Reader question: What are the rules for a separation wall

Dear Fred,
If you want to become/stay good buddies with your neighbor (better a good neighbor than a distant friend), I would still talk to him, with your wife present.
Then you can find out something about how high and hay is beautiful, and possibly arrange the costs together.

well, quarreling neighbors about that little wall or that leaning tree are real fodder for the Riding Judge!
Give me the Thai solution: free and match…
A Wai instead of an elbow punch!

Well, not like in the Netherlands, where you need a permit for everything.
My Thai mother-in-law was annoyed by the neighbour's cow, the cow came to her land.
After some "warnings", she had ordinary concrete, 1m7 high, posts installed with barbed wire through them. That really runs on the separation of the land and right past the neighbors house.
These can walk straight into the barbed wire when they leave the house, bizarre, you really have to be aware of that barbed wire, but yes, the cow does not enter the country in any case. No permit, nope, just placed, her country.

At the time, we had had a wall built with the neighbors and shared the costs of the piece between their piece of land and ours. That piece of land belonged to the neighbor's sister and she lived next door. They had a construction company and set up a construction shed for about six families on that piece of land.
These had raised floors and they could look into our garden without hindrance. During the day most of them were working so it didn't bother me, but when we sat outside having breakfast in the morning they stood there unabashedly staring at us.
My wife in particular was annoyed by that. So I started raising the wall (about half a meter).
Two years later I suddenly heard from this neighbor that she felt very disturbed that we had done that and she felt like driving down the entire wall. The quarrel had started when I got rainwater in through that wall in a shed that I had built against the wall. I asked her how I could putty that piece there, because in the meantime a biting dog was walking on that large piece of land. Then she got angry, because everything was broken because we had simply raised the wall. Which is sheer nonsense.
We haven't talked to her since then. Her husband has run off with another woman, and she's kind of a “little lady” who knows better…. not the kind of person we like to hang out with.