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Why Are Weep Holes Important for Basement Waterproofing?

Time to Relieve That Pressure

Do you remember learning about dams in science class? These barriers are used to retain water and provide more control over a water supply.

Wet basements are similar to dams…with one major difference. While dams are designed to release water on demand, basements don’t have this luxury. When water infiltrates the foundation, it will continue to rise and exert pressure on the walls, which can result in a leaky basement, structural damage and more.

This is when weep holes make all the difference. By drilling weep holes into the foundation, we’re able to reduce hydrostatic pressure and remove water from within the walls.

At Blue Umbrella Waterproofing, we’ve seen the amount of water that can drain from weep holes. That’s why our basement waterproofing company in Bergen County, NJ, drills weep holes into every interior waterproofing system. It’s a simple but crucial step to alleviate that pressure and keep your home as dry as possible.

Blue Umbrella Waterproofing on the job in Union, NJ drilling weep holes.

What is Hydrostatic Pressure

Hydrostatic pressure is created by a fluid trying to reach equilibrium while under the force of gravity. That’s the science class definition.

In simpler terms, it’s the pressure that builds as water fills in the soil surrounding your basement and pushes against your basement wall.  

The more water in the soil, the more pressure on your home’s foundation. Given enough pressure, water will seep through your basement walls into your basement. On top of that, the immense pressure can cause structural damage to your basement walls (bowing, tipping, and shearing).

You need to relieve that pressure. That’s where weep holes come in.

When Are Weep Holes Beneficial?

If your foundation is made of concrete masonry units (otherwise known as CMU blocks, cinder blocks or concrete blocks), that’s when you’ll want to have weep holes in your waterproofing system.

Even though CMU blocks form a strong structure when placed together, each individual block contains hollow cells. As water leaks into the wall, it enters these hollow cavities and increases hydrostatic pressure. All this pressure can eventually cause water to leak into your basement and damage your foundation.

While hydrostatic pressure can’t be eliminated completely, it can be controlled thanks to weep holes. These holes effectively drain water from the CMU blocks to put less pressure on your walls and your foundation. Once the holes are drilled, water will then drain into the French drain system. From there, the water will travel through the system and into the sump pump pit where it will be discharged away from your home.

To summarize, weep holes are beneficial if:

  • Your foundation is made of CMU blocks.
  • Your basement frequently leaks.
  • You’re about to finish your basement.
  • You’re having a French drain installed in your basement.

How Does Blue Umbrella Drill Weep Holes?

It isn’t enough to drill a few weep holes here and there. At Blue Umbrella, we drill holes into every cinder cell and every mortar joint. This ensures that your waterproofing system can remove as much water as possible.

We also drill the lowest course of block. By lowest course, we mean the lowest layer of block in the foundation. The drilling point is about one to two inches above the area where the lowest course of block meets the footing. Sometimes during the drilling, we’ll hit solid concrete in the block. This is because when your home was being built, the mason filled a portion of the lowest course of block with cement. When this is the case, we will raise the drill bit slightly to find an area of the block that is hollow. This ensures that each weep hole will function properly.

Weep holes basement waterproofing nj
Weep holes drilled by Blue Umbrella Waterproofing.

Once the holes are drilled, we flush them out with water to remove any additional debris. We then cover the holes with MiraDRAIN board (otherwise known as PolyDrain board) so the water can flow right into the French drain.

Water Damage Without Weep Holes

Without weep holes to relieve the hydrostatic pressure, water builds up around your foundation, slowly eroding it over time, pulling apart the poured concrete, the mortar between stones, or in the case of the photo below, the block walls. Weep holes allow you to capture water safely in a french drain as part of an interior waterproofing system, avoiding this type of water erosion and damage to your foundation, which, left unchecked, can require foundation repair.

Water damaged basement block wall - foundation damage
Basement Foundation Wall Damaged By Water Erosion

How Does Water Erode My Concrete Foundation?

As outside water seeps into and sits in the concrete of your foundation walls, it can dissolve the sub-materials, like calcium hydroxide, that hold the concrete together. 

Additionally, rust can form if the intruding water comes in contact with trace iron and oxygen, causing expansion. 

The expansion from rust and tiny cavities left behind by dissolved sub-materials weakens the concrete and can cause it to fall apart, compromising your home’s foundation.

Basement Water Problems

As water weakens the concrete of your foundation, the water will continue seeping through till it makes it into your basement. 

Once inside, it can cause a slew of other problems, including rotted wood supports, increased humidity in your home, rusted mechanical equipment like your HVAC system, mold growth, and, of course, basement flooding.

Preventing all of these problems comes back to alleviating the hydrostatic pressure – controlling basement water and moisture, starting with weep holes.

Take Pressure Out of the Equation With Blue Umbrella

Hydrostatic pressure can do a lot of damage over time. But with a solid waterproofing strategy, you can keep your basement dry all year long. Trust the experts at Blue Umbrella to relieve that extra pressure with a French drain installation in Union County, NJ, or elsewhere in our service area. Time to take pressure out of the equation!

To learn more about our waterproofing solutions or to schedule service, contact us online or call Blue Umbrella Waterproofing at 908.432.8858 today.

Steve Karlik

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