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Skyrim Mod Use: In-Depth
By KaZumaKat
This is an in-depth guide to the information the avid modder of Skyrim should know, ranging from important topics such as load order, to the commonly used community tools and others. If you're intending to branch out and explore a more modded Skyrim, this is your guide to help you keep your sanity in case things go horribly wrong, and hopefully to prevent the horribly wrong from happening.
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Introduction: What this guide contains, and what you can expect.
Hello and welcome to my guide. This guide is meant for the mod user who wishes to learn more about modding, proper preventative action and reaction to avoid any myriad of issues arising from mod use, and other information that will prove important as you learn how to mod Skyrim the way you want it to be. This is not, however, a tutorial on how to use the Creation Kit, as there are several guides and tutorials for that specific topic on its own.

This is a guide for those who have had a taste of modding their Skyrim, and want to go a level deeper, with more mods, and wishes to have them work as seamlessly as possible to the betterment of their own enjoyment of the game.

Do be warned, this guide is heavy on words, and light on shinies. However, the information contained herein has saved many a friend of massive headaches with mods as your savegame, Skyrim, and your mod list grows.

So, on to the meat and bones...

EDIT: There is a new section at the very bottom of my guide pertaining to the released Legendary patch for those who are worried about mod incompatibility with it. It will be actively edited as more information reaches me and I can edit the guide accordingly.

EDIT 2: There is a new section below the Legendary patch information regarding heavy mod usage and the Skyrim Gamebryo engine running to a just-discovered memory limit. This section is brand-new and has information that is as complete as the community knows on the current subject. This section should be read by those who use texture replacers and the like.
I. YSKT, You Should Know This
So, to cut straight to one of the common questions many mod power users like myself have to answer to the new PC Dovahkiin that join our ranks is "can Steam Workshop mods and Skyrim Nexus[skyrim.nexusmods.com] mods work together?".

The answer is: YES.

In fact, the official DLC's for Skyrim, namely:
Dawnguard

Hearthfire

Dragonborn

They are all architecturally "seen" by the Skyrim game engine as mods themselves.

You may ask yourself, "how-what? What is this magicka?!".

Well, thats also how the main data file for the official patches also get loaded into the Skyrim game engine every time you pull the game up to play. They are treated as additional data files the engine must read, and then load into the game. Its just that the data file itself, named as "Update.esm" is treated a little differently because of its nature, and is programmed into the game engine as so.

So what does this mean to you, the everyday mod-user? Bethesda's updates and DLC's are treated with the same, or similar, respect as mods you get from either the Steam Workshop, or Skyrim Nexus. Keep this in mind, as it wll become vitally important in the next section.

Next, you may have already heard about, or are already using, a mod manager to handle the many myriad of mods you are using, and/or intend to use. It is vitally important you get familiar with your chosen mod manager, and learn to properly identify, categorize, and sort your mods. There are currently two publicly known mod managers out there. One is the vernerable, and easy-to-use Nexus Mod Manager, a product of nearly a decade's worth of effort and evolution undergone by the burgeoning modding community that plays, supports, and even expands Bethesda's offerings all the way from The Elder Scrolls III: Morrowind.

Nexus Mod Manager[skyrim.nexusmods.com], which supports games from Morrowind to Skyrim, and all in-between.
*video by Gopher of Fallout 3, Fallout New Vegas, and Skyrim modding fame, from his channel, GophersVids*

The other, more techically-inclined, yet far more venerably powerful mod managing tool is Wrye Bash[wryemusings.com], which is a highly-advanced tool that is famous for its ability to create "bashed patches", which are, as the name implies, bashed-together data records of your mods to allow more seamless integration between them. All the information regarding this tool is all in their website. Just be advised, usage of Wrye Bash is usually reserved for extreme mod usage, and is only useful for advanced mod users which require heavy intercompatibility between vastly different mods.

In nearly all cases, the Nexus Mod Manager[skyrim.nexusmods.com] is more than enough for your needs.

