A concrete foundation can fail for several reasons. Before we delve into whether you should repair foundation cracks from the inside or the outside, a quick word of caution–if a foundation crack repair is required, contact Crackmaters Basement Waterproofing Specialists rather than a handyperson or plumber. Saving a few dollars at the expense of structural integrity can be a costly mistake.

When executed correctly, sealing foundation cracks, either from the inside or the outside, are equally effective. If a deck or patio is in the way or the basement is unfinished, it would be best to seal cracks from the inside. The use of an external technique is recommended when there is drywall, paneling, or a furnace in the interior.

If you’re unsure how to approach foundation cracks, leave the decision to the person repairing it. The crack location, type of crack, depth of the damage, and various other factors will influence this decision. You should make the final call only after a proper on-site examination by a specialist.

Foundation Crack Repair From the Interior

Foundation Crack Repair from the Interior

In the past, sealing a crack meant “chipping it out and patching it.” Concrete was removed with a rotary chipping hammer, and hydraulic cement was applied. While these types of repairs were quick, they were not long-lasting. Since the fissure was not completely filled, it wasn’t solid. Furthermore, the hydraulic cement used for the task was not durable or strong. Epoxy resins were also popular in the past, but today they are viewed as more appropriate for structural problems.

The most common method of internal foundation crack repair is a crack injection –either with epoxy or urethane. Epoxy injection seals the fracture’s interior face with epoxy paste and uses a resin (epoxy or urethane) to fill the crack inside out. According to most experts, urethanes are more effective for waterproofing because they retain flexibility.

Interior Foundation Crack Repair

When Interior Crack Repair is Preferred

If the crack is causing a damp basement, you’ll find specialists recommending that repair be done from the inside. There are quite a few reasons for this.

  • An internal repair can help pinpoint the issue. Any number of rod holes may be leaking from the outside. The only way to determine the precise cause of the leak is to examine the whole inner wall from the inside.
  • Patching from the inside enables you to inject a polymer into the foundation wall fissure, which would fill the gaps all the way through. External restoration would only repair from the outside.
  • Restoring from the inside is not as cumbersome as exterior repairs requiring you to remove and replace the soil and take care of external drainage systems, decks, fences, landscaping, and utility lines. There is also a greater chance of damaging tiles, utility lines, and root systems.
  • Internal repairs are more cost-effective. Injecting into an internal fracture may cost a few hundred dollars, but the removal and replacement of soil and landscaping would cost several thousand. You also minimise extra expenses for repairing and replacing broken tiles, utilities, fences, decks, and landscaping.
  • Internal crack repairs can be done in any climate and only needs one person. In contrast, outside work must be planned during dry weather.
  • Typically, exterior repairs utilise concrete patches which may fracture and leak. Inner polymers, on the other hand, are waterproof. They will expand and compress with temperature changes without affecting the structure’s integrity.
  • Internal repairs are also safer. Whenever workers excavate a hole outside a foundation wall, there is a greater chance that the earth will cave in or cause another accident at the excavation site.

Foundation Crack Repair From the Exterior

It’s essential to watch out for foundation cracks, especially external fractures that increase the likelihood of water penetration and other difficulties. Walls and ceilings may have gaps, but foundation cracks are just as important to watch out for. Inside cracks are commonly produced by ground movement or concrete faults, whereas outer cracks are caused by weathering. Homes and dwellings are susceptible to this damage when the temperature changes throughout the year.

Many homeowners feel that the best approach for foundation crack repair is from the outside. The specialist may try removing a small section of the exterior foundation to check if the whole wall is damaged or simply the plaster. To seal a breach from the outside, excavate from the top of the wall to the footing. Fill it with granular clay to create an impenetrable water barrier.

Because outside fractures may be the consequence of inner fissures, you should thoroughly investigate the inside of your foundations. Specialists tailor their repair procedures to the kind of crack; therefore, you must perform thorough inspections before deciding on the best course of action.

Repair Foundation Cracks From Exterior

When Exterior Crack Repair is Preferred

Exterior repair may be more desirable and less expensive in a few of the following instances:

  • Cost and time are prohibitive for removing and replacing interior walls and fixtures, such as wood paneling, built-in bookshelves, or a brick fireplace.
  • Repairing a bent wall, adding or repairing exterior drainage systems, or correcting the composition, voids, or grading of the soil around the foundation all need excavation, which is best done from the outside.
  • Since a portion of your foundation is subterranean, the experts may need to use a mini-excavator to excavate the work area and access the issue region. In such a case, it makes sense to do the repairs from the outside.
  • Repairing foundation cracks begin with cleaning and opening the crack to create a V, followed by applying quick-setting cement and sealing with a high-performance polymer-based sealer. It must possess sufficient flexibility to withstand ground movement.

The Final Decision

Both interior and external crack repair alternatives are possible, and the final decision depends on the obstacles and specific circumstances. From a warranty viewpoint, it makes no difference whether the foundation crack repair is performed from the inside or outside.


At Crackmasters, our team has over 20+ years of professional experience with cutting-edge basement waterproofing, basement crack repair, and foundation crack repair systems. A lifetime guarantee backs our foundation repair services. For a free estimate and inspection, contact us today.

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