Project Zomboid Build 42 Barricades: What Actually Holds a Door

A Steel Sheet is worth 5,000 points of barricade health. A plank is worth 1,000. That five-to-one gap is why most survivors treat the first Welding Torch as the moment a safehouse graduates from boarded-up to fortified.

It is the wrong comparison. Nobody nails one plank to a window — you nail four to each side, and a sheet occupies an entire side by itself. The honest match-up is 4,000 against 5,000: a 25 per cent edge at its best, paid for with a tool chain, your line of sight through that opening, and the ability to take any of it back off without a torch in your hands.

Build 42 did not change this. It renamed the parts — Metal Sheet became Steel Sheet, Metal Bar became Steel Rod, the Propane Torch became the Welding Torch in 42.0.0, and the Metalworking skill became Welding — but PZwiki records that both the barricade health values and the barricade recipes are still the Build 41 implementation, "planned to be revamped to Build 42 at a later date". The numbers below come out of that untouched code and the wiki tables built from it, which is why a decompile stamped 41.78.16 still describes exactly what happens when a zombie starts hitting your kitchen window tonight. Including the part where levelling Welding makes your metal barricades worse.

Four Planks a Side, One Slab of Metal

Four planks per side is not how survivors happen to board a window, it is the ceiling. Each face of a door or window accepts up to four, and both faces can be barricaded from their respective sides, so eight planks is the full wooden allowance for a single opening. A steel sheet takes one install per side, and so does a set of steel rods — two per opening, and the face is full. Four slots against one is the structural difference between the materials, and it is the one that quietly rewrites every number you have been told about them.

Each plank is its own object with its own health. A zombie works through a boarded face one plank at a time; nothing on that side comes down in a single hit, and the three planks behind the one being chewed are untouched until it is gone. Metal has no such interior. A sheet is one slab with one health pool, and when that pool empties the face is bare.

The two systems also refuse to share a face. addMetal() and addMetalBar() both check getNumPlanks() and return immediately if the count is above zero, so a single surviving plank on a side is enough to reject a sheet outright. There is no partial upgrade path and no hybrid face: wood or metal, chosen once per side, and the metal stays until you take it off.

Stacked up at base values, before any skill modifier touches them:

Read it per side, never per item

Take a ground-floor kitchen window and finish it properly from both sides. Eight planks and sixteen nails buy 8,000 points of barricade. Two Steel Sheets buy 10,000. That is the whole prize for the tool chain — 2,000 points on a fully committed opening — and the bar barricade, at 6,000 for the pair, sits below the wood it costs so much more to install. The moment you compare a plank to a sheet you are comparing a quarter of a face to a whole one. Five to one is the wrong ratio; five to four is the right one.

Layers buy something the raw totals do not show, either. A barricaded door or window takes no damage itself while any barricade remains on it — the frame underneath is untouchable until the last plank or the last slab is destroyed. So the barricade is not padding on top of the opening's own health; it is a substitute for it, and the opening only re-enters the fight once the barricade is finished. That matters most for the openings you never think about. An unbarricaded window can be smashed in as little as twenty in-game minutes — a single plank on it means the window is no longer the thing being attacked. And whatever ends up hitting it will be standing: crawlers cannot attack a door or window at all, so the entire threat model for an opening is upright zombies working through your layers in order.

The practical consequence is a sequencing rule, and it is the cheapest mistake to avoid in this entire system. Never half-board a face you intend to sheet later. Two planks nailed on now as a stopgap are two planks you have to pry back off before the torch will do anything, and the game will not tell you why the option is missing — it just will not appear. Decide the material for a face before you touch it, then commit.

These are base numbers. What actually gets written into a barricade's health when you install it is this figure multiplied by a barricade strength modifier — and for metal, the skill that modifier reads is not the one you would expect.

Welding Level Two Makes Your Metal Weaker

Two functions decide what a barricade is actually worth when you install it, and between them they are the barricade strength modifier that turns a base figure into the number written onto the wall. Wood calls getBarricadeStrengthMod(), which reads Carpentry — the skill you were already levelling by boarding things up. Metal calls getMetalBarricadeStrengthMod(), and that one switches on Welding levels 2 through 10 first. Only if your Welding is 0 or 1 does it fall through to your Carpentry level instead. Anything else returns a flat 1.0.

Both functions climb the same ladder, but they read it off different skills — Carpentry for planks, Welding for steel:

Read the fallback rule again, because it is the trap. A survivor with no Welding at all gets their Carpentry multiplier applied to steel. At Carpentry 10 and Welding 0, a Steel Sheet is installed at 1.5 × 5,000 = 7,500. The moment that same survivor takes Welding to 2, the metal function stops consulting Carpentry entirely and uses the Welding level it now has — 1.10. The identical sheet, on the identical wall, goes in at 5,500. Learning the skill that is nominally about working metal costs you 2,000 points of barricade per side, a 27 per cent downgrade, and nothing in the game tells you it happened.