Now that you know a little more about mod managers, on to why they're so important.
II. LOY, Load Order and You!
Load order. Why is load order important?

Well, in the simplest of terms, they decide the hierarchy and priority of what you load into the game engine. Remember what I said about the DLC's?

Basically, it works like this: anything that loads later, or lower in the list, is loaded last. This means that having a mod that does something, then another mod that changes that something, must be loaded in that order, and not another way.

An example:

If we have a mod that adds, say, a magic sword of dragonslaying (lets call it Mod A), then another mod that changes that specific sword to a two-handed version (thereby requiring Mod A, lets call this Mod B), they should be loaded in that order.

The most common Crash-To-Desktop (CTD) problems most first-time mod-users face is usually load-order-related. To create a guaranteed CTD using the example above, Mod B is higher in the load order than Mod A.

You see the problem here? The Skyrim game engine will read your load list and see a mod that references something it doesnt know yet, gets massively confused, and crashes.

This is a simple example. Now complicate matters with the many myriad of data records that are used for Skyrim, the interaction between them, large and small mods that cover several different facets of the game and can "collide", and you can see the extreme importance of load order.

So, how do you solve this problem? How do you know which mod should load higher than the next? Simple, you dont really need to. There is a tool for that.

Enter BOSS[skyrim.nexusmods.com], which stands for Better Oblivion Sorting Software[skyrim.nexusmods.com]. This is actually a product of experience by modmakers with the precursor of the Skyrim game engine used in Oblivion, and additional experience with it as the same engine was used for Fallout 3, Fallout New Vegas, and the now-upgraded one for Skyrim. This community-authored and -maintained tool automatically sorts your load order in the most efficient, most compatible and most stable way it knows how to, based upon a master list of known mods from its Google repository.

Gopher himself has released a video on the same topic, only using TES5Edit to troubleshoot load-order issues, and is another method to try:

Of course there are some mods that BOSS does not recognize. This is where you must refer to the mod's readme or documentation for load order instructions. If there are none, dead-reckon it by finding similar mods and sort it right underneath them. A common occurence of this is brand-new armor or weapon mods. Just make sure to set them (via your chosen mod manager) to be in the list just underneath your similar mods.

Now what about the mod files themselves?
III. BSA's, ESM's, ESP's, Loose Files, and TES5Edit
You may be, at this point, looking inside the Skyrim /Data/ folder and noticed all the subdirectories, the files ending in .BSA, .ESM and .ESP and be wondering, "what is all this?"

Well, I'll tell you, in a short nutshell. Trust me, when I first started out with this game engine waaay back in Oblivion, we didnt have the nice tools and the Nexus network, the Steam Workshop, and all the other places to help us mod our game. Most of this for me is learned via dead-reckoning, many destroyed game-saves, many fresh un/reinstalls of the game itself, and the like. This info is here so you dont have to go through the horror I have had to go through learning all this back in the day.

A .BSA file is a Bethesda Softworks Archive, usually contains all the hard data for the game itself, ranging from all the sights, sounds, animations, and stuff that you immediately see in the game world. Good examples of data that's contained in the many .BSA files are the voices, textures, model/meshes, interface, animation, etc. Large mesh/texture addition/replacer mods may also be released with a .BSA file for file size and/or other issues and is handled relatively seamlessly by the Skyrim game engine. This is usually loaded first by the game engine, as it needs to have the stuff to work with before .ESM's and .ESP's come into play.

An .ESM file is a master data file that contains data entries for all the things in the game. This is where you will find all the data records for the game, ranging from quest records, cell records (location/environment/scenery data), weather records, NPC data, weapon, armor, and item records, and the like. Seldom will you find a mod that uses an .ESM file, and oftentimes, it is an .ESM for good reason. Most mods like this are not uploadable to the Steam Workshop mainly because of the Creation Kit unable to save in .ESM format, thus not being uploadable to the Workshop (unless this has changed recently). The Skyrim game engine places priority in an .ESM's data records, until modified by an .ESP (but an issue can arise with this, more later). .ESM's by their importance and nature are loaded first by the game engine, no exceptions unless the ESM's must be in a specific load order (like Skyrim.ESM loading before Update.ESM, then the DLC ESM's).

