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Are My Basement Wall Cracks Normal or Dangerous?

If you notice any type of crack on your basement wall, stick around. This article is perfect for homeowners in New Jersey who want to know the difference between “normal” basement wall cracks that don’t require immediate attention and dangerous cracks that can threaten your home’s structural integrity. You’ll also learn about the different types of basement wall cracks, five easy ways to evaluate their severity, and cost-effective ways to repair them.

What Basement Wall Cracks Are “Normal?”

Normal basement wall cracks do not immediately threaten your foundation or home’s structural integrity, but they can allow water seepage and should be monitored for any signs of growth. “Normal,” non-structural cracks are:

  • Less than 1/8th of an inch wide (about the same width as a US nickel). 
  • Isolated to a single part of your basement wall, such as a single concrete block. 
  • Stable (do grow or widen).
  • Near typical stress points of your basement (windows, I-beams, corners, floors, longer wall sections). 

“No cracks on your basement wall are considered “normal” by experts. All cracks are an indication of an underlying foundation problem that occurred before, during, or after it was built. Some cracks can occur because of improperly mixed concrete, while others occur because the soil around your foundation wasn’t graded properly and water built up against your basement walls during rainier seasons.”

-Steve Karlik, Owner & Founder of Blue Umbrella Waterproofing

Types Of Normal Basement Wall Cracks

Here are three common types of basement wall cracks that don’t require immediate attention but can worsen over time.

Hairline Cracks

Hairline cracks, also known as shrinkage, cosmetic, and “spiderweb” cracks, usually occur due to concrete’s natural curing (drying) and shrinking process. Hairline cracks can also occur during small amounts of settlement after your home is newly built. This settlement happens as your foundation settles evenly into the soil below it, a process known as uniform settlement. Hairline cracks can occur in both block and poured basement walls.

Vertical Cracks

Vertical cracks are considered “normal” because they’re not as severe as other wall cracks. These are commonly found on poured walls because cracks seek out the path of least resistance (the height of your basement wall is shorter than its width). However, look out for multiple vertical cracks running parallel to each other, cracks that are growing, or cracks that allow water seepage. Vertical cracks continuing into the floor are also concerning and likely involve your basement footers.

Diagonal Cracks

Here are two concerning basement wall cracks that require urgent attention. If you notice any of these cracks on your basement wall, contact a professional foundation repair company immediately. 

Thin, diagonal cracks near window or door frames running at a 30 to 75-degree angle are usually caused by concrete shrinkage and aren’t an immediate emergency. These cracks are usually wider at one end than the other. Diagonal cracks can worsen if they’re initially caused by differential (uneven) foundation settlement. The tension caused by one side of the foundation sinking lower than another throws your house out of alignment, leading to cracks in materials that aren’t designed to bend (concrete, wood, drywall).

Blue Umbrella repairing a damaged foundation in a New Jersey home

What Basement Wall Cracks Are Dangerous?

Horizontal Cracks

Horizontal cracks are typically caused by external pressure pushing against poured block walls also called cinder blocks or CMU concrete masonry, units, and brick foundations. External pressure can be caused by hydrostatic pressure (moisture/water buildup in the soil), frost heaving (frozen moisture/water in the soil), and excessive backfilling (builders placed too much dirt around your basement wall). Horizontal cracks in your basement wall can grow larger and allow more water leakage as the pressure outside expands and contracts, causing the wall to bow, tip, and shear. 

Stair-Step Cracks

Stair-step cracks are caused by differential settlement and typically run from the bottom corners to the middle of block basement walls and brick fascias. Stair-step cracks directly damage the mortar joints holding blocks and bricks together, allowing them to shift and widen, which can eventually lead to the separation of wall pieces and structural collapse.

5 Ways To Evaluate Basement Wall Cracks

This list can help you determine how you should address a crack in your foundation based on its characteristics.

  1. Location: Some cracks can be above ground level and may not be leaking water, while others can be closer to your cove joint (the space where your basement floor and wall meet), allowing excessive amounts of groundwater to leak through. 
  2. Size: The National Association of Home Builders (NAHB) states that all foundation wall cracks exceeding 1/4-inch wide should be repaired, but most foundation repair experts recommend catching them before they exceed 1/8-inch wide. 
  3. Leaking: Look for visible water stains on your wall after it rains heavier than usual. If your basement is finished, you might need to remove a section of drywall to find a leaking crack. In some cases, you may be able to smell moisture or odor leaking through the crack.   
  4. Growth: Outline the crack using a marker or pencil, and use a ruler or tape measure to measure the width, length, and depth of the crack. Check the crack at least every few months or after extreme weather, and compare your earlier measurements. If you don’t feel comfortable waiting for a crack to grow, a foundation repair inspection can help you identify if a crack is dangerous.
  5. Frequency: If a crack reappears after it’s been repaired or patched, chances are the issue isn’t concrete shrinkage and likely originates from differential settlement, hydrostatic pressure, or another structural issue.
New Jersey Damaged Foundation Wall

How To Repair Basement Wall Cracks

Foundation repair experts choose crack repair solutions based on their severity and cause, as the wrong method could overcorrect the damage, cost more than necessary, or fail to address the root issue, leading to further repairs in the future.

Non-Structural Crack Repair

Normal cracks that don’t threaten your home’s structure can be filled and patched to prevent leaks and improve its appearance (which can affect your home’s value). Foundation repair experts clean the area, create a small groove alongside the crack, and fill it with a hydraulic cement mixture. After the cement dries, the crack is covered with a commercial-grade epoxy and rubber coating that bonds with the cement, creating an impenetrable seal.

Structural Crack Repair

Structural cracks in New Jersey are typically repaired using carbon fiber straps or steel I-beams. Both solutions only take one to two days to complete.

Carbon Fiber Straps

Carbon fiber straps (strips) are tougher than steel and are used to correct basement walls that have bowed or leaned inward less than 2 inches. These non-invasive straps are anchored, tightened, and bonded against basement walls, preventing the wall from shifting or cracking any further. 

Carbon Fiber Strap Installation in New Jersey

Steel I-Beams

Steel I-beams are perfect for cracked basement walls that have bowed inward more than 2 inches. Similar to carbon fiber straps, these beams are sized, cut, and installed directly on your basement wall with anchors at the top and bottom.

New Jersey Steel I-Beam Installation Foundation Repair

How Much Does It Cost To Fix Basement Wall Cracks?

The cost of basement wall crack repair depends on the type and source of the crack. Repairing a hairline crack using an epoxy or hydraulic cement mix can start around $1000. Repairing larger structural cracks can start around $1800 to $2400 depending on the method used. However, the cost of these solutions are nothing compared to the effects of a collapsing basement wall. 

Unaddressed cracks can lead to damaged flooring, split floor joists, cracked or moldy drywall, broken water pipes, broken electrical wires, and tens of thousands of dollars in structural repairs. Experts agree it’s much safer and financially smarter for homeowners to address basement wall cracks before they get to this level.

Worried About Basement Wall Cracks – Call Blue Umbrella!

If you notice a crack on your basement wall in New Jersey, contact Blue Umbrella Waterproofing today. We bring more than 20 years of experience to every basement repair project, whether it’s dealing with cracks, bowing walls, or water seepage. We offer free estimates to all customers and are fully licensed and insured in New Jersey. Call, or sign up for a free estimate to get started.

Steve Karlik

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