Interior Guidelines

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All somewhat intact buildings and many other locations in TES III will need interiors. Interiors are created in much the same way as Exteriors, but are generally much more detailed.

Note that interior-making is arguably the easiest entry point into TES III modding.

In addition to reading this page, make sure to also check the editor-specific tips and pitfalls on the Construction Set Tips page!



Like all roles that work primarily in the Construction Set, interior developers need to pass a showcase, before being able to claim interiors on their own. Don't worry, this is not an adversarial process; instead, the showcase is a process where we help you learn the skills and standards needed to make interiors in a way that fits into Project Tamriel and Tamriel Rebuilt.

Showcases should all be posted in the showcase forum (Project Tamriel, Tamriel Rebuilt). You should post exactly one showcase thread, in which you can display however many of the three types of showcase you would like.

Create your showcase with a mod-free version of Morrowind. Project Tamriel and Tamriel Rebuilt only use vanilla Morrowind content (Morrowind, Tribunal, and Bloodmoon) and our own Tamriel_Data assets. If you have a heavily modded game and would like to submit a showcase, it is advisable to work from a fresh install of Morrowind.

A few exceptions for mods that you can use are listed below:

  • MCP (Morrowind Code Patch) – This is not really a mod, but an essential utility required for both playing and developing Tamriel Rebuilt and Project Tamriel. It fixes many critical bugs in the game engine and gives you access to the an enlarged map that shows all of Tamriel Rebuilt (sadly, the latter does not include Project Tamriel yet).
  • Developer Resources – Several vanilla Morrowind items have poorly fitted collision meshes which extend beyond the bounds of the item itself. This means you have to press “F” twice in order for the item to sit properly on top of something else. Tamriel Rebuilt has fixed most of these errors and has provided you with new meshes to use for creating interiors. Simply unzip the file into the Morrowind/Data Files/Meshes folder.

Before posting an interior showcase, please make sure you are familiar with the contents of the rest of this page.


  1. Minimum size is 3x2x2 structural pieces, preferably a 2-story building.
  2. Make sure you pick an exterior building shell to fit, if making a building, or that your cave/tomb would not stick out of the ground (see below).
  3. Use furn_de_p furniture.
  4. Use at least some Tamriel_Data items.
  5. Position/rotate at least 10 items properly on top of the de_p furniture.
  6. Sufficiently clutter the interior. To know how much is enough, see other recent Tamriel Rebuilt or Project Tamriel interiors that are similar to the one you are making.
  7. Include a Northmarker.
  8. Adjust the Interior Cell Settings: Lighting/Water Level/Illegal-to-Sleep-Here appropriately.
    • Obviously, you only need to set the water level if your showcase includes water.
  9. Clean your file.
  10. Your file must include a Path Grid.
  11. All work must be original; do not copy from other interiors!

If your showcase isn't reviewed within a few days, “bump” your showcase or send a message a Lead Developer, on the forum or (better yet) Discord. Sometimes we forget!

Showcase Size

Interior showcases can be either caves or buildings/tombs.

If making a building or tomb, the minimum shell size is 3x2x2 pieces. The requirement for two stories is so that you could learn how to use stairs and ramps. The architecture style of the building does not matter, but it is best to stick to Morrowind architecture styles for a showcase, even if you intend to contribute primarily in Project Tamriel. Furthermore, for the time being, Tamriel Rebuilt is done with the Telvanni and Indoril areas, so Telvanni and Mournhold style interiors are no longer being accepted. The best options for now are either Hlaalu or Velothi. Try to incorporate the stairs into your 3x2 shape, and keep 2nd floors or basements above or below the ground floor, respectively. (See also the tileset-specific rules below.)

If making a cave, make sure to have significant changes in elevation. You must use a minimum of 12 cave pieces for your showcase (see also cave-specific rules below.)

Please do not make really large showcases that go significantly above the sizes listed. These will not be reviewed and you will be asked to make a new, smaller one.

