Survival Log Doors and Windows: Which Barrier to Fit

The short answer

Fit on all 3 doorways before you touch a window. It holds 3.27 times what Reinforced Wooden Door holds where the printed hit points claim only 1.82 times, because the reduction and the hit points multiply. The doorway is also where nearly every horde arrives.

Holds when: The doorways take 329 of the 597 zombies the scheduled hordes send at an opening and the house has only 3 of them, so one doorway carries 2.9 times what one window carries.
What it costs: The top tier is the dearest row on the shelf on the price the equipment list prints. It is also the cheapest on the price its package carries, and nothing in the data says which of the two you are charged, so no rate per dollar on this page is worth acting on.
Otherwise: If the run is aiming at Safe House, buy the top tier of both regardless: the line names 2000 door durability and 1500 window durability, and only Titanium Door and Bulletproof Window reach them.

Where the run is The first days Running the house Reaching an ending

The first days

The first 2 hordes on the calendar, on days 7 and 14, send every zombie they send at a doorway and none at a window. Put whatever you can afford on the 3 doorways and leave the windows bare. Reinforced Wooden Door takes 1.7 min to fit and takes 5.0 min, so either is a job for a quiet morning rather than the hour a horde is announced.

Running the house

From day 15 onwards every horde splits itself across both openings, and the split grows: the heaviest one sends 128 at the windows alone. Finish the doorways at the top tier first, then work the windows. holds 2.45 times what Reinforced Wooden Window does, and there are 7 of them to pay for against 3 doorways.

Reaching an ending

The Safe House line is measured on day 71 against durability, which is the printed hit points and not the effective figure the rest of this page uses. It asks 2000 on the door and 1500 on the window, and only and reach them. Buy both, on every opening, whatever the rate. The three endings you build for has the rest of what that line counts.

Open the equipment list Every barrier with its hit points, the damage it takes off and the price the list prints. This opens on the Titanium Door, the strongest thing that fits a doorway.

A barrier does two things to an attack and the game shows you one of them. It has hit points, which it prints, and it takes a share off every hit, which it does not print anywhere you can compare. The two multiply: a barrier that takes half the damage lasts twice as long at the same hit points. So the figure that decides how long an opening holds is hit points divided by the damage that still gets through, and it can be far larger than the number on the label.

This page covers what each door and window withstands, which openings the hordes actually arrive at, what fitting one does to the opening, and what the Defence ladder does and does not gate.

What the printed number leaves out

Every barrier a player can fit, by what it actually withstands. The last column is hit points after the reduction.
Barrier	Fits	Hit points	Damage taken off	Fitting time	Holds out like
Reinforced Wooden Door	Door	1100	10%	1.7 min	1222
Security Door	Door	1500	20%	3.3 min	1875
Titanium Door	Door	2000	50%	5.0 min	4000
Reinforced Wooden Window	Window	1100	10%	1.7 min	1222
Security Window	Window	1300	20%	3.3 min	1625
Bulletproof Window	Window	1500	50%	5.0 min	3000

prints 2000 hit points against 1500 for , which reads as a 33% improvement. It actually holds 2.13 times as long, because it takes 50% off every hit instead of 20%. Against Reinforced Wooden Door the gap is wider again: 3.27 times, where the label offers 1.82.

Front Door — The doorway is one place that holds one barrier. What you fit there is the whole of the wall at that point, so what matters is the most it will hold and not the best rate.

The price is the part the data does not settle

The two prices the game carries for the same barrier, and the effective hit points a dollar of each buys.
Barrier	On the equipment list	On its package	Per list dollar	Per package dollar
Reinforced Wooden Door	$30	$60	40.7	20.4
Security Door	$60	$60	31.3	31.3
Titanium Door	$100	$80	40.0	50.0
Reinforced Wooden Window	$30	$60	40.7	20.4
Security Window	$60	$30	27.1	54.2
Bulletproof Window	$100	$40	30.0	75.0

The two columns of prices disagree on 5 of the 6 barriers, and they disagree in both directions. That is not a rounding difference. It reverses the ranking. On the list price Security Door is the worst rate on the shelf at 31.3 effective hit points per dollar and Titanium Door is merely level with Reinforced Wooden Door. On the package price Titanium Door is the best rate of the six at 50.0 and Reinforced Wooden Door is the worst at 20.4. The whole-house bill inverts with it: the weakest tier everywhere is $300 on one price and $600 on the other, against $1000 and $520 for the strongest.

Nothing in the game’s tables says which of the two a shop screen charges, which is the same finding what you are really buying reached across the whole build shop. So this page ranks barriers on what they withstand and on where the hordes arrive, and it does not tell you which tier is the better buy per dollar, because the data does not know.

Where the hordes actually arrive

Every horde on the calendar, and how many zombies it sends at each kind of opening.
Day	Horde	At the doorways	At the windows
7	Zombie Siege	6	0
14	Zombie Horde - Phase 1	6	0
15	Zombie Horde - Phase 2	6	4
34	Zombie Horde	28	14
49	Zombie Horde	53	38
61	Major Zombie Horde	78	70
75	Enhanced Zombie Horde	133	128
95	Zombie Horde	19	14

The house has 3 doorways and 7 windows, and that is the whole list. Put the two together and the doorway is the harder place by a distance: 329 zombies arrive at a doorway across the calendar against 268 at a window, which is 110 per doorway against 38 per window, or 2.9 times the load on each one. Every one of the 8 hordes sends something at a doorway; 6 of them send anything at a window at all, and the first 2 on the calendar send none.

Zombie Siege — 2 of the hordes on the calendar never touch a window. None of them skips the doorways.