An .ESP file is a plugin file that you will find for most mods. As a plugin file, it is treated and handled seamlessly by the game engine as a "true" plugin to the already-loaded .ESMs. This is what you'll most likely find as your mods, as they provide the most seamless integration to already-loaded or already-loadable data for the game engine to handle. .ESP files usually have a "master" file they request from the game engine to be loaded previously, and usually this is a .ESM file (like Skyrim.ESM and Update.ESM), but it could also be a .ESP file (for sub-mod interaction like the previous Mod A Mod B example in Part II).

Loose files are the files you will find in all the subdirectorys under your Skyrim's /Data/ directory. They are usually loaded after .BSA and take precedence in the hierarchy, usually for good reason. This is where you will find some texture replacer mods as, as the game engine is naturally set to give precedence to loose files not in a .BSA, and are structured in sub-directories that must match the ones inside the .BSA files they are supposed to replace. Skyrim in vanilla form (aka no mods and only official data) does have some loose files by nature, usually the intro movie, script files that cannot be in a .BSA due to the Papyrus script engine that is part, and used by, Skyrim, and the odd audio file. Mods that are script-heavy will have multiple loose files that are the scripts themselves.

Thats basically all the information of all those files in your /Data/ directory, so you know what each is and why messing around with an .ESM or .BSA may be a bad idea without a backup, or loose files for that matter.

Now, onto another community-authored tool that has become invaluable for mod usage stabilty and thus, savegame integrity when using mods:

TES5Edit. A variant of the -Edit series of tools meant to assist both modmakers and mod users in general mod data record cleaning and integrity checking. Why is this important. Any form of "dirty" edit is a potential clashing point for the game engine, which can lead to game instability, which leads to savegame integrity failure, and thus, corrupted saves. I am, of course, not counting the potential CTD's, incorrect mod behavior, incorrect base game behavior, etc that can come out of "dirty edited" mods[www.creationkit.com], as stated by the Creation Kit wiki page/guide on TES5Edit.

Gopher, of GophersVids, famed Fallout 3, Fallout New Vegas, and Skyrim modmaker, with a guide for mod-users on how to use TES5Edit.
* a guide on how to use TES5Edit to clean "dirty edits" in Bethesda's own .ESM files *

Yes, you heard Gopher right, Bethesda's own .ESM files contain dirty edits. Why did they release the files as they are? Well, the dirty edits are there because there is no need to clean them in a vanilla game. It is only when modding Skyrim and having dirty edit data entries clashing with mod data entries that issues arise.

A more in-depth guide for TES5Edit aimed for more mod-makers. In-depth guide.

So now you've learned something new about maintaining your own mods, and your Skyrim install, whats next? Well, hold yer' horses there...
IV. MAHMH, Mods And Healthy Modding Habits
So now you're ready to mod your Skyrim game with all the awesomeness, right? Well slow down there, young'in. Dont jump the fence without checking if its a short fall or a leap off a cliff.

Skyrim is unique amongst previous Bethesda's offering in one vital part for mod users, and that is certain bits of mod data will be saved in your save-game. You cannot stop this, nor fix it. This becomes a big issue for those who have a habit of "updating" mods as well. If your mod load list does not match what is contained in your savegame, untold number of problems can arise, which is why having a solid mod list that you do not deviate from until you finish a playthrough is strongly advised.

Gopher himself states why updating mods willy-nilly is a bad idea.