Showcase Furniture (Furn_De_p)

Proper rotation of objects is vital for creating great interiors. That is why it is a requirement for all interior showcases to use furn_de_p furniture. If you look closely, you will notice that objects such as de_p bookshelves and tables are not flat. Therefore, simply placing an object over a de_p surface and “F”ing it down is not acceptable. The item needs to be rotated in order to sit flat on the de_p furniture. We have a good tutorial on object rotation.

You will find this skill very useful in many situations when making interiors – e.g., whenever you have to place items on uneven cave floors, exterior building pieces, or have an item rest on several of its points in a non-standard way.

Note: Tamriel Data adds flat versions of the de_p furniture that start with the ID prefix TR_furn_de_p. You may NOT use them in your showcase! They are fine in regular TR interiors, but not for showcases, for the above reason.

Making an Interior Claim as a Showcase

Making a real claim for a showcase is possible, and will ensure your showcase work will be used. However, it is better for those who already have experience in the Construction Set, and is not recommended for those completely new to the program.

To do this, you can go into the Tamriel Rebuilt Claims Browser and find an unclaimed interior to make as a showcase. You should make a post in the showcases forum with a link to the claim you want, saying that you will use it as a showcase, and upload files to there. Then make a comment on the claims browser page linking to that forum post. The claim will be set to "In Development" as you work on your showcase. If, for some reason, you cannot complete your showcase, you should upload your latest version and say that you cannot work on it. That file will be uploaded to the claim page for someone else to finish.

Interior Claim Workflow

At any point during the making of an interior, you are welcome to ask for help and/or post progress images in Discord. You can also use the comment section of the claims browser, but much fewer people check that.

Getting Started

  1. Find a claim that you want to work on. These can be found in the Tamriel Rebuilt claims browser or the Claims > Interiors subforum of the respective province in Project Tamriel.
  2. Hit the "Claim" button and post a comment on the claim page, asking to claim it. A senior developer will come along a grant it eventually. If you want this to happen faster, also post this on Discord.
  3. Grab the needed files:
    1. The official release of Tamriel Data (our asset repository), which contains the three .bsa files (make sure you register them).
    2. The updated in-development Tamriel Data including the loose files and Tamriel_Data.ESM from GitHub (click on the green Code button, then Download Zip).
    3. The latest version of the province's main .ESM file and the in-development update file.
      • For Tamriel Rebuilt, you can find them on the Release Files tracker. The main file is TR_Mainland.ESM and the update file is TR_Update.esp. On each section file page, the lowermost files on the left-hand-side column are what you need.
      • For Project Tamriel, the main file and update will be on the forums, in the respective provinces' Private > Internal Files forum. You will only be able to access them if you are a Project Tamriel developer.
    4. The section files relevant to the interior (in the same locations as the above).
      • Sometimes, the exterior location for your interior claim is not yet merged into a section file. Then, you will find the exterior claim on the claims browser (Tamriel Rebuilt; Project Tamriel claims are in the respective Claims > Exteriors subforums of the project).
    5. In some cases, the claim page will already contain a work-in-progress file. If so (and unless instructed specifically), use this as a base to work off of.
  4. Set your load order. Note that you should not load the main province .esm file or a section file in the Construction Set when working on your interior claim.
    1. Morrowind.esm
    2. Tribunal.esm
    3. Bloodmoon.esm
    4. Tamriel_Data.esm
    5. Your claim file (.esp)
  5. Check the exterior where your interior will go in the Construction Set to get an understanding of its size. Typically, the needed size will be listed in the claim description as well. This is best to check in another Construction Set window with a different load order. You will have to enable an option in Morrowind.ini for this. For viewing the exterior, append these files to your load order:
    1. [Project Main File].esm – e.g., TR_Mainland.esm for Tamriel Rebuilt, Sky_Main.esm for S:HOTN, or Cyr_Main.esm for P:C
    2. [Update File].esp – e.g., TR_Update.esp for Tamriel Rebuilt, Sky_Update.esp for S:HOTN
    3. [Section File].esp
  6. Read the claim description carefully. All requirements listed there are for a reason, often to not conflict with other claims in the vicinity.
  7. Based on the above, figure out a character for your interior – who lives or works there, what do they do, and how would their place look like. You will have an easier time thinking of furniture and clutter to use in the interior and you will have the opportunity to do some visual storytelling.

