Greetings!

We have a house that has a small leak. The water appears to be coming up from between the concrete floor and the poured concrete wall/footing. It's slow but enough to soak 5 full towels in an hour. It's coming from one side of the house, mostly in one corner.

We get our perimeter drains snaked twice a year, once in the fall and once in the spring. There has not been any issue.

I fear because we are on the lower end of a sloaping hard pan, we are getting everyone else's perimeter drain water. I talked to a neighbour and he said in 20 years of living there, he has never snaked his perimeter drains. I believe this is indicative of the entire neighbourhood. Why fix it if it's not a problem.

We do not have a sump pump. We have a finished basement with tile floor. If a sump pump is our answer, it has to be the final solution before we chip up the floor.

We are not sure what to do. Any suggestion? Please, ask any questions if you need clarification.

Thanks for reading!

 

When you say perimeter drains, are you talking about foundation drains at footer level, or higher drains used to drain roof spouting? Where do the drains drain to?

Seepage like this sometimes occurs at the high end of footer drains. The footer drains must have slope so they empty and often the end farthest from the low end is barely below the level of the slab.

Anything you can do outside to keep water away from the foundation may help, but if the problem is that the exterior footer drain is too high in this area, then addition of a sump pump may be the most practical solution.

 

There are a variety of corrective actions. Concerning basement flooding, any corrective action needs at least a week under adverse weather conditions to be in effect before you can draw conclusions as to whether it worked. So you have to make the choice of doing all the actions at once to solve the problem faster and never know which method was the saviour, or do the actions one at a time (giving each a few weeks) and stop when the problem is fixed.

You need to have a perimeter drain pipe or drain tile system below the level of your basement floor. If your existing perimeter drain is too high then you will need to install another perimeter drain, this one below the level of your basement floor.

Where does the water in your perimeter drain ultimately go as you see it. The purpose of a sump pump is to collect the perimter drain water so that water can be pumped out and away from the house.

Water makes its way to the perimeter drain by seeping. It is sometimes although not always necessary to fill cracks in the foundation including where the slab floor meets the foundation wall so water does not find those cracks prior to seeping all the way to the subfloor perimeter drain.

Contrary to popular belief you do not need and usually you cannot use the usual quarter inch per foot slope for your perimeter drain tiles or pipes. When retrofitting a house with a perimter drain you must not excavate below the bottom surface of the footing or below an imaginary flat surface within the ground extending out and down from there on a 1:3 vertical to horizontal slope. And the drain tiles must be wholly below the floor surface. Even with a one millimeter drop per 3 foot 3 inch (one meter) horizontal run, water will still make its way to the sump pump pit.

 

I'm so sorry about the late reply. We had another slow flood and tried to source the issue. This time it happened during a 24 hour rainstorm.

Here are some answers/notes to your replies:

1. We have a perimeter drain and it is indeed below the basement cement floor by about 6 inches at the highest point. These perimeter drains have up-spout accesses at 3 of the 4 corners of the house. We use to use them to clean them out but now we call someone in to do it for us. The drains use to be tile. Now, the majority of them are PVC however, there is about 1/4 of them are
still tile. And yes, that is the area of the flooding. More on that in a bit.

2. The perimeter drain is low. We also have the drains for the eves. Those drains are higher but still 3 feet below the grade. There is a small sump in one back corner of the house (just for the eves draining and the yard draining (more on that in a bit)) and a sump at the front-center of the house. This is the big one that drains to the city (with a check valve). There is also a collection drain for the perimeter drains next to the front-center sump. Everything runs. I have forced water down every point and I can see water running every time. So, no major clogging.

3. Yard draining. When we had the perimeter tile replaced with PVC, we also ran a bunch of drains around the back yard. They are only a few feet deep but they collect a large amount of water from the soil and drain it into the small sump. Those have never been an issue and they keep the back yard from turning into a swamp. There is constants flow from that sump to the collection in the front of the house and from there to the large sump and then to the street.

4. The area of the flooding. These are drain tile. We have PVC run to the point of where we cannot access the tile because of structures/walkways in the way. I know it's easy to say, "old drain tile is the problem!" and it very well could be but it flows with almost no problems. This runs from half of one side of the back of the house, around the corner and to the front-side corner of the house where we have an access point to clean out from.

4. Sloping. The slope of all perimeter drains are fine, unless there has been a collapse or a sinking that I cannot find. As far as I can tell, there is no issues with the sloping. I have run water in all points to be able to see the flow and even at it's highest, the running water never rises above 6 inches below the basement flooring. This would be the worst case scenario in terms of water in the pipes being too high, and with seeping, water would never get this high. I even clogged the area and tried to fill the drain with water and it never filled telling me one of two things: 1. The drains are working (but in reverse when I am adding water), or there is a major hole that is leaking the majority of the water. When I pulled out my clog, water flowed very well until there was no water left.

5. There are no pumps. All sumps are gravity driven and work quite well.

In my head, I am seeing the sand under the basement floor being completely saturated with water to the point of some kind of a hydraulic pressure forcing water up between the footing the the basement floor. I could be way off here.

If I needed to, would a sump pump need to be installed inside or could I put it outside?

Please let me know if I can help out with more information. This is a tough one.

 

You've covered a lot of the bases. Since this only happens during big rains, I doubt the problem is high water table under the slab. A broken spot in the drains seems more likely.

Since you have good access to all the lines, consider a video inspection. You can have it done professionally or you can buy inexpensive pipe cameras. They don't self orient (so down on screen may be up in pipe) but they are good enough to spot big issues. Most of inexpensive ones aren't good at turning corners though.

I have outdoor sump pumps draining my foundation drains since I have a dead flat lot and there are no sewers here. So you can do it. But it's a lot easier to monitor/test/and repair an inside sump pump than one that is 10 feet down in a hole.

 

If it is not a big job.....hire someone with a jack hammer to chip out the seam between the floor and the footing...and cram hydraulic cement (Zypex?) or similar into the gap.

It might work....and than again, it might not work.