A couple of other tips:
1. Its best to read readmes, understand what a mod does, and if possible, test-game mods you wish to use. This is to prevent potential issues in an actual game where a mod issue arises in a game wherein a fix is impossible due to factors in an aged save. Get into the habit of running test-games with mods you wish to try out. Usage of the console commands[www.uesp.net] will be helpful in this regard, and you can tell if the mod is for you or not and can remove it from your mod list without causing potential damage to your actual planned real game and its saves.

Let me tell you, many tears were shed when my 150+ hour save was destroyed when I inadvertedly updated a small mod that had far-reaching implications with the save data, and corrupted the file itself, preventing recovery. All this could have been prevented if I read the updated readme stating I should not directly update and must follow the procedure to "clean" my save before updating. Never again. RTFM, there's a reason why people say this.

2. Once you have a chosen list of mods you want to run with for a playthrough, please do not deviate from this list. This is to prevent the aformentioned issue above as stated by Gopher. You will find that this is a godsend when you dont have to worry about mod updates when you stick to a game all the way to the end before changing things. This is also the reason why test-games are important, so as to find potential issues between mods if there are any.

3. If you must actually change your mod load order (if there is an extremely vital update and the documentation allows for game-in-progress updating is possible), read the mod readme/documentation/description page for exact updating instructions and follow them to the letter. Make a backup of your savegames and the mod version you use as well. If there is little to no documentation regarding the removal/unninstall procedure for the mod, follow "clean saving" steps as listed in this link[wiki.step-project.com]. Do note that still could cause unintended consequences and may not go as smoothly as possible, thus keep this in mind.

4. If you have two mods that change, affect, or adjust the same or similar thing, keep this in mind that there may be a direct incompatibility between the mods themselves. Again, check the documentation and make a judgement call on which mod to use. Using two seperate weather mods is inherently bad. Stick to a single mod that affects a certain thing in Skyrim, and dont complicate matters for yourself, your savegame, or your game in question.

5. If there is a mod you'd like to use that looks like it will make the game prettier or adds a lot of things to process, keep in mind the potential extra workload the Skyrim game engine and your PC must undertake to run the mod. ENB configs[www.enbdev.com] are pretty and all, but is notoriously heavy on one's CPU and GPU, and thus is only meant for high-end PC's which can play the base Skyrim game at max FPS to begin with. Mods that add a lot of things to the gameworld like Populated Lands Roads Paths[www.nexusmods.com] or any of the "Populated" family of mods are also known to stress and even crash the Skyrim game engine if you go all-out. Keep the general computing horsepower performance of your PC in mind when modding your Skyrim game.

6. If you are hell-bent on "unninstalling" a mod, its best to use any deactivation method built into the mod and leaving its files in your Skyrim Data folder, still ticked, and still being loaded. This is to prevent even more save-game corruption problems that are brought about by removing ESP/ESM files that are loaded into the save, and then suddenly no longer loaded and are treated as trash data (which can lead to save-game corruption). I know this is a bit of a pain, but this is the currently known safest option to "unninstall" ESP/ESM-based mods. This is also the main reason why I stress no.1, which is to test mods before using them in a proper savegame.
Epilogue, Final Thoughts, and Additional Resources
I hope my guide has been educational for you and that you walk away with a better understanding of the intricacies behind the curtain, so to speak, that brings forth your Skyrim experience, modded or not.

Additional questions and inquiries can be made in the comments section below, and I will do my best to answer them, or add their answers to the guide in a future FAQ section I wish to add :)

An excellent recommended mod list and guide is made by insane0hflex himself right hereinsane0hflex
He is a respected Youtube video maker and Skyrim mod previewer. He pretty much covers a majority of all the good stuff out there in his guide, but for those wishing to stay on this guide...

The Skyrim Total Enhancement Program (S.T.E.P.)[skyrim.nexusmods.com] is an all-in-one guide to generally enhance Skyrim in some fashion via the mods, keeping the intent and feel of Skyrim whilst adding to it and expanding upon it.