Welding 6 is worse than Welding 5

Level 6 is the second trap, and this one hits everybody. The metal switch returns 1.16 at Welding 6 where the wood ladder returns 1.26 — a transposed digit, spotted and reported as a bug by the code reader who first published the decompiled function in 2021, never fixed, and still visible in PZwiki's published health table today. So the barricade strength modifier does not climb monotonically, and the health table built on it inherits the dip:

Welding 5 gives you a 6,100 sheet. Welding 6 gives you a 5,800 one. The level-up is a demotion, and it stays a demotion until level 7 pulls you back above where you were.

What one skill book costs you

Picture the concrete version. You have Carpentry 10 from a month of building and boarding, you have scavenged four Steel Sheets, and you plan to seal the two ground-floor windows tomorrow. That evening you find Welding I: "Basics of Welding" on a shelf and read it, because reading skill books before doing a job is a reflex. You wake up at Welding 2. Yesterday those four sheets would have gone in at 7,500 each — 15,000 per fully sealed opening. Today they go in at 5,500 — 11,000 per opening. One night of reading cost you 4,000 points on each window, 8,000 in total, and every one of those points is now permanent, because a barricade's health is written at install time and never recalculated.

Worse, at Welding 2 that maxed carpenter should not be using metal at all. Their planks are worth 1,500 apiece — 6,000 a side, 12,000 an opening — which beats the 11,000 the sheets deliver, using material they can cut from logs. The tool chain has bought them a net loss.

Wood also feeds itself. Every plank you nail up pays 0.75 Carpentry XP, so the act of barricading raises the multiplier applied to the next barricade you build. Welding gets none of that: it is trained on stripping car wrecks and on cutting and fabricating steel sheets, none of which is barricading. The skill that governs your metal barricade health is one you level somewhere else entirely, on jobs that have nothing to do with the wall in front of you.

Which turns the whole thing into a sequencing problem rather than a skill problem. If you intend to sheet the house and you have decent Carpentry, sheet it before you touch a car wreck — Welding 0 hands your Carpentry multiplier straight to the steel, and that is as good as metal gets for a carpenter. If you have already started levelling Welding, do not park it. Two is the worst place to stand for anyone above Carpentry 2, and six is worse than five for everyone. Push to 7 and the sheet is finally worth 6,500; push to 10 and it is 7,500 again, which is what that same carpenter was already getting before they learned to weld at all. Anything in between is a level you paid for that made your safehouse weaker.

The Third Plank Is Where You Go Blind

Health is only half of what you install. The other half is what you can still see through the opening afterwards, and a plank barricade charges for that on a threshold rather than a slope. One plank on a side leaves the window transparent. Two still do. The third is where the face goes opaque, and the fourth changes nothing because you are already blind. So the wooden ladder has a break in it that has nothing to do with the numbers: planks one and two are free, planks three and four cost you the view.

That leaves the strongest see-through wooden arrangement at two planks a side, both sides — 4,000 base on the opening, half of what a fully boarded one carries. Metal does not have a threshold, because each metal face is a single object that either occludes or does not. A steel sheet barricade always blocks line of sight; there is no partial install and no way to put one up and keep the window. A metal bar barricade never blocks it.

That single property is the whole argument for the metal bar barricade. Two bar faces put 6,000 on an opening and leave it transparent, against 4,000 for the best see-through wood — a 50 per cent edge on exactly one axis. Compare bars to a fully boarded opening and they lose, as the base table already shows. Compare them to the only wooden configuration that also lets you watch the street, and they are the strongest face in the game. Bars are not a general upgrade over planks. They are the answer to one question, asked one opening at a time: must I still see through this?

Doors change the question rather than answering it. The visibility rule only bites on the door variants with a window pane in them — a solid wooden front door had nothing to see through before you touched it, so three planks take nothing away. What a door barricade does take away is the door. Barricading a door removes your ability to open it at all until the barricade comes back off, in either material, so a boarded door is a wall with a handle on it. That, not sight lines, is what decides door policy: you are not choosing a material for a door, you are deciding whether the house still has that exit.

Two openings show both rules working at once.

• The upstairs bedroom window you watch the street from. This one has a job beyond holding: it is how you know whether the horde has drifted onto your block before you commit to a supply run. Four planks turn it into a wall and you lose the intelligence. Two planks a side keep it, at a base 4,000. Two bar barricades keep it at a base 6,000. This is the opening the torch was worth carrying for.
• The front door you still walk through every day. Sealing it is the whole cost, so the material never enters into it. If you still come and go through that door, it gets no barricade at all — its defence is the lock, and a second exit you have already sealed and can still open with the tool in your hands.