Building the Interior

  1. Create a new interior cell. Name it according to the respective project's conventions.
  2. Create the shell in the architecture style specified in the claim. It can help to drag the corresponding building shell (if working on a building interior) to your new interior cell to construct the shell around it. Also add doors and windows.
  3. Add furniture fitting to the wealth and culture of the interior. This will be mentioned in the claim description.
  4. Add clutter on the same basis, taking care to have them flush with the surfaces they rest on.
  5. Add lights. Refrain from using lights that are too high in luminosity, except in special interiors. Instead, prefer a greater number of them dispersed throughout the interior.
  6. Add a Northmarker.
  7. Add a Path Grid.
  8. Set your Interior Cell Settings: lighting, sunlight, fog, water level, "illegal to sleep".
  9. Add NPC markers and/or creatures, based on your planning above.

Note: You do not have to link the outside door to the exterior. This is done later by senior developers when merging your claim into a section file.

Finishing the Claim

  1. Check that you have not gone overboard with the amount of references.
  2. Load your interior in the game (e.g., use the coc console command to teleport there) and see if the interior is traversable to the player. You may have to move some items. This will also help you notice errors that you might not have in the Construction Set.
  3. Clean your file.
  4. Once you are reasonably sure everything is good, upload your file onto the respective claims browser page (you should also be uploading work-in-progress files; it does not matter if these are dirty). To make sure that others understand the claim is ready for review:
    1. set the claim progress to 100%,
    2. press the button that should appear: Put up for Review,
    3. post a comment to this effect on the claim,
    4. notify us on Discord.

This is it! Sometime later, a reviewer will take a look at the interior, fix and document any issues, and post a reviewed file. You may want to check over the changes list for learning purposes.

In some cases, the reviewer will send the interior back to you, when more substantial changes are required. Make any changes requested, and put it back up for review.

General Guidelines

NO Cookie Cutting

Cookie Cutting means copying an existing interior (such as a Bethesda one or any interior from Tamriel Rebuilt or Project Tamriel) or any part of it, and using it as your own. This is NOT acceptable. This does not mean that you cannot look at other interiors to see how items have been used, which items are acceptable within your interior, or even get ideas for your interior. If you see something you like, go to the Object Window in the Construction Set, find the object(s) there and drag it into your own interior.

Note that most of Bethesda's interiors would not pass our interior reviews, so do not simply copy their stuff.


Interiors should be named according to conventions of the different projects under the Project Tamriel and Tamriel Rebuilt umbrellas. The conventions are there to make it easy to find new interiors for reviewers, mergers, and NPCers.

The general scheme is this:

[Project Abbreviation]_[Exterior Claim Acronym]_[Type of Interior]_#

For example, the claim "Lake Andaram 2 Tomb 1" in Tamriel Rebuilt would have the claim name TR_LA2_Tomb_1:

  • TR stands for Tamriel Rebuilt (you would use PC_ or Sky_ for claims in Cyrodiil or Skyrim),
  • LA2 stands for Lake Andaram 2, the name of the exterior claim that has this tomb,
  • Tomb is the type of the interior,
  • 1 is the number in the claim name (the number is dependent on the type).

For cities or some multi-claim dungeons the convention is this:

[Project Abbreviation]_[City Name]_#_[Description]

For example, the claim "Aimrah Interior Claim 2: Sailors' Inn" in Tamriel Rebuilt would be named TR_Aimrah_2_Sailors' Inn (spaces in the city name or interior description remain spaces).

If you have multiple interior cells in your claim, add "_[Description]" to each (optionally not to the main cell). These can be as barebones as TR_LA3_Grotto_1_Upper and TR_LA3_Grotto_1_Lower.

When an interior is merged into a section file, it will initially begin with TR_, Sky_, or PC_, but should be given a proper name after being NPCed.


"Cobbling" means using assets in vastly unintended ways. For example, rotating, combining and bleeding several chairs through a wall in order construct what looks like a bookshelf. Or using Redoran interior architecture pieces on the exterior in order to construct new buildings. Or pasting dozens of small rocks together in order to make a staircase.