Skyrim Gems[www.skyrimgems.com] is a website that lists the little "gems" of mods out there that may have been ignored by the greater modding community due to how quickly the modding community grows. Trying to look for a specific type of mod? Skyrim Gems may have it listed in an easy-to-read list for you.

And of course, cant forget the Skyrim Workshop itself, and Skyrim Nexus[skyrim.nexusmods.com].

I hope my guide has been helpful to you at this point, and I wish you good tidings in your adventures in Skyrim, modded or not :) Do not forget to rate the guide if it has been helpful for you, and others too!
Additional Information Regarding 1.9 Legendary patch (updated 6-22-13)
As the 1.9 Legendary patch has been released, some information has come to light regarding the new mechanics that are introduced in the new patch that may collide with certain popular mods and the like that people are using nowadays, that may prove to become a major problem.

  • The Legendary patch adds a "legendary skill" system where you can turn a maxed-out skill into a "Legendary" skill. Whilst this is mod-independent to an extent, it is obvious that certain mods that change skill or perk mechanics will need to be checked if they've been updated for the 1.9 game version to be safe.
  • Since Bethesda has stated that 1.9 may be the last major change to the game, it is safe to assume that you need not worry too much about game version-to-mod incompatibilities in the future. This however does not mean that you can relax. Proper mod handling is still the best for a stable, safe, and fun modded Skyrim experience.
  • Some changes to mod structuring has been done by several modders, allowing in-progress unninstallation. Do note that its still best to double-check mods you have installed and see whether or not its safe to update, or remove from one's game. Some mod updates may require a "clean save" of which is iffy at best, considering the savefile structure.
  • Unofficial patches are regularly updated every couple of months. Still, its best to double check whether or not if there's a change and have that patch update when the changes are far from your character. For example: Unofficial Dragonborn Patch? Dont be on Solstheim.
Additional Information Regarding Skyrim Memory Usage And Crashing(updated 2-9-14)
A discovery involving Skyrim and heavy RAM usage leading to a reproducible crash is tied to heavy mod usage with large texture sizes or assets (like texture replacers).

Best described by Gopher himself.


Gopher himself covers what is known, and offers a (very advanced) tool to help monitor Skyrim's resource usage from your PC. All info is from the STEP team, so kudos to them. I'm just spreading the news.

Why 3.1GB? No one really knows. Not much you can do here except one: be sensible in your mod usage, avoid large texture packs, and the like.

One way to alleviate even more of this is by using ENBoost, a memory allocation setup that works in combination with ENB to reallocate memory usage. Do note this will NOT allow you to go heavy on memory-heavy mods like texture replacers and the like if you couldnt before. It just allows ENB(and ENBoost, obviously) to utilize your videocard's VRAM more, and as such works best for owners who have large VRAM sets on their video cards.

The best way I could help folks who want to use something as advanced as ENBoost and ENB's in general is to point them to STEP's own ENB page[wiki.step-project.com] on the subject. Be advised ENB's in general are a highly advanced topic on their own and require a lot out of the user (in terms of technical ability) and their system (in terms of processing horsepower).

Another more recent development in alleviating Skyrim's lackluster memory handling is in expanding its "heap" size. Before I lose you, let me explain:

Basically, in the simplest terms possible, Skyrim, at start, allocates two blocks of memory for its own usage, around 256mb each, seperate from bulk data usage like texture data, model data, etc. One is the DefaultHeap and the other is the ScrapHeap. DefaultHeap is the important one here. In the base vanilla Skyrim game, such a memory allocation setup and size are just fine for normal Skyrim playthroughs, and Skyrim is supposed to create a second 256mb block for DefaultHeap usage. The problem arises when you have mods that require more memory allocation from the Skyrim game engine, alongside Skyrim's inability to create this second memory block when its supposed to.

The problems from Skyrim basically filling up that 256mb block it uses ranges from the dreaded Infinite Loading Screen problem, direct Crash to Desktop (CTD), and freