Jumping monsters will be able to jump over a low wall, so that depends on where you've built this base and what raids you are currently experiencing. Some raid monsters can completely destroy your base even if it is built of stone or iron.

Traps (Mainly the Pointed stakes)attract hostile attention, I think Growing Crops (Not fully grown but immature crops) and all livestock, including tamed animals attract aggro.
The Karve and the Longship, as well as the cart also attract aggro, curiously I've never seen anything but a serpent go after a raft, but I barely use them (Mostly for fishing)

If it doesn't have wings, it won't fly.

Defense in depth. A low wall over which trolls cannot step constructed in multiple layers can be far more economical barrier than a high wall. You'll still want at least 2-3m wall for cover from ranged attacks, but that can be placed behind the outermost walls.

I still haven't seen a single seeker actually try attack my home yet alone try crossing the walls, but at least bats seem to be capable of that. There isn't much of a counter to them other than using the ballista. There may be some way of using the sharpened stakes to fend off seekers trying to fly over walls, not sure.

Thank you for the response, @Rhapsody. I think I'm good then, at least height wise.

I have not seen a raid in my game in something like 150 game days, which is before I ever had any walls in the first place. At this point I've considered using dev command to trigger one just to see how well the walls work (if there even is such a command, though I assume there is).

The main purpose of walls is to break mob line-of-sight (LOS). Mobs won't aggro if they can't see you or any base structures, they'll just wander around alerted outside. For this a stakewall is perfectly acceptable and I always plop down a stake wall around any portal I plan on leaving up permanently or semi-permanently.

As for taking hits, marble > stone > wood. Stone is easy and abundant. I like to make perimeter walls 3 tiles thick so I can hide workbenches and stonecutters inside the wall. The extra thickness also keep trolls from damaging things in your base (either because you built in black forest or "The ground is shaking" event is going). Log trolls can still hit a small area on the far side of a 3-tile wall though, so be at least a little vigilant.

Walls are useless against seekers, bats, and drakes. You have to deal with these events. I like to fight in a spot in base where they're not likely to cause a lot of collateral damage. Open spaces where you can spin around with an aegir and not hit any base structures, drakes aren't going to knock down your roof, same with seekers, etc.

Originally posted by Jaggid Edje:

At this point I've considered using dev command to trigger one just to see how well the walls work (if there even is such a command, though I assume there is).

https://valheim.fandom.com/wiki/Console_Commands#Cheat_Commands

https://valheim.fandom.com/wiki/Events

Let us know how it goes if you're willing to give them a try...

Originally posted by Maelstrom:

The main purpose of walls is to break mob line-of-sight (LOS). Mobs won't aggro if they can't see you or any base structures, they'll just wander around alerted outside.

Oh, that's VERY useful information that I wasn't (at least entirely) aware of. It helps to explain why at my main base, it's so peaceful. The only thing that has ever been attacked is a wagon sometimes when I leave it outside of the wall after gathering wood.

Meanwhile, at some of my smaller outposts, I've had issues with stuff getting destroyed....I haven't been building any kind of walls for those.

You have taught me things, so thanks!

Originally posted by Jaggid Edje:

Originally posted by Maelstrom:

The main purpose of walls is to break mob line-of-sight (LOS). Mobs won't aggro if they can't see you or any base structures, they'll just wander around alerted outside.

Oh, that's VERY useful information that I wasn't (at least entirely) aware of. It helps to explain why at my main base, it's so peaceful. The only thing that has ever been attacked is a wagon sometimes when I leave it outside of the wall after gathering wood.

It's a similar case for me, but I believe that's not the whole truth. I don't know how mob AI really works, but some structures and objects will attract hostile attention even if the players are hidden or away. That was one problem with wisp torches until the latest patch for example.

Edit: Another case is sap extractors and workbenches. Mobs will readily target workbenches but leave the extractors alone. It's rather bizarre.

I put a storage chest at my docks, which are outside my walls, and I built a low stone wall around it with a hatch on top to access the chest. That's been safe out there so far.

I assume chests themselves are not safe if not blocked from view? I saw a greydwarf go crazy on one of those stone tower ruins and destroy a chest that wasn't even one I built.

(The hatch door is from a mod).