How do I stop Brahmins from coming into my structures in Fallout 4?

This might not sound like a big deal but it's driving me nuts. A number of my settlements have Brahmins wandering around inside buildings, getting in the way and generally making a nuisance of themselves.

An example is Hangman's Alley, which must be one of the smaller settlements but because of it's excellent position I've put a lot of effort into developing it. I've built a multi-story structure that's partially open on the ground floor (as the existing environment means I can't wall it up).

Every time I visit Hangman's Alley there is a Brahmin stomping around on the ground floor of my structure, blocking the stairwell, making it difficult to use the workbenches, standing on sleeping bags and generally getting in the way.

I then built a Brahmin drinking trough at the other end of the alley, and built a fence (with a gate) between the trough and the structure. But that hasn't changed anything, the Brahmin hasn't gone anywhere near the trough and was still blocking access to everywhere I want to be.

So I shot it, dead. Which sort of solved the problem - I could now get to the stairs/ use the workbenches - apart from the aesthetic issue of having an immovable dead two headed cow in my bedroom.

After a couple of game days adventuring I returned to Hangman's Alley to find the dead Brahmin had disappeared and there was now a live Brahmin back in the ground floor - blocking everything off. Argh!

I tried herding it by pushing/ hitting it (didn't work), I tried to build another fence - but space is very limited and I couldn't build a fence/ gate/ door system that'd allow me and the settlers access the structure while blocking the Brahmin. I've also seen Brahmins jammed in doorways/ entrance ways so I wasn't sure how effective a fence/ gate/ door would be if I could build one.

As I said, it probably doesn't seem like a big deal but it's driving me nuts. I haven't put hours into building my settlements to have noisy ugly two headed cows stomping around and blocking access to my bedroom/ storage/ workshop/ stairways. Not too mention the up close animation for Brahmins is pretty shonky with lots of clipping which makes the whole experience worse.

A few thoughts:

• Do I need to build a fenced enclosure around the trough?
• Do Brahmins automatically appear once a settlement reaches a certain population?
• Is there any way to make a settlement permanently Brahmin free?
• Do Brahmins need shelter or are they attracted by certain items?
• Am I losing my mind?

How do I stop Brahmins from coming into my structures in Fallout 4?

This is the purpose of the Brahmin Feed Trough, available under Resources > Miscellaneous.

As stated in game, Brahmin will tend to stay near their feed trough so if you place a feed trough away from entrances to buildings, all of your Brahmin will gather around it and not wander around the settlement anymore.

Here is a really bad example, where I placed the trough too close to a building and the Brahmin. However, it does demonstrate that the Brahmin will all try to get as close to the trough as possible:

If you build your trough in an enclosure away from buildings you'll generally find the Brahmin will enter the enclosure and stay there. This is demonstrated in the standard arrangement at Abernathy Farm:

Note this won't apply to Brahmin travelling with traders, they seem to do their own thing a lot.

Unfortunately you can't rely on settlers to close doors or gates, and there's nothing you can do to make them close without your intervention.

For Hangman's Alley specifically, it's quite a narrow space so if you walled off the other end of the alley and have the trough outside of the alley this would likely keep them away from your structures.