Old Tamriel Rebuilt used to rely on these and and many, many other tricks in order to make their interiors and exteriors more varied. This was inevitable in a situation where they couldn't rely on asset developers to produce needed models.

The situation is very different today, and when you cannot do without a specific piece that doesn't exist, do not cobble! Instead, make an asset request on the asset browser, and let the asset developers know on Discord.

Mixing Styles

In Morrowind there are two main styles for interior architecture and clutter: Dunmer style and Imperial style. These should not be mixed, as Bethesda did not mix them. To tell them apart, look at their ID name in the editor. Dunmer objects have 'de' in their name, like furn_de_p_chair. Imperial objects have 'com' in their name, like furn_com_r_table.

Furniture is divided between rich, middle-class, and poor, and should not be mixed either. You can tell which is rich and which is poor by looking at the color of the wood. Generally, the richer the furniture, the darker the wood. You can also read it in the name: _p_ = poor, _r_ = rich, _rm_ = middle class.

Project Tamriel adds its own province-specific assets, with its own ID prefixes; see the guide to Tamriel_Data IDs. These should generally not be mixed between projects and interiors as well. A common error is to use containers from other provinces; stick to containers starting with the ID T_Mw for Tamriel Rebuilt, T_Cyr for Cyrodiil, and T_Sky for Skyrim.

There are some exceptions where mixing items from across the provinces is allowed – generally near the borders of provinces or where there is a character or institution specifically involved in trade or diplomacy with another province. These situations need to be carefully considered and instructions on mixing will be given in claim descriptions.

Fitting the Exterior

Most of the Hlaalu exterior cells (some new ones have been crated in Tamriel_Data since this image was taken). A Hlaalu interior must fit one of these in terms of shape and size.

While magicka does exist in Tamriel, it is important to make sure that if your interior has an exterior shell, it fits! If your exterior has a little square building, don't create a star-shaped interior for that building!

It is best to copy the exterior shell to your interior cell so you could compare if the size and shape matches. Also, make sure to take a look at the specific exterior where your claim will go. If the building is built into a cliff, you will have more space. You may also have more space in your basement level.

There are some exceptions to the exterior matching rule due to asset limitations and Vanilla conventions – check the Tileset-Specific Rules.

Note: Interior tiles are bigger than exterior tiles; this relatively small discrepancy in size is considered OK.

Grid Snap

Grid snap is an essential part of constructing interiors from scratch.

To set up grid snap in the CS, select the menu option File > Preferences. In here you can set the Grid Snap size, Angle Snap size, and enable grid and angle snapping. You can also turn grid snap on/off by pressing the 6th toolbar button, the one with 4 horizontal and 4 vertical lines.

Typical grid snap values are 64 or 32. Only use lower if the set absolutely necessitates it (in some specific cases, sets might not fit together at 32, so you may go down to 32, 16, or even 8), but generally keep your grid snap values a these two. It makes it unnecessarily difficult for future reviewers or section editors to change things if needed when they have to fiddle around with their grid snap to find what the claimant used because it’s not 64 or 32.

You may end up accidentally nudging a shell piece off grid during the cluttering stage. If you notice this later, you can still fix this:

  • In the vanilla Construction Set, selecting the shell piece first, then select all items that were placed into that shell piece. Turn on grid snap and move the piece back on the grid.
  • In the Construction Set Extender (CSSE), do the same, but select the shell piece last.

Floaters and Bleeders

A "floater" is an item that hangs in the air without any supports, whereas a "bleeder" is one that intersects the geometry of another item. These mistakes are common to make when placing items in the Construction Set.

However, we are pretty strict about avoiding such mistakes. Most items should rest perfectly flat against each other (some exceptions are sacks and clothing bleeding, see below).

In order to check to see if items are sitting flat on each other, left click the item sitting on top of the other item. You will see the selection box, composed of red, green, and blue lines. Where the two items meet, you should see 4 lines that make up a rectangle, usually the red and green lines. These 4 lines should appear as dotted or dashed or sometimes they will flicker on and off as you rotate the view. This usually indicates that the item is sitting perfectly flat on the other item. If the lines are solid then the selected item is most likely floating. If the lines are missing, then the selected item is most likely bleeding. If some of the lines are missing and others solid, then the selected item needs to be rotated more.