The same tier, door against window.
Tier	Door holds out like	Window holds out like	Difference
10% reduction	1222	1222	1.00×
20% reduction	1875	1625	1.15×
50% reduction	4000	3000	1.33×

At the bottom tier the door and the window are the same piece in everything that matters: 1100 hit points, 10% off, the same price on both price columns, and 1.7 min to fit. The window falls behind only above that, by 1.15 times at the middle tier and 1.33 at the top. So the window is the weaker piece at the top of the shelf and the doorway is the heavier place on the map, and the second of those is much the larger effect.

What fitting one actually does

A door and a window are the only two kinds of place in the house the game marks as replacing what is already in them. The house lists 10 kinds of place and Door and Window are the two that swap: fitting a barrier takes out whatever is in the opening rather than standing beside it. So an opening holds exactly one barrier, an upgrade throws the old one away, and there is no such thing as fitting a cheap one now and adding a better one later.

The openings sit in 2 of the 8 rooms. 1st Floor has 2 and Warehouse Interior has 1 of the doorways; 1st Floor has 4 and Warehouse Interior has 3 of the windows. The other rooms have neither, and no purchase adds one.

The defence ring is a different thing again, and it is not a row of openings. It sits outside every room, holds 592 places, and takes the devices rather than barriers. What comes through the door covers what stands on it.

What the Defence ladder actually buys

What each Defence level says it adds, in the game's own words, beside the one figure the level tables carry.
Level	Rank	Fitting time off	What it says it adds
1	Apprentice Defender	5%	Can craft Sandbag and Spike Barrier
2	Skilled Defender	10%	Unlocks Molotov Cocktails. Unlocks proximal defense slots for purchase.
3	Veteran Defender	15%	Unlocks Electric Traps. Unlocks middle defense slots for purchase.
4	Fortification Engineer	20%	Unlocks Mechanical Chainsaws. Unlocks outer defense slots for purchase.
5	Fortress Master	30%	Unlocks Titanium Doors and Bulletproof Windows. Unlocks outermost defense slots for purchase.

The one thing a Defence level carries as a number is the fitting time. It reaches 30% off at level 5, which turns 5.0 min on a Titanium Door into 3.5 min. Getting there costs 7,550 experience; the skills list has how that compares with the other five.

The rest of the ladder’s wording is not a purchase gate in the data. Level 5 says it unlocks the top tier of both openings, and the gate that exists sits on the workbench. The 2 recipes it opens make Titanium Door Package and Bulletproof Window Package, and "Defense level 5" is the only condition either of them carries. The other route to the same package is an order from the Renovation Company, and no level condition reaches it anywhere in the tables. So the ladder gates making one of these, not buying one, and levelling Defence in order to shop is not something this data supports.

The same wording promises rows of defence slots at every level from the second up. The house carries one ring of 592 places with no level attached to any part of it, so treat that half of the text as the game’s advertising rather than as a schedule.

One ending names two of them exactly

Sleepless Defense Line — The Safe House line is the one place in the game where the printed durability is the number that counts, because the check reads hit points and not what gets through.

The Safe House ending is measured on day 71 against 2000 durability on the door and 1500 on the window. Those are hit points as printed, so the comparison the rest of this page makes does not apply to the check: is the only door that reaches its figure and the only window that reaches its own, and every opening has to carry one. On that run the tier question is settled before it is asked.

How the figures on this page are worked out

Effective hit points are a barrier’s hit points divided by the share of damage that still gets through, so a barrier taking half the damage is worth twice its label. How much longer one barrier holds than another is one effective figure over the other. Effective hit points per dollar is that figure over a price, and this page prints it twice because the game carries two prices for the same barrier and they disagree. The load on an opening is every zombie the calendar’s hordes send at that kind of opening, added up across every wave of every one of them, divided by how many places of that kind the house has.

Where this page stops: nothing here is a time to breach. How many attackers reach one opening at once is a matter of how the game paces a wave rather than anything the tables state, so the comparisons are between barriers and not against a clock; what comes through the door carries the damage each kind deals. Repair is not in these figures either, and neither is what a barrier at zero hit points does. Each barrier also carries a bag of its own, 24 cells on a door and 40 on a window, and nothing in the data says what that space is for, so this page does not count it as storage.

What to do

Fit the 3 doorways before either window. They take 2.9 times the load per opening, and 2 of the 8 hordes on the calendar never reach a window at all.
Buy the strongest tier you can, not the best rate. An opening holds one barrier and an upgrade replaces it, so the money you spend on a weaker one is spent again when you swap it. is 3.27 times Reinforced Wooden Door.
Ignore per dollar comparisons on barriers, this page’s included. The list price and the package price rank the six in opposite orders and the data does not say which one you pay.
Do the windows next, in the same order, once the doorways are done. There are 7 of them, which is 2.3 times as many things to pay for.
Fit on a quiet day. Titanium Door is 5.0 min of work, and Defence 5 takes 30% off that and nothing else off the price.
Level Defence for the workbench and the devices, not for the shelf. The gate the data carries is on the recipe; the order from the Renovation Company has no level on it.
If the run is aiming at Safe House, buy Titanium Door and Bulletproof Window for every opening regardless of everything above. The equipment list carries the durability the check reads.

Quick reference

Effective hit points = hit points ÷ the damage that still gets through. That is the number the game does not print.
Strongest door: Titanium Door, 4000, which is 3.27× Reinforced Wooden Door where the label says 1.82×.
Strongest window: Bulletproof Window, 3000.
The openings: 3 doorways and 7 windows, one barrier each, and fitting a new one replaces the old.
The load: 110 zombies per doorway across the calendar against 38 per window.
Per dollar: two prices, opposite rankings, no answer.
Defence 5: 30% off fitting time, and a workbench recipe. Not a shop gate.
Safe House: 2000 and 1500 printed durability, which is Titanium Door and Bulletproof Window.