Quick Guide: Can You Seal a Basement Crack From the Inside?

August 14, 2023

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foundation cracks on a home exterior

Basement cracks are a common issue that can allow water, pests, and conditioned air to breach your home's foundation if left unaddressed. Thankfully, many typical cracks can be repaired successfully from inside the basement using DIY methods.

So, can you seal a basement crack from the inside?  Yes, most common basement cracks can be sealed from the inside using concrete sealants, hydraulic cement, polyurethane foam, or epoxy injection kits.

Effective interior crack sealants are available that fill, bond, and seal cracks to form long-lasting watertight repairs. With proper product selection and application techniques, homeowners can seal common cracks in basement walls and floors to prevent leaks, improve energy efficiency, keep out pests, and restore their basement's interior appearance.

Let's hop into the blog for a closer look at interior basement crack-sealing techniques.

Why Seal Basement Cracks?

Cracks in basement walls and floors are common in many homes. While small cracks may seem harmless, over time, they can lead to larger problems if left unaddressed. Sealing basement cracks is important for several reasons:

  • Prevent water seepage - Cracks provide an entry point for water to seep into your basement. This can lead to flooding, moisture damage, mold growth, and foundation damage over time. Sealing cracks helps keep water out.
  • Improve energy efficiency - Cracks allow conditioned air to escape and unconditioned air to enter your home. Sealing cracks reduces drafts and improves insulation. This can help lower energy bills.
  • Aesthetic reasons - Cracks detract from the appearance of finished basement spaces. Filling cracks provides a more attractive interior.
  • Stop pest entry - Cracks allow easy access for bugs, insects, and rodents to get into your basement. Sealing cracks shut down an entry point for pests.

can you seal a basement crack from the inside

Crack Repair Options

There are several good options for sealing basement cracks from the inside:

Concrete Crack Sealants

Concrete sealants are designed to fill cracks in concrete and masonry. They come in caulking tubes or pourable liquids that can penetrate deep into cracks through gravity or injection. Polyurethane, acrylic, and epoxy-based sealants are common. Sealants bond tightly to the concrete surface once cured.

Hydraulic Cement

Hydraulic cement is a quick-setting compound that can plug leaks and seal cracks. It expands as it sets to form a watertight seal. It comes as a powder that is mixed with water before applying. Hydraulic cement can be useful for stopping active water leaks.

Epoxy Injection Kits

Epoxy injection involves filling cracks with low-viscosity epoxy resin that gets injected under pressure. The epoxy bonds and hardens to form a permanent watertight seal deep inside the crack. Injection kits allow DIY application. Professional services are also available.

Polyurethane Foam

Expanding polyurethane foam makes a great interior crack repair option. The foam can be sprayed or injected into cracks where it expands and hardens. The flexible nature of cured foam allows it to move with any shifting while maintaining a seal. Expanding foam is quick and easy to apply.

DIY Crack Repair Steps

Here is a simple DIY process for sealing basement cracks from the inside:

  • Clean the crack - Use a wire brush and shop vacuum to clean out any dirt, debris, or crumbling material from the crack. This allows the sealant to adhere properly.
  • Prepare the surface - Etching the concrete with a grinder or acid provides a rough surface for maximum adhesion.
  • Apply backer rod - Insert a flexible backer rod into the deeper parts of the crack to provide a backstop for the sealant.
  • Apply sealant - Follow product instructions for applying the concrete sealant, hydraulic cement, expanding foam, or epoxy resin. A caulking gun allows neat application for small cracks. Use injection ports or foam backer rods as needed for deep crack penetration.
  • Smooth/finish sealant - Tool or smooth the sealant with a putty knife or trowel for a clean finished look. Remove any excess.
  • Allow to cure - Read product directions for cure times. Do not disturb the crack repair while curing. Protect from water exposure.
  • Check for leaks - After full cure, examine the crack seal during heavy rain. Watch for any moisture coming through. Reseal if needed.

can you seal a basement crack from the inside

Can You Seal a Basement Crack From the Inside? Tips for Making it Happen

Follow these tips to ensure an effective interior crack repair:

  • Choose the right sealant for the specific crack and application. Consider width, depth, location, and movement.
  • Prepare the crack surface thoroughly for maximum adhesion.
  • Ensure the sealant penetrates fully into the crack rather than just superficial bonding.
  • Apply the sealant neatly according to directions to prevent voids or weak spots.
  • Allow adequate cure time before subjecting the seal to hydrostatic pressure or movement.
  • Monitor the sealed crack and reseal if any leaks develop.

cracked wall foundation

Professional Crack Repair Services

For cracks wider than 1/4 inch, extending around corners, or showing signs of foundation movement, professional services are recommended. Experienced foundation contractors have specialized expertise and equipment to diagnose the true source of cracks and repair them comprehensively.

Common professional methods include:

  • Epoxy injection - Epoxies formulated for foundation repair is injected under high pressure to penetrate deep into fine cracks. Multiple injection ports are strategically placed.
  • Carbon fiber reinforcement - Carbon fiber straps and rods can be installed on basement walls via epoxy adhesives to reinforce cracked areas. This helps stabilize foundation walls.
  • Wall anchors - Steel anchor bolts are driven into the ground around the perimeter and attached to the basement walls with brackets. This provides added structural support.
  • Concrete push piers - Hydraulic jacks are used to push steel or concrete piers against the foundation wall footing to counteract inward movement.

In more extreme cases of foundation damage, underpinning repairs may be recommended to stabilize sinking foundation walls. Professional installation of an interior drainage system or exterior waterproofing can also manage leakage issues. Addressing severe cracking proactively prevents further structural damage.

foundation repair company contractors in Grand Rapids

About Grand Rapids Foundation Repair Pros

For over 20 years, Grand Rapids Foundation Repair Pros have been keeping residential and commercial properties standing on solid ground. The company offers professional foundation services that are affordable and long-lasting. Please contact us by calling (616) 952-2799, and our team will connect you with a zero-cost inspection and quote.


How do you fix a crack in the inside of a basement block wall?

First, clean out the crack thoroughly using a wire brush and shop vacuum to remove any dirt, debris, or loose material. Then, fill and seal the crack with a concrete sealant, hydraulic cement, expanding polyurethane foam, or epoxy resin injected into the crack according to the product's instructions.

Is it better to fix foundation crack from inside or outside?

For minor cracks, it is often easier and less expensive to do crack repairs from inside the basement using DIY methods with concrete sealants or expanding foam. For major foundation cracks, extensive leaks, or signs of shifting, it is better to hire a foundation repair contractor to permanently fix the issue from the outside by sealing foundation walls with injected epoxy, concrete patching, steel supports, or hydraulically driven wall braces.

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