How can I effectively waterproof my basement walls to prevent moisture from seeping through during rainy weather and avoid flooding issues?
Asked by Jake Edwards 
5 months ago
Last Updated: July 26, 2024
How can I best waterproof my basement walls? I’ve noticed some moisture seeping in through the stone foundation when it’s raining, but luckily it never floods.
For waterproofing to be effective, it must be done on the outside of the structure. Applying waterproofing on the inside will only lead to water finding another way in, leaving you dealing with it for a long time.
You won’t be able to completely prevent water from coming in. External waterproofing involves digging around your home or setting up a french drain leading to a sump pump to remove any incoming water. I recently had this done, and it has helped me during at least three different storms with water infiltration.
Hey Joe, just a heads up to watch out for those sumps. They tend to be the most common things to fail, I’m telling you. We deal with a lot of floods because of them.
I ended up getting two of them haha. One to use as a backup and another for emergencies if the power goes out. My house is nearly 90 years old so I know the foundation might cause some issues.
No matter what you try, you won’t be able to prevent it. The best solution is to excavate around the house and waterproof from the exterior. It can be quite costly.
I was checking this out the other day. Trying to seal the walls is only a temporary solution. #1 Fix any issues with water getting in, such as faulty eaves troughs, downspouts draining too close, or the ground sloping towards the house. #2 Check if your weeping tile is functioning properly. #3 Do you have a sump pump? If other solutions fail, you may need to install weeping tile from the inside. This video provides a detailed explanation of what needs to be done. It’s not a budget-friendly option, but it will resolve the issue.
Make sure to tuckpoint or parge the rock at the very least. Take care of small sections at a time. Remove the old mortar and replace it with new. After that, I plan to spray mortar over the entire surface
I had to do some repointing in my basement as well. I tackled some drainage issues on the outside, where water was actually seeping in from one corner. But after the repointing, the amount of dampness coming in through the gaps in the Fieldstone reduced drastically. Just make sure you use Limestone based Type S mortar, not concrete mortar. Concrete mortar is stronger than the stone and can cause damage over time due to expansion and contraction.
Hey, I know what you mean… I’ve been there too. 😅 So much work
You can’t fully waterproof the walls. You need to redirect water away from the house using downspouts. Consider using affordable options like trash bag extenders before digging channels or installing surface drain pipes that discharge at least 3 feet away from the house.
I found ways to redirect water away from my house, fix grading around the foundation, and redirect downspouts. Since doing this, I haven’t had any water issues. A basement company quoted me $12k for a sump and drain tiles, but I spent less than $100 on dirt after redirecting my downspouts. During a rainfall, I walked my property and discovered that the water was actually coming from my neighbor’s house.
You’ll want to tackle this from the outside first. Start by digging around the area and applying a waterproof surface product, followed by a physical barrier. Next, use tubing to redirect water away from the house. While everything dries out, lay down tarps and make sure to secure them to the house about 2 feet high to prevent water from reaching your foundation. Use sandbags to weigh them down. ‘t forget to install a dehumidifier in that area.
I’d recommend starting with the outside. Are your downspouts directing water away from your house? How is the ground sloped around your house? My basement walls are made of 200-year-old limestone, but I never have water coming in. You mentioned it only happens after it rains, so that’s why I asked about the outside instead of the inside.
I always recommend ‘ advice to others: go outside during rain and observe how the ground water behaves.
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You have the option to waterproof either inside or outside. We hired a company to dig out the inside, install a drain and sump pump, and then restore everything. It’s been over 2 years and we haven’t had any issues. The other option is an outside French drain, but we were advised to go with the inside option if you have a basement. Good luck!
Exterior waterproofing is definitely the way to go. If you can’t do it outside, then the interior is also an option. It’s always best to go with exterior first. Excess water can cause foundation damage, while the interior method just redirects the water to a sump pump.
After sealing the outside, I recommend installing a French drain with an auto pump.
Just a heads up, if you seal the inside without sealing the outside, the bricks might still absorb moisture but have no way to escape, causing more damage