Rarely, an asset will have a selection box that does not match its geometry. If the selection box looks right but the object is obviously floating then ignore the box and put the object on the floor as best as you can. Only do this if the object is obviously not on the floor; most of the time this will not be a problem.

Reference Count

For performance reasons, we try to keep single-cell references in interiors below 800 (900 is already exceptional; 1000 is the absolute hard cap). If you cannot go lower than that, you will have to split your interior into multiple cell.

Note that 800 references is a limit, not a target. Do not add extra clutter because you feel you have to get closer to that figure; most cells should be well under it.

Unique and Quest Items

Unique items and quest items should not appear in your interiors (unless you created them yourself). Most unique items have ID names that end with “_unique”, “ _uni”, or “_u”. If you are unsure the item is unique, load the main province .esm file (e.g., TR_Mainland.esm for Tamriel Rebuilt) and your section file, then check the Count column in the Object Window. If only 1 has been used, the item is probably unique. You can also right click on the object and select "Info" to see where it is used, and if those locations are similar to your showcase interior.

That being said, you are free to create new items in your claims, if you feel they fit. Adding a new weapon with a new or old enchantment is fine. However, when you create the new item, be sure the ID name starts with the proper province prefix (e.g., “TR_” for Tamriel Rebuilt).

Scaling Items

Items that can be picked up should not be scaled (miscellaneous items, armor, weapons, potions, ingredients, etc.)! This is because if the player picks them up and places them back down, their scale will be reset to 1, which can be very jarring.

Other items, such as statics and containers, can be scaled, but only within reasonable bounds.

For containers specifically, use these rules:

  • Crates, barrels, vases, and chests: do not rescale. These are implied to be produced in quite standardized ways and it doesn't make sense to have them in all different scales.
  • Furniture: okay to rescale to a minimum of 0.9.
  • Baskets and urns – okay to rescale between 0.9 and 1.1.
  • Sacks: okay to rescale to a minimum of 0.75. We have dedicated small sacks, if you need smaller ones.
  • Flora – okay to rescale.


The Northmarker is a static that is used by the game to correctly orient the map. A good place to put the Northmarker is just outside the main entrance door to your interior.

To calculate the rotation of the Northmarker, you will need to find the Z rotation values of both the exterior and interior load door in the object properties. You can then calculate the rotation of the door thus:

northmarker = (((360 - exterior_door_z) % 360) + ((interior_door_z + 180) % 360)) % 360

It is probably easiest to use the Discord bot developed by Worsas, which is present both in the Tamriel Rebuilt and Project Tamriel servers. To invoke the bot, type in any channel:

!northmarker <exterior_door_z> <interior_door_z>

Replace <exterior_door_z> and <interior_door_z> with the values for your doors.

Note, however, that for some doors, like the Hlaalu load doors, the rotations are set up differently and the above formula (and the Discord bot) may not be able to produce accurate results. Usually, these will be off by 90 degrees.

Always check whether the calculated Northmarker is correct – view your interior from top-down and rotate your viewport so that the Northmarker is facing up. On a different Construction Set screen, open the exterior claim containing the entrance to your interior, select it, and press T (you will have to have set a Morrowind.ini setting to be able to do this). Do the orientations of the exterior and interior doors align?

Interior Cell Settings


You must adjust Light Settings in your showcase interior through the main menu in the Construction Set. Select “World > Interior Cell...”. Scroll through the Cell Descriptions to find your cell. Now adjust the Ambient, Sunlight, and Fog settings. Find an Ambient color that fits the style of the interior – take a look at similar interiors in Tamriel Rebuilt or Project Tamriel, but do not copy the settings exactly.

Keep Sunlight low – our interiors as a rule have values between 10-20 for Sunlight.

"Illegal To Sleep Here"

Be sure to check the "Illegal To Sleep Here" box if the location is privately and legally owned.

Water Level

If your interior has water, the Interior Cell Settings is also where you adjust the height of the water.


Greenlight can be seen on the Mazte bottle next to the lamp. It occurs because the bottle is placed too close to the lamp.
Greenlight is present on the chair at the bottom of the image, circled in red.

