This may be long, or a noob question, not sure, but I just want some help I guess. I generally play as a Soldier, only play as the other classes when I have a daily mission requiring it, so don't really know the strengths of them. I always play on my own, so pretty much everything I've learnt so far, I've picked up Fortnite Items watching other players.

I was doing a twin Atlas mission this morning, Canny Valley PL64. Four players. I started building around the first Altas while the other players ran around clearing the zone. I fully enclosed the Altas in level 3 metal, with a flat roof, then a pyramid on top of the flat roof. Next I put low walls surrounding the build all around the edges, and upgraded these to level 3. I've seen other players do this in my time with the game, never really had a problem.

Then 2 of the other players arrive and start building around the other Atlas and putting traps down. One of them, a Constructor (not sure which variant, the fat guy with a beard) proceeded to smash all of my low walls up, all around the build.

Thought he was just being a jerk, but when I saw he'd built other stuff I guess not. I put low wooden walls around it, and he smashed these too. Then I had an Xbox message from him saying I need to learn how to play the game. Didn't reply, just blocked and carried on playing.

So really, TLDR, I guess my question is why would another player smash up my builds that weren't in the way when they were actually defending the Altas for no foreseeable reason?

Well, it's kind of a jerky thing to destroy other people's builds without asking first, IMO, and he definitely could have handled that another way. Like "here, check out this other atlas to see a better way to build this defense in the future". Or something like that.

That said, there are definitely some builds that are more effective/efficient than others and therefore "meta". In the case of atlases, there are two:

The first is a pyramid with a flat top. The advantages of a pyramid build are that it offers 360 visibility, requires few if any traps, and if something triggers a smasher's charge, it will charge right up and over the top of the pyramid and not do any damage. It's best to leave a flat top so that people can drop their BASE, or traps, or defender posts, or TEDDY or whatever. Though you can build arches and a roof if you want to put a gas trap on top or something. You can also place floor traps along the slanted sides (build the sides with slanted roof tiles, not stairs for this reason). It's not necessary to build short walls around the pyramid, but it doesn't really hurt. It WILL trigger smashers to charge, however, so people tend to not like it.

Pyramids are probably the best build for multi-ATLAS missions. They are fastest to build and repair and easiest to move around on.

But you can also build around an atlas like you should build around the balloon in RtD. Surround the ATLAS with 4 inverted stairs (facing outward) then place a floor launcher underneath each. The idea is the same here: Smashers will not charge inverted stairs (or roof slants) and the floor launchers will keep the other husks away from the build. You can also build a mini kill room that they get launched into. Just google "inverted ATLAS build" or "retrieve the data build" to get a better idea.

Lastly, try to build in whatever material is appropriate. This isn't always possible because you might not know what type of storm it will be until you start the defense, but if you know ahead of time that it's an Ice Storm, you definitely don't want to build in brick. I see people building out of the wrong material all the time and that's kind of frustrating.