Curtains are worth knowing about because they trade the opposite way. A curtain on a window blocks line of sight in both directions and opens only from the inside, so concealment becomes something you switch rather than something you nail on permanently. Two planks plus a drawn curtain hides you exactly as well as four planks do, and unlike four planks you can pull it aside and look. The blind third plank buys strength and nothing else — if what you wanted was to not be seen, you were never short of options that leave the glass clear.

Three Damage a Swing, and You Can Keep Feeding It

Damage coming off a barricade is far simpler than the health totals going onto it, because a barricade is the one structure in the game that takes it without any crowd arithmetic attached.

IsoBarricade.Thump() calls Damage(((IsoZombie)thumper).strength * ThumpState.getFastForwardDamageMultiplier()). That is the whole calculation. The attacking zombie's strength, scaled only by a multiplier that tracks time compression. There is no check for how many zombies are on the tile, no scaling for a pressed crowd, no threshold that has to be met before the hits register. Strength is 1, 3 or 5, set by the sandbox Zombie Strength option — Weak, Normal, Superhuman — and both Apocalypse and Survival run Normal. So on a default save, every swing that lands on your barricade removes exactly three points, whether one zombie is hitting it or thirty.

That flatness is unusual, and it is easier to see next to the two structures a barricade sits between. A pre-built world door takes no damage at all unless at least two zombies are on or beside its tile — a lone wanderer can pound a bare front door indefinitely and never mark it. Player-built walls are stranger still: they take one point per thumping zombie only once eight or more are nearby, and below that each contributes a fraction of a point — one eighth from a single zombie — with strength ignored entirely. Barricades get neither protection. The first zombie to arrive does full damage on its first swing, and the hundredth does exactly the same damage as the first.

At Normal strength, that converts health into swings directly:

What the table does not say is which of those faces you can do something about while the swinging is happening.

Put one zombie on your barricaded front door and the arithmetic turns strange. While the barricade stands, the door underneath takes nothing at all — the barricade is absorbing everything, at three points a swing. Suppose the zombie stays and finishes it. What it reaches then is a bare pre-built door, which takes no damage unless at least two zombies are on or beside its tile. A lone wanderer can pound that door for the rest of the save and never mark it. So on a door, a single zombie can only ever destroy the thing you added, and never the thing that was already keeping it out. The barricade did not protect the door; the door was never in danger. The barricade bought you the noise.

That noise is the point. Barricades are loud when struck, so a boarded window on the far side of the house announces which opening is under attack while there is still time to walk over and do something about it — which is only useful if there is something you can do.

The repairs you can make, and the one you cannot

A damaged barricade cannot be patched. PZwiki is blunt about it: barricade health cannot be upgraded or repaired, only removed and reapplied. That is the end of the discussion for metal, because a steel sheet barricade is one slot with nothing behind it — when its health reaches zero the face is bare, and it stays bare until you strip the frame and install a whole new sheet.

Wood is exempt for a reason that has nothing to do with repair. Look at addPlank(): the function walks the four plank slots, skips every one whose health is still above zero, and fills the first slot that has dropped to nothing. It is not patching a damaged plank, it is occupying a slot that a destroyed plank has just vacated. So a plank barricade accepts a fresh plank the instant one of its four is gone, while the other three are still standing and still absorbing hits — no removal, no rebuild, no interruption to the face.

That changes what the health totals mean. A steel sheet's 5,000 is a ceiling: the most damage that face will ever absorb before it fails. A four-plank side's 4,000 is a rate. Every plank you renail during a siege is another 1,000 points fed into a face that is already holding, and the only limits are your plank supply and whether you can stand at that window without something reaching through it.

One caveat governs how much a renailed plank is actually worth. A plank carries its own condition into the barricade: a plank at half durability nailed to a window contributes half a plank's worth of strength to that face, not a full one. And planks pried off existing house barricades come back damaged from whatever the zombies did to them before you arrived. So a mid-siege repair made from salvage is a partial repair, and the same slot refilled with a fresh plank is worth more than the same slot refilled with something you tore off a boarded shop window last week. Keep the intact planks for the openings you expect to hold under pressure.

So a steel sheet barricade is a fixed budget: better while it lasts, gone the moment it empties, and no help at all until you come back with the means to install a whole new one. Which raises the question of what installing one costs in the first place, and when in a run you can afford it.