Greenlight is a bug that occurs in the Vanilla game engine due to inaccuracies in rendering lights. It appears as a strange greenish-yellow hue on items close to a light source. This effect can be difficult to notice for a newcomer; see the images to the side.

Generally, greenlight occurs because an object is too close to a light, but it is not always possible to predict which situations cause greenlight.

Our convention is to notice this effect and to remedy it, whenever possible. Make sure to take a look through your interior with that in mind and move objects until the effect is reduced.

Asset-Specific Rules


Like the tileset and furniture, the type of tableware you use should be an indication of the culture and wealth of the interior.

Tableware in Morrowind

  • You-Need-Permission-To-Use-This Class: Ebonyware
  • Very Rich Class: Fine Glassware (Purple glass)
  • Upper Class: Blueware, Goblets
  • Middle Class: Greenware, Yellowware, Redware, Peach glass, Common Plates
  • Lower Class: Wood, Clay, Stoneware, Redware, Vanilla Tankards

A lower class interior may, however, have a piece or two of higher class tableware, e.g., a piece of Greenware.

Sacks, Pillows and Cushions

Sacks are made of an easily deformed, burlap-like material (probably wickwheat in Morrowind). So, bleed sacks into the objects that they rest on to make them look more natural. The same idea applies for pillows. Cushions, on the other hand, should not bleed into anything, nor anything into them (except sacks and pillows).


Clothing is very similar to sacks and pillows, as mentioned above. So you are allowed to bleed clothing into the object it sits upon.

However, most clothing is not textured on the bottom. You must make sure that part is not visible from any angle. The easiest way to achieve this is to F-drop it a second time

Note: Morrowind Optimization Patch adds backsides to clothing meshes, but we cannot assume that players are using it.


Rugs are allowed to bleed into the floor (especially the really thick ones), and the ones with tassels on two sides should be bled to make the tassels just barely float.

However, items placed on a rug are not allowed to bleed into the rug. And items that are partially on a rug must be rotated slightly to still have all legs resting on both the rug and the floor.

You will save yourself a lot of effort if you simply have pieces of furniture either totally on or totally off a rug.


In Hlaalu interiors in Tamriel Rebuilt, tapestries must be hung in a particular manner. Try to keep the tapestry centered with regards to the wall shell piece. Pay attention to the wooden pole that attaches to the wall – do not bleed it into the horizontal wooden pole that runs under the ceiling, but rather into the plaster above it. Make sure that the ropes do not bleed into the ceiling. See the image to the side.

Pointy Bottom Bowls

These bowls are a real headache for most people. We ask that you to, first, rotate the bowl so that the selection box lies perfectly flat on the underlying surface. Then you can lower (aka bleed) the bowl into the underlying surface. How much to bleed is up to you, but it must be consistent throughout the interior. Just be sure to check inside the bowl afterwards and make sure the underlying surface does not show through the bottom of the bowl.

Food, Ingredients, and Drinks

Pay close attention to which food and ingredient items you are using. Food especially doesn't travel well. By far most of them should be native to the province you are modding for, unless you mean to specifically highlight trade ties to some other province.

Drinks can travel a little further; still, most provinces have only a select beverages that you'd expect to commonly find over Tamriel. And even so, mixing too many province-specific assets into other provinces can make the world seem small.

Drinks and foods can also have wealth connotations. For example, Llotham is a non-alcoholic drink for labourers in Morrowind. It is mostly a thing in Indoril lands, but can be found elsewhere as well. Goya is, instead, a fancy drink for nobles and should be found only sparingly in mostly wealthy interiors.


