Comparing interior and exterior basement waterproofing

Last month (who else can’t believe we’re already almost halfway through August?) I shared some of the water leaks we’ve had in the basement. Starting today, I’m going to go into a bit more detail about the waterproofing process.

Up first, I’m going to talk about the different waterproofing options we considered and what we ended up choosing.

Option 1: Exterior Waterproofing

Waterproofing a basement foundation from the outside

I don’t have any experience with waterproofing, but exterior waterproofing is what I was at least passingly familiar with.

In this approach, the foundation is dug out from the outside. You dig down the full depth of the wall all the way to the footing. Then weeping tile (that black corrugated flexible pipe) is laid in the trench along the base of the foundation. The idea is that water flows into the the weeping tile and is funneled around the foundation and into a sump pit.

The foundation wall is coated with sealant and/or membrane. And then the dirt is backfilled.

Option 2: Interior Waterproofing

Waterproofing a basement foundation from the inside

Due to my inexperience with waterproofing, the first time a contractor suggested an interior approach my reaction was, “But don’t I want the water to stay outside?”

It turns out, you can’t always keep the water out. But you can manage it once it gets in.

The method for interior waterproofing is somewhat similar to exterior, except for the digging. In interior waterproofing, the concrete floor is cut along the perimeter of the wall. The concrete is removed and then the dirt is excavated down to the footing. Weeping tile is laid along the footing and is funneled around the wall and into a sump pit.

The trench is filled with gravel and the floor is repaired with new concrete.

Option 3: Interior Waterproofing 2.0

As we went through the meetings with various waterproofing contractors, we came across one that had a slightly different approach. They worked from the inside like the other contractor had recommended, but the materials that they used were a bit different. The conduit that they laid along the footing were guaranteed never to become clogged with silt. They had membranes for the walls that funneled any seepage or humidity into the pipe. They had all kinds of informational videos and patents on a lot of their materials.

Their sales pitch was that they had invented a better mousetrap waterproofing technique. And they would guarantee it for forever.

Basement waterproofing cartoon

Our decision

The first time a contractor mentioned interior waterproofing to me, I admit that my reaction was something along the lines of, “Uh. No way, Jose. Do you see this finished basement? Do you know how much work we put into this? I’m not ripping it up to waterproof from the inside.”

After I calmed down, here were some of the other considerations we weighed in making our decision.

  1. Given the damage we’d had to the drywall, studs and baseboard, I was going to have to do some repairs inside. Waterproofing from the interior would allow us to have one disaster zone inside, rather than two, inside and out.
  2. The two contractors that recommended the interior approach also recommended focusing just on where we had problems, not on the whole foundation. Again, my reaction was a bit skeptical, as I wanted to waterproof only once and make sure we never have a problem anywhere ever. However, no one could guarantee that except for company #3.
  3. Over time regular weeping tile, whether inside or out, can get clogged with dirt. It may take a couple of decades, but when that happens water may once again seep into the basement (see no guarantee above).
  4. In exterior waterproofing, after backfilling the dirt will eventually settle. So a year or two after waterproofing we might have to do more work in terms of adding dirt and regrading.
  5. If we worked from the outside, the whole perimeter of our house would be dug up. I didn’t love the idea of sacrificing all of our flowerbeds after I’ve spent so much effort establishing them (although it did give me an excuse to skip weeding this spring). On the flip side, I liked that the disruption would be confined to the exterior, rather than our finished basement.
  6. All of the methods were within roughly the same price range. Money was not going to be the determining factor.
  7. Company #3 offered a lifetime guarantee that we would have no leaks in the areas that they waterproofed. Options #1 and #2 would only give us a 20 year warranty, but I wasn’t sure that was quite enough for me.

We decided to go with Option #3, Omni Basement Systems.

Omni basement systems truck

Coming up, I’ll talk about the waterproofing process and then share the results.

I’d love to hear your input. Have you ever gone through a waterproofing project? What option did you choose? If you haven’t gone through waterproofing, what solution would you select?

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4 thoughts on “Comparing interior and exterior basement waterproofing

  1. I just sent this post to my landlord. He needs to get cracking on picking a method before the rainy season is here again!
    Have they started your work yet? Your choice of method makes a lot of sense. Question: do you think home insurance might cover the cost? (I can’t remember if you mentioned that in your previous post.)

  2. My last house was built in 1927, and had a full basement. It had a small “trench” (only about an inch deep) in the concrete just inside all exterior walls. All of the trenches were sloped to the corner that had the sump pump. So although water easily seeped through the exterior walls, the trenches contained the water and directed it in the right direction. The premise was good, it’s just that you could never have a finished basement because it was always damp. I never even priced waterproofing because I knew it was way out of my budget and I didn’t actually need the extra space.

    I don’t know what I would have chosen in your situation. I am with you on the thought that I would prefer to waterproof the exterior and keep the water out. But the lifetime guarantee would have been enticing!

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