Is It Better to Repair Basement Leaks Inside or Outside?

Should you repair basement leaks from the inside or the outside?

At Basement Masters Waterproofing one of the most common questions our Northern Virginia and Southern Maryland homeowners ask is, “Is it better to repair basement leaks from the inside or the outside?” One of the reasons they ask is because the advice from the internet often differs from that of basement waterproofing professionals.

With most topics you look into, you will find answers on both extremes that sound authoritative and may even be backed by “research”. It is important to know the facts, however, and sometimes very few sources come easy to find for getting to the bottom of questions like these. This article was written to provide the answer you can count on to keep your home in shape and help offer some protection from further damage.

How Water Enters A Basement or Crawlspace

Leaks in the basement can come from several different sources. Indoor humidity can cause the water to seep into the basement, while outdoor sources can saturate the soil surrounding the foundation. Leaks can also occur from plastic piping or cracks in the foundation.

If you find that water is dripping through the walls, you can use hydraulic cement to plug the holes. However, this method is only temporary. Moreover, hydraulic cement only fixes small holes or cracks. Hence, it isn’t ideal for a large amount of water and does not offer a permanent fix.

Interior Repairs Vs Exterior Repairs

Most basement leak repairs, regardless of whether they are performed on brick, cement block, or concrete foundations, can be performed from the inside or the outside of the home. If you have a poured concrete foundation, both interior and exterior waterproofing repairs can be effective in preventing a wet basement. Exterior leak repair can be more desirable and less costly under a limited number of following circumstances:

• The cost and time of removing and replacing interior walls and furnishings, such as wood paneling and built-in bookcases or a brick fireplace are prohibitive.
• Excavation work is required anyway to repair a bowed wall, add or repair external drainage systems, or correct composition, voids, or grading with the soil surrounding the foundation.

However, in the majority of cases, interior waterproofing is more effective and efficient than doing exterior excavation, wall repair, and replacement of soil, utility lines, drainage systems, decks, and landscaping.

Why Interior Repair is Usually a Better Approach

Wet basements can be caused by a number of problems. From our experience, the best approach to a leaky basement comes from the inside.

It takes less time

It takes a great deal of time and effort to remove and replace the soil, exterior drainage systems, decks, fences, landscaping, and utility lines outside of foundation walls. There is also an increased risk of damaging tiles, utility lines, root systems, requiring additional time to repair them.

It is less expensive

Injecting into an interior crack may cost several hundreds of dollars, but removing and replacing soil and landscaping may cost several thousand. Also, there is less risk of additional costs for repairing and replacing damaged tiles, utilities, fences, decks, and landscaping.

It can be done during any weather

Exterior work cannot be done when the ground is frozen or wet. Also, it requires an entire crew to be scheduled during dry weather. Work on other projects may delay their ability to work on yours. An interior crack injection can be performed during any weather and requires only one person.

It detects the source of the leak

If the problem isn’t visible on the inside walls, you can’t be certain of the source of the water. From the outside, there could be any number of rod holes leaking. The only way to know the exact source of the leak is to observe the entire interior wall from the inside.

It repairs voids in the wall

Injecting a polymer into cracks in foundation walls actually fills the voids all the way through the wall while exterior repair only patches the outside.

It lasts longer than concrete patches

Concrete patches will eventually crack and leak due to the same conditions in the soil that caused the leak in the foundation in the first place. Polymers are waterproof and expand and contract during changes in temperature.

It is less dangerous

Anytime crews dig a hole on the outside of a foundation wall, there is always an increased risk that the soil will cave in or there may be another type of mishap on the excavation site.

Quality of the Repair Depends on the Person Doing It

From a warranty standpoint, whether the leak repair is done from the inside or outside doesn’t matter. Both methods are commonplace in the industry, and if exterior repairs weren’t effective, those contractors would be out of business.  Like anything else, the quality of the work is the best determinant of the success of a repair.

What is most important is the skill and attitude of the waterproofing professional working on your basement leak. They must be able to make an accurate diagnosis of the problem and repair the leak without taking any shortcuts. The reputation of the contractor and personal testimonials are often the best way to judge who will do the best job of fixing your basement leak. (Not what one blogger is paid to say or another fly-by-night company is trying to sell you on!)