  • Book placement should have some thought put into it. Not every book fits in every interior. If you need help figuring out whether a book fits, ask on Discord.
    • A common offender is a A Brief History of the Empire. Do not place it in an interior unless there is a good reason to have it (like a scholarly or political context). The books have previously been massively overused in Tamriel Rebuilt.
    • Don't feel the need to exhaust every possible relevant book for a particular location's theme. Remember that the player should not find every book on magic in every mages guild, for example.
  • The vast majority of residential interiors should get no more than 1-3 common books.
  • Outside of book stores or libraries, avoid putting a complete series of books, e.g., all four A Brief History of the Empire books, in one interior.
  • That said, some locations, like libraries, guild halls, and booksellers, should get a lot of books. However, do not copy and paste books to fill shelves! Books are content, not decoration, and there's generally no reason why a player would ever need two copies of one book.
    • That said, acceptable exceptions are books in bookstores or libraries that are explicitly meant to be widely circulated work and/or a work that's very significant to the location it's in. E.g., you might put four Cantatas of Vivec on a shelf in a major Temple library. Even then, at least place them slightly differently to one another, see the next point.
  • Books should not be placed perfectly aligned on their shelves. In order to fill space on shelves and maintain visual interest, books should be tilted against each other, placed at different "depths" in the shelf, divided by bookends and other similar sized objects that match the theme of the interior, or stacked flat. A nice looking bookshelf should look like it's in active use.
  • For skill books, keep in mind that the average interior does not need to have any! Only the exceptional one should have more than one and even large libraries shouldn't have too many. If you are placing one, make sure that:
    • the same skill book is not also present in a nearby location,
    • the owner NPC is themselves skilled in the skill being taught (i.e., is a trainer or someone with extra interesting characterization).

Tileset-Specific Rules

Different tilesets (i.e., architecture sets) come with specific conventions in vanilla Morrowind and across Project Tamriel and Tamriel Rebuilt. Make sure you stick to these in your claims.


Except for mud and snow caves, treat all cave surfaces as though they are solid rock.

Typical miscellaneous/static/container objects should not bleed into the floor or wall of a cave. The exceptions are beams, ramps, platforms, and large structural elements. These should bleed into the rocks (in particular the support beams). Be sure to notice that the in_cavern_ramp(s), ex_de_docks_(s), and ex_common_plat_(s) do not have level boards and items placed on them may need to be rotated slightly to sit properly.

Specific to Tamriel Rebuilt, different cave tilesets from Vanilla Morrowind tend to have different associations, which we should stick to unless for good reasons:

  • Grottos always use mudcave.
  • Dwemer ruin caves always use mudcave.
  • Telvanni tower caves always use pycave.
  • Egg mines mostly use moldcave, with thee exceptions (out of 32) — two pycave and one pycave-lavacave mix.
  • Mineral mines mostly use moldcave, with three exceptions (out of 12) — two pycave and one mudcave.
  • There is only one Ashlander burial site (Urshilaku), and it uses moldcave.
  • Strongholds mostly use mudcave (Berandas, Indoranyon, Telasero, parts of Kogoruhn), with two exceptions (Rotheran uses moldcave, Kogoruhn has some lavacave).
  • Bonecave is only used once (Mamaea, a Sixth House base).
  • Daedric sites, including caves occupied by Daedra as well as shrines, mostly use lavacave, but use pycave instead about a third of the time. They never use moldcave or mudcave.

Hlaalu Buildings

See the guide here:

Com (Imperial) Buildings

The exteriors of Com (Imperial) Buildings mentioned here.

The exteriors of the Com set are infamously small. Hence, our standards are to enlarge the interiors in predetermined ways:

  • ex_common_house_tall_01 and ex_common_house_tall_02 – look like they should be 2x2, but need to be 3x3 to make them fit anything worthwhile (occasional 2x2 exceptions for intentionally cramped interiors).
  • ex_common_house_tall_02 – should be 3x4 on the top floor because of the overhang.
  • ex_common_building_01 – exterior shells should be scaled up to 1.25x when possible. Even at that scale, the "correct" fit would be very tight, so interiors should exceed the scaled shell by a bit more to make the interior 2x3 on the short side and 2x4 on the long side.
  • ex_common_building_02 – would only "fit" at 2.5x2.5. To avoid every one of these interiors being a cobbled mess, they have been standardized at 2x3 (occasional 2x2 exceptions for intentionally cramped interiors).
  • ex_common_building_03 – these shells fit rather perfectly over 2x3 interiors, but Vanilla makes them 3x3 (or sometimes even 4x4). We should instead make them 2x3, given we have now S'wit's stackable stairs that allow for this.
  • ex_common_tavern_01 – to comply with Vanilla standard and to be able to fit a real tavern, make these interiors 4x4, and leave a notch at ground level for the door.

