Is it better to fix a basement leak from the inside or the outside?

Posted by Luc Gerber on Sat, Apr 18, 2015 @ 11:52 AM

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Is it better to fix a basement leak in a poured concrete foundation from the inside or the outside? is one of the most common questions that homeowners ask. The reason the question is being asked is that, whether you research the subject on the internet or consult waterproofing contractors, a homeowner usually ends up getting conflicting advice.

Almost every basement leak repair, regardless of the foundation type, can be performed from inside the home or from the outside, with excellent results. For a detailed list of the available waterproofing repair options, consult our comprehensive Basement Waterproofing Repair Methods page.

Exterior-foundation-crack-repair.jpg Interior-foundation-crack-repair.jpg
Exterior crack repair excavation in progress Interior foundation crack repair by injection

Assuming that you have a poured concrete foundation, both repair methods can resolve your water infiltration problem, the decision to inject a leak from the inside or excavate from the outside is entirely based on your circumstances. In making this decision we recommend that you consider the following:

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What to consider when deciding to waterproof on the inside or the outside

  1. Injection repairs require top to bottom exposure of the bare wall in the vicinity of the repair. In contrast, external excavation will invariably damage the landscaping in the vicinity of the repair as well as the areas wherever the soil has to be piled and where the excavator and crews will be travelling; additionally, fences and decks may have to be removed and rebuilt, and so on.
  2. An injection from the inside costs $100's whereas an external excavation can easily cost several $1000's (not including the cost of re-landscaping, rebuilding the fence, etc).
  3. Injections, which are always carried out from inside, will fill the crack or hole completely from the inside to the outside. An external crack repair involves patching over the crack on the outside.
  4. The warranty provided for an internal injection is generally longer than a warranty offered for an external excavation.
  5. When excavating, it is possible to damage the weeping tile system such that you end up with greater problems after the repair than you had when you started.
  6. When excavating, there is always the risk of damage to gas lines, hydro lines, etc, even if the locates were done properly (assuming that the contractor has gone to the trouble of obtaining the locates). Compared to injection, there is far greater exposure to significant human error when excavating.
  7. With excavation there is always a risk of the earth caving in; if the proper safety procedures and excavation techniques are not being used, and the person in the pit is killed by a cave-in, you may end up being sued.
  8. The scheduling of excavation work is dependent upon the availability of crews and excavators; delays on other jobs due to rain or equipment maintenance can postpone your scheduled repair by days or weeks. Given that injections are typically completed within a few hours by a single technician with fewer equipment requirements, your wait in the event of a delay will be measured in hours, not days or weeks.
  9. If the cost of accessing the wall from inside is prohibitive, or if you have a custom built bar or shelving you might consider external excavation; however, if the problem has not been ascertained by examining the bare wall from inside, you cannot be 100% sure of what exactly needs to be repaired, if anything at all.
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Exclamation markThe location of the puddle on the floor does not necessarily pinpoint the location of the leak. If the exact location of whatever is leaking is unknown, imagine digging up your foundation in the wrong place to carry out the repair.

Image file for TipBefore you sign a contract for any foundation repair, ensure that the cause of the problem is known with 100% certainty. In general, if you haven't observed the problem on the bare walls from inside the home you can't be absolutely certain as to the source of the water; from the outside, you can't possibly tell whether a crack is leaking or whether there are 1 or 2 or 3 or even 10 rod holes leaking. All too often, homeowners agree to $1000's of foundation excavation and waterproofing which is either done in the wrong location, for the wrong reasons, or to resolve a problem that could have been fixed from the inside for far less money.

Topics: basement leak repair, wet basement repair, foundation leak repair