Of course it will. That's the point of it, at least from the neighbor's point of view.

You need a solution that drains the water away from that spot. You could grade a swale to channel the water or install a French drain to dump it out someplace else.

If you don't, the net effect of that concrete wall will be that the water will end up in the neighbor's yard just as it does now; it will just drain more slowly as it goes underground around the end and underneath. The footer is completely useless to stop the eventual flow of that water.

Thanks so much Tatts and Yardvaark! This was so helpful. These problems you mentioned are the types of problems I am worried about. Thanks so much for confirming that.

Thank you for stating this so clearly: "General rules of drainage are that people cannot concentrate water flows onto someone else's property, nor can they block the natural flow of water from coming onto their property. "

I will see if my husband is okay with posting photos.

Our garage is also about 3' from the fence and it worries me that the concrete footing could also damage our garage.

"I will see if my husband is okay with posting photos." I must both laugh and grimace at that line. If this is in the front yard, no one has any legal right to privacy and should have no expectation of the same ... unless they're rich and live behind tall walls in a gated yard. Then, they get whatever they want, whenever they want. The rest of us must endure the press, or even wandering vagabonds taking photos of our shrubs and flowers anytime they want. But not showing photos is like asking the doctor to diagnose a skin rash over the phone. It's not gonna happen.

I did not read Tatts remarks until now, but it seems he or she is saying that whatever water problem you get on account of the neighbor's project, you can deal with by having your own grading or drainage project, in order to solve what the neighbors caused. That would not appeal to me as a solution now. If I purchased a piece of property and later discovered that a drainage problem had been created 20 years earlier, then I would be content creating my own project to resolve it.

Yardvaark: Actually I meant that as long as the site is dug up for the concrete wall it would be an easy thing to put in a French drain behind it (where it dumps out is another issue) or make a swale as the earth is replaced. But without pics...

The house behind us flooded so badly after a storm (same storm that flooded the airport parking garage in Baltimore) that the basement wall collapsed. When they rebuilt the basement wall and did the finished grading, the new grading changed things to where I suddenly started getting 6 inches of standing water in my backyard. And yes, they're downhill from us. It doesn't take much to cause problems. Your spouse needs to be a little more risk averse.

I like my next door neighbor. If he was proposing something like this, I'd explain my concerns and offer to split the cost of a consultation with an engineer to make sure there are no problems looming. I can't stand the people who own the rental behind us, so the problem that they created for me escalated immediately to the town engineer and our attorney. Your solution is somewhere in between.

So this is a duplicate post and there are answers on the other one how many times do you need to be told this is a bad idea and unless you do something about it now you will have nothing but problems.

So... this thread is just a continuation of this thread? https://www.houzz.com/discussions/5711754/neighbor-digging-on-our-property-to-build-retaining-wall

That's kind of confusing...

I am trying to plan a privacy fence and a significant amount of new landscaping which is a difficult project in re neighbors. Last week i had a visit from a highly-credentialed landscape designer (from a firm that does mostly large projects, commercial projects) so I could get some basic info and ideas. She suggested that she could come back and meet w my husband and me and also the neighbors to see if we could all cooperate in plantings of trees and large shrubs that would create more privacy, for example staggering a planting line so some are on neighbors and some are on our property. She said she has had a lot of training and experience in getting various people or groups on board with a cooperative project. I wish you could find someone like that to ascertain the goals of both your family and the neighboring family, and then draw up plans to achieve the goals and keep everyone happy. . . . By the way, I would not recommend putting a structure across both properties. Your thing at your expense on your property. Their thing at their expense on their property. imho.

We are paying for a drainage consultant to look at the situation. Will let you know what they say.

Are you sure about that?