Chimer Strongholds

See the guide here:

Daedric Ruins

See the guide here:

Velothi Towers

See the guide here:

Path Grids

A good example of a Path Grid in the cavern of Addamasartus, near Seyda Neen. The grid follows the ledge leading to the entrance. Without this grid, the smuggler would get stuck behind the ledge; with it, she knows to go up it from the side.

All interiors must have Path Grids (except for those parts underwater), which help the NPCs navigate. This is especially crucial on the vanilla engine, but OpenMW benefits from this, too. Pathways and path nodes are especially useful at places where the AI has trouble navigating. A flat, large, straight hallway without obstacles is not even strictly necessary (add one in any case), but a place with stairs, door jambs, ramps, and other obstacles will need a detailed grid.

It is the job of the interior maker to add a Path Grid. This is simple (tutorial originally by Gez):

  1. Construction Set toolbar button for opening the Path Grid editing window.
    Press the Path Grid Editing icon on the Construction Set toolbar or use the menu option World > Edit Cell Path Grid.
  2. Path Grid editing window. You do not need to set any of the settings here; just press the Save button after finishing your Path Grid in the Render window.
    This will bring up a small window with options, none of which you need to set:
    • The generate default grid option should not be used, as the algorithm for generating it is not particularly smart.
    • Granularity defines the size of the squares created by the generated Path Grid, and as such, there is no need to change it.
    • Save user points toggles whether manually placed nodes are preserved when automatically generating a (new) Path Grid. When unchecked, all nodes are deleted prior to generation; when checked, the blue ones stay and only the red ones are deleted.
  3. Path Grid nodes. Use Right Click to create them in the Render window, Left Click and drag to move, and Ctrl + Left Click to link the nodes.
    Leave the Path Grid window open and go the Render window, where you can add your path nodes according to the below rules:
    • Right Click creates a new path node.
    • Path nodes can be selected and moved just like any other items. However, they cannot be rotated. (That would be useless anyway.)
    • Path nodes can be deleted just like items, with the delete key.
    • Default (auto-generated) path nodes are red, custom path nodes are blue. Moving a red node turns it to blue.
    • When in Path Grid mode, it is the selected node that is used as the pivot point when rotating or centering the view.
    • With a node selected, Ctrl + Left Click on another connects both, or if they are already connected, disconnects them.
  4. When adding the nodes, ensure the following:
    • The paths between your nodes should not be obstructed by items.
    • Do not place too many nodes. Generally, you should strive to have three or four nodes per room, although you may need more in large rooms or ones with complex geometry. Look at other recently reviewed interiors to see how dense a Path Grid ought to be.
  5. Finally, once you have made the Path Grid for your cell, click on Save in the Path Grid window. This saves your Path Grid and closes the Path Grid window, returning the Render window to its usual mode.

Cleaning Your File

While working in the CS, you will inevitably modify something that you had no intention of modifying. This may be static, miscellaneous object, or another cell. It is important that these minor changes do not appear in your interior file. A file with such modifications is called “dirty”, and needs to be “cleaned” before submission.

There are two acceptable ways to clean your file – with the TES Advanced Mod Editor (TESAME) or with the Construction Set.

Cleaning with TESAME

Delete everything from your plugin except the following: TES3, any object you made yourself (such as a note), any cell you created/modified, and the corresponding Path Grid. See the TESAME instructions for more information.

Cleaning with the Construction Set

Start the Construction Set and select the menu option File > Data Files, as if you were going to load your file. Select the relevant masters and set your file as the Active File, but instead of pressing OK, press the Details... button. You are shown a list of records in your file. Highlight the items you would like to delete and press the DEL key on your keyboard. (Don't select any REFR records under your CELL – these are the objects you added.) Click Yes on the Mark As Ignored window to prevent the Construction Set from loading these records. Close the File Details window, and now click OK in the Data Files window to load your file without the ignored records. Save your cleaned file using a new name, just to be on the safe side.

Other Resources