement

Just because you don’t see puddles of water in your basement doesn’t mean everything’s OK. Here are a few things to watch out for:

  • Mold – The mold could be anywhere, on the walls, floor, ceiling, or items stored in the basement.
  • Efflorescence – Efflorescence looks white and powdery. It’s caused by mineral rich water migrating to the concrete’s surface.
  • Humidity – If there’s excess water in the soil around the foundation, your basement will feel more humid than the rest of the house.
  • Unpleasant odor – Does your basement smell musty? 

Other ways to keep water away from your foundation

Apart from a drain tile system, there are other things you can do to keep water away from your home’s foundation, including,

  • If necessary, regrade your yard – The yard around your home should slope away from the foundation. If it doesn’t, water will drain toward your foundation.
  • Clean your gutters regularly – Clogged gutters can cause water to spill over the side of your home and into the soil around the foundation.
  • Install downspout extensions – If your downspouts are too short, water gets released next to the foundation. Extensions are inexpensive, easy-to-install, and will carry water away from the foundation before releasing it.
  • Don’t plant water-hungry shrubs or trees near the foundation – When you water them, you’ll be saturating the soil around the foundation.
  • Make sure your pipes aren’t leaking – Leaky pipes increase the amount of water in the soil. You don’t want this.

Hydrostatic pressure around your foundation walls is probably the number one cause of wet basements. Fortunately, you can prevent it from building up by installing a drain tile system.

If you’re in our service area in Nebraska, Iowa, Kansas, and Missouri, contact us today for an estimate.

WRITTEN BY

Dave Epp

Dave is the President at Epp Foundation Repair with over 27 years of experience in the industry. Dave has worked on thousands of foundation, basement, concrete, and crawl space repair projects since 1993. Dave is involved in several civic and church organizations and enjoys coaching youth sports, mainly football, golfing, and elk hunting.

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