Sieges in Graveyard Keeper 2 give you two things to build and three versions of one of them. The towers shoot, the barricades hold, and the menu does nothing to tell you which of the three is worth picking.
It matters more than it looks, because at every tier all three barricades cost exactly the same materials. They are not a price ladder, they are three different answers at one price.
One of those three answers is wrong in every situation, and it is the one called 
Barricade I.
Never build the plain Barricade
Barricade I, 
Fortified Barricade I and 
Spiked Barricade I are all six 
Bronze Nails, two 
Short Log and two 
Reinforced Plank. Same technology, same shopping list, same slot on the wall.
The plain one has 400 health. The fortified one has 600. There is no upside anywhere else on the plain version to pay for that gap, and the pattern repeats at both higher tiers.
Tier I is 400 health against 600, tier II is 600 against 800, and tier III is 800 against 1,000. The per-rank scaling goes the same way, 40 health a rank against 60 at the bottom and 80 against 100 at the top.
So the plain Barricade is not a budget option, it is a worse item at an identical price. Every wall slot you give it costs you 200 health you could have had for nothing.
The real decision is the other two. Fortified Barricade I is the wall you put where the enemy will spend the longest, and Spiked Barricade I is the one that hurts them back while it stands.
Fortified against Spiked, which is the actual choice
Spiked Barricade I trades health for damage. It carries 250 health at tier I against the fortified 600, and in exchange everything that hits it takes 3 damage back.
Those numbers move together as you climb. Spikes go 3, then 5, then 7 in return damage while their health goes 250, 450, 600, so the spiked wall is always roughly half the tank and always the only one dealing damage.
War Supplier adds health, which is worth more on Fortified Barricade III than anywhere else: 100 a rank on the fortified tier III against 60 on the spiked one.
War Engineer adds return damage, and it only has somewhere to land if you built spikes. On Spiked Barricade III that is 3 extra return damage a rank on top of the base 7, which is the only way the walls themselves scale into a threat.
Towers are the only thing on the wall that aims
Archer Tower I is six Bronze Nails, two Reinforced Plank and a 
Reinforced Bow, and that bow in the recipe is the tell: a tower is a bow on a stand. It has 150 health, hits for 8 at range 7, and fires every 0.6 seconds.
Health and damage both double at tier II to 300 and 16, and tier III reaches 450 health and 24 damage for eight 
Steel Screws, two 
Wooden Joint and a 
Battle Bow. The range and the fire rate never change.
A tower is fragile next to any barricade, which is the point of building both. The wall soaks and the tower shoots from behind it, and a tower left in front is 150 health of free experience for the enemy.
What it costs to unlock, and where
All six technologies sit in Metallurgy and they alternate. Simple Barricades is 
60 and 
25 and gives you all three tier I walls at once, which is the same node that makes the plain one redundant the moment you read the numbers.
Archers Tower is the same 60 and 25, then the pairs climb: 90 and 30 for Robust Barricades, 150 and 75 for Reinforced Barricades, with the tower nodes a little dearer each time.
Two fights in the game switch the defenses off entirely and ask you to win on squads alone, so a wall budget is not a substitute for equipping zombies.
The ladder runs from nothing to 144
There are twenty five sieges in the game and they are a ladder rather than a difficulty setting. Defense power is a lock on entry: below the number the fight is closed to you, and at or above it the fight opens. Raising it past the requirement buys you survivability rather than permission.
The bottom of the ladder asks for six and eight, the middle sits between thirty six and eighty eight, and the top asks a hundred and four, a hundred and sixteen and finally a hundred and forty four. Squad count climbs with it: one squad at the bottom, two from twenty, three from fifty six, and four for the last two fights.
Two of the twenty five carry no defense power at all, and they are not free wins. They are second waves that trigger after the fights at seventy two and eighty, so the only way to see one is to win the fight in front of it first.
Your defenders bring nothing but their health
Four Barracks mercenaries carry a hundred and fifty health each, and six city guards carry fifty. Those numbers are the whole of what the game gives them, because their damage, their armor and their reach are all read off whatever they are holding at the time.
That is the sentence worth rereading before a siege. A squad is a set of health bars until you equip it, so the bow and the armor you hand over are the entire difference between a defender and a speed bump. A 
Defender’s Emblem buys another slot to fill, not another fighter.
Every barricade gains ten percent of its health from the perk, whichever tier and whichever type. Archer Tower I gains fifty on a base of a hundred and fifty and Archer Tower II gains a hundred on three hundred, which is a third in both cases.
So the perk reads as a wall investment and pays out as a tower one. If your line leans on towers, take it earlier than the wall comparison above suggests.
What holding the line pays
Every siege pays 
Town Gratitude, which is worth 5 happiness, and most pay 
Zombie goo alongside it. The two that matter more are rarer.
Defender’s Emblem unlocks a new squad slot at the Barracks, and 
Keys for Looters places an order with the Looters at the Port Club. Those come off specific fights rather than every one.
Zombies only fight if equipped with armor and a pike or bow. / The better your zombies’ equipment, the higher the defense rating.
The game, on why your squads are underperforming
Graveyard Keeper 2 Barricades and Towers FAQ
Which barricade should you build in Graveyard Keeper 2?
Fortified or Spiked, never plain. All three cost the same materials at each tier, and the plain Barricade has the least health of the three with nothing to show for it.
What is the difference between the barricades?
Health and return damage. Fortified has the most health and deals none, while Spiked has roughly half the health and damages anything that hits it. Plain has less health than Fortified and no damage at all.
How much health does each barricade have?
At tier I, 400 for plain, 600 for Fortified and 250 for Spiked. At tier II it is 600, 800 and 450. At tier III it is 800, 1,000 and 600.
How much damage do spikes return?
Three at tier I, five at tier II and seven at tier III, plus one, two or three more per rank of War Engineer.
What do Archer Towers do?
They shoot. 8 damage at tier I, 16 at tier II and 24 at tier III, all at range 7 and firing every 0.6 seconds. Their health is 150, 300 and 450, so they are fragile and belong behind a wall.
What does a tower cost?
Tier I is six Bronze Nails, two Reinforced Plank and a Reinforced Bow. Tier III is eight Steel Screws, two Wooden Joint and a Battle Bow.
Which perks help siege defenses?
War Supplier adds health to towers and barricades, and War Engineer adds damage to towers and return damage to spikes. War Engineer does nothing if you only built fortified walls.
Can you use barricades in every fight?
No. Two fights in the game disallow both barricades and towers, so squad equipment carries those on its own.
What do you get for winning a siege?
Town Gratitude, worth 5 happiness, and usually Zombie goo. Some fights also pay a Defender’s Emblem, which unlocks a squad slot at the Barracks, or Keys for Looters for the Port Club.
