No matter how many times I take a break from and then return to Terraria, one fact remains constant – I simply can’t remember how to build suitable NPC houses.
I’ll remember that they need things like a background wall after my first attempt, niceties like a work bench and a torch after being told again that my housing isn’t valid, a chair on my third try, and then someone will finally tell me the shoebox I built is just too small to be habitable before I’m done.
So what counts as valid housing in Terraria?
A valid house in Terraria must be 60-750 tiles in total area, include a frame that completely encloses the interior from all 8 directions, and must have a flat surface item, a comfort item, and a light source within. Additionally, no wall holes greater than 4 tiles wide or tall are permitted inside, most background walls must be placed by a player to be valid, it cannot have an evil score of 50 or more, and it cannot have a home tile score lower than 1.
Wow, those Terraria NPCs sure are picky about the houses we’re building for them! There are a ton of rules to remember when building houses for them, so let’s take a look at their requirements one at a time to make sure we don’t miss anything.
Why Does it Say This is Not Valid Housing in Terraria?
This isn’t always an easy answer to run down, as in-game messages like “This is not valid housing” aren’t especially descriptive. While current versions of Terraria will actually tell you one thing your house is missing nowadays, those playing on older consoles that aren’t receiving new updates will need to do some detective work to see what their houses are missing.
Fortunately, we have a checklist you can quickly run through that will help you turn an unsuitable house into one that is at least tolerable for your NPCs.
Your House Must Be 60-750 Tiles in Size
The size of your house should be the very first thing you decide on, especially if you’re picky about how it looks. While most who start their Terraria journey are completely fine with the idea of building tiny houses for quick construction and minimal strain on your limited materials, your NPCs require at least 60 square tiles worth of house to be happy homeowners.
If you’re building a rectangular house, there are several configurations that easily accommodate this minimum area mathematically, including:
- 5 x 12
- 6 x 10
- 7 x 9
- 8 x 8
Whichever of these numbers you use for the width or the height doesn’t matter, and you can certainly make your houses bigger, as long as the exterior doesn’t exceed 750 tiles in size. Houses also don’t have to be rectangular, so feel free to experiment when designing them!
Remember that you will need to leave enough room for an NPC to stand in their house and to set up a work bench plus a chair to satisfy the minimum furniture requirements, so make sure you have at least 3 tiles of interior height and width somewhere within your house to accommodate these needs.
The Interior of Your House Must Be Fully Enclosed
This requirement usually doesn’t trip people up – you’re just double checking that the exterior frame of your house is solid and it has completely enclosed the interior. Solid means that you’re using the following types of items for your outside walls:
- Blocks (non-actuated if you’re playing around with the Actuator sold by the Mechanic)
- Platforms (non-actuated if you’re playing around with the Actuator sold by the Mechanic)
- Trap Doors
- Tall Gates
Yes, this means if you don’t want to be slowed down by doors, you can in fact build most of your exterior walls out of platforms, as platforms also count as an entry to the house. It also means your houses can be made of anything from dirt blocks to platinum bricks; you can throw as much or little money at construction as you see fit.
You must also have at least 1 solid non-platform tile on the floor of your house, as without it, you won’t pass your home tile score test later on. If you’re building connected NPC houses, multiple houses can also share the same exterior wall.
An enclosed house interior simply has no tiles inside the house that connect directly to a tile outside the house – including diagonally. You literally can’t cut corners on your construction in Terraria, otherwise your housing won’t be accepted.
Your NPC Houses Must Be Furnished
In a world with crafting capability that would make Ikea jealous, it’s a little infuriating that your NPCs can’t be bothered to furnish their own homes. On the bright side, furnishing an NPC house really isn’t difficult – all you need to do is include at least 1 each of the following items: An entry, a light source, a comfort item, and a flat-surface item.
Any item or variation of it in a furnishing requirement’s list will fulfill that requirement, so pick whichever one(s) you want!
- Tall Gate
- Trap Door
- Christmas Light
- Hanging Brazier
- Heart Lantern
- Jack ‘O Lantern
- Jellyfish Jar
- Lamp Post
- Peace Candle
- Skull Lantern
- Star in a Bottle
- Tiki Torch
- Water Candle
- Bar Stool
- Chippy’s Couch
- Picnic Table**
- Alchemy Table
- Bewitching Table
- Picnic Table**
- Work Bench
- War Table
* You don’t actually need to create an entryway large enough for an NPC to get in or out of their home – a single Platform will cover your entry requirement.
** The Picnic Table is especially useful for NPC house construction, as it counts as both a comfort item and a flat-surface item.
Don’t Leave Large Holes in Your Walls
Holes in your house’s interior walls must be no larger than 4 tiles wide or tall in order for the house to be considered suitable, which is actually… really big, as seen above. If you’re really anti-wall, you can have multiple holes up to 4 x 4 in size, which would let you knock out most of the interior walls in my example above without any problems arising.
Except for monsters being able to spawn in your house. But that’s really not your problem, now is it?