Wood Is Free, Metal Is Rented

One plank and two nails. That is the entire material bill for a plank barricade, and it is why the wooden option is available from the first hour of a save. The only other requirement is a hammer in your inventory to open the menu: Claw, Ball-peen, Stone or Smithing. A Club Hammer will not open it and neither will a Sledgehammer, which is worth knowing before you clear a house carrying the wrong one and find the option missing at the window. The nails have to be loose, too — a sealed Box of Nails (100) in your bag counts for nothing until you open it, and a hundred nails in a closed box will leave you unable to place a single plank.

There is no skill gate anywhere in that list. Carpentry 0 boards a window; Carpentry only shortens the action and, as the health table showed, decides what each plank is worth once it is up. A full opening runs to eight planks and sixteen nails, and one log saws into three planks, so three logs and a saw cover a whole window with a plank in hand. Wood is the only barricade material in the game you can manufacture from a tree.

Metal is bought, not made. A steel sheet barricade is one Steel Sheet, weight 2, plus one use of the welding torch. A metal bar barricade is three Steel Rods at 1.5 weight each — 4.5 for the face — plus the same single use. The rods carry a small rebate: a Steel Rod is a serviceable short-blunt weapon that attaches to your back, so at least one of the three is weight you might have been carrying anyway.

The torch is the real constraint, and it runs on a clock. UseDelta = 0.1 means ten uses in a full Welding Torch — ten faces, or five completely sealed openings, before it is dry. Refilling from a Propane Tank costs a flat 1/16 of the tank no matter how much fuel the torch already holds, so a habitual top-up at half empty throws away five uses every time. Run the torch to zero before you refill and one tank is sixteen fills; refill it whenever you pass a tank and you will get a fraction of that. What metal does not cost is preparation: barricading needs no welding rods and no learned recipe, which makes it unique among welding actions. The hour you find a torch you can weld a sheet over a window, with no book and nothing but fuel.

The two sources disagree on one item. PZwiki's extracted recipe still lists a Welder Mask as required for both metal barricades; the pzfans Build 42.19 guide states the mask is no longer needed and calls the wiki's requirement outdated. Carry one regardless. It costs a slot, it settles the question the moment you stand at the wall, and if the newer guide is right you have lost nothing but the slot.

A ball-peen nails planks on but cannot pry them off

Wood comes off with a claw hammer, crowbar, tire iron or firefighter axe. The asymmetry to watch is the ball-peen: it opens the barricade menu and drives planks in perfectly well, but it cannot take one back off. A survivor who boards a whole house with a ball-peen and nothing else has built something they cannot open. Metal comes off only with the torch, returning the whole Steel Sheet or all three Steel Rods, and burning fuel on the way out as it did on the way in. Planks and metal are always recovered. Nails never are — every opening you change your mind about costs sixteen nails you will not see again.

That is the actual price gap, and it is not measured in barricade health at all. A plank barricade is a decision you can take back in the field with a crowbar you already carry. A steel sheet barricade is a decision you can only take back with the same tool chain that installed it, and it charges you fuel to change your mind.

The window when metal is actually worth it

Two things have to be true at once before a sheet beats a plank, and they pull in opposite directions across a run.

The first is knowledge. Metal only pays on a face you never intend to touch again, and on day 3 you do not yet know which faces those are. You have a hammer, a saw, some logs and whatever nails the house gave up, and every ground-floor opening gets planks because planks are what exist. By month 3 you know exactly which door you walk through, which window you watch the street from, and which back bedroom you have not entered in weeks. That list is the sheet's entire target.

The second is your Welding level, and this is where most runs go wrong. Metal is at its strongest for a carpenter who has never welded — Welding 0 hands the Carpentry multiplier straight to the steel. But a survivor three months in has usually stripped a car wreck by then and is sitting at Welding 2, where a Carpentry 10 sheet is worth 5,500 against 6,000 of wood. The very experience that tells you which openings to seal is the experience that has already made your sheets worse than planks.

So the good window is narrow and you have to protect it: high Carpentry, Welding still at zero, and enough weeks in the house to know its dead faces. If you are there, spend the sheets before you strip a single wreck. If you have already passed Welding 2, do not sheet anything — board it in wood, take Welding to 7 or better on wrecks and steel sheets, and come back to the job when the multiplier is worth having.

Then work the house opening by opening, torch in hand, with the questions in this order. Do you still walk through it? Then it gets nothing, and a lock. Do you need to see through it? Then a metal bar barricade or a two-plank face, and no sheet will ever be right for it. Can you stand at it safely from inside while zombies are hitting it? Then planks, because a face you can keep feeding beats a face that is stronger exactly once. What is left over — the far window nobody watches, the side door you have written off, the ground-floor room you sealed and stopped entering — is what the sheet is for, and you have ten uses in the torch to spend on it.