You Need to Place Your Own Background Walls
This requirement is extremely straightforward, and only comes up as an issue if you’re trying to use naturally occurring walls to cover a housing requirement. That said, there are a few naturally occurring walls you are allowed to use if you’re so inclined:
- Disc walls (found on Floating Islands)
- Dirt walls (if you or another player places them)
- Living Wood walls (found in Living Trees)
- Planked walls (found in Underground Cabins)
- Sandstone Brick walls (found in Pyramids)
If the walls you found naturally in the wild aren’t in this list, you’ll need to take them down and either set them up again or replace them with something else.
You’ll also want to be careful if you’re using Stone walls near biomes that spread like the Hallow or the Crimson – if a biome converts your walls into Pearlstone, Ebonstone, or Crimstone walls, your house will no longer be considered valid.
Your House’s Evil Score Must Be Less than 50
In Terraria, a house’s evil score is determined by the tiles near its highest, lowest, leftmost, and rightmost blocks. While this number can vary depending on the version you’re playing, it is currently 45 tiles to the left and right, and 43 tiles up and down.
The following blocks and items can impact your house’s Evil Score:
+1 Point each
- Corrupt/Crimson grass
- Corruption/Crimson thorny bushes
- Corruption plants
- Ebonsand/Crimsand blocks
- Ebonsandstone/Crimsandstone blocks
- Ebonstone/Crimstone blocks
- Hardened Ebonsand/Hardened Crimstone blocks
- Purple/Red Ice blocks
- Vile Mushrooms
-1 Point each
- Hallowed grass
- Short Hallowed plants
- Tall Hallowed plants
- Pearlsand blocks
- Pearlsandstone blocks
- Pearlstone blocks
- Hardened Pearlsand blocks
- Pink Ice blocks
- Sunflowers (-40 points each)
Add everything together and you have your house’s evil score. If it’s 50 or more, the message “This housing is corrupted” will display when checking its validity. If it’s 300 or greater, you’ll get the helpful “This is not valid housing” message.
If you house’s evil score is less than 50 and you aren’t building near or with materials from the Corruption or Crimson, you should now have a valid house! For those building more dangerously, you’re down to the final hurdle, the home tile score.
Note: The Truffle NPC requires 100 Glowing Mushroom biome blocks in the area surrounding your house, and counts those within the same area used to calculate your evil score.
Your Home Tile Score Must Be Greater Than 0
Remember that non-platform tile I said you needed on your house’s floor when you were enclosing your house? It’s now time to talk about why we need it.
The home tile score is calculated using a pair of formulas, and its purpose is to determine where an NPC will initially stand in your house. Generally, the only ways you’ll fail this requirement are by either having platforms make up the entirety of your house’s floor or by building too close to a lot of Crimson or Corruption tiles.
We’ll get to the math Terraria uses to calculate this value in a moment, but first we need to cover the requirements for a home tile.
A home tile must:
- Be a solid tile (the purple tile in the diagram)
- Be between 2 solid, unactuated tiles (the blue tiles)
- Not be actuated
- Not be a Platform or Bubble (though the tiles next to it may be if so desired)
- Not have objects that block entities from passing through in a 3×3 square directly above it (the yellow tiles in the green square)
- Not have valid foreground blocks (like furniture) or solid tiles in the 3 tiles directly above it (the green square)
- The 3 tiles must also be within the house
Now it’s math time. We’re going start with a score equal to 50 – your evil score. From there, we’re going to look at the red and white blocks and make the following additions and subtractions:
- -20 points for each tile occupied by the spaces that would be used by a Door when closed or a closed Tall Gate
- -5 points for each unactuated solid tile
- +5 points for each tile occupied by other objects (exempting most plants and torches)
For tall, narrow houses (5 tiles wide), you’ll usually be down 50 points between walls and a standard door, so you’ll be relying on at least a piece of furniture to keep you above 0 if you have no evil score. Wider houses will suffer fewer penalties, though particularly thin or short houses will still be penalized approximately 20 points.
Fortunately, you only need to be above 0 in order to move on to the final calculations for your home tile score:
- If you’re assigning a 2nd NPC to your house (usually a town pet), and their current tile is less than 3 tiles from your existing NPC’s home, set your home tile score to 1.
- -30 points for each Chest in any part of the 5 x 4 tile area above your home tile. This cannot reduce your score below 1.
- +15 points for each valid tile above your home tile (denoted in yellow in the diagram)
If your final score is greater than 0, your housing is now suitable! In the event you have multiple eligible home tiles within your house, your NPC’s banner will hang above the one with the highest score. If there is a tie, banners will hang over the leftmost home tile tying for the highest score in your house.
Cool Terraria House Designs
With enough time and dedication, you can build a ton of unique, robust houses for your NPCs and bases of operation for your own needs. You’ve seen a couple I’ve put together in this article, but here are a few other examples to help you get ideas for your Terraria dream house!
Click any of the pictures to enlarge.
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Braden is a founder of Assorted Meeples and has been a gamer & writer with a vivid imagination all his life. Don’t believe us? Check out his excitement when meeting Goosebumps author R.L. Stine as a kid! An avid Magic: The Gathering spellslinger for over 15 years, you can always convince him to shuffle up for a game (or three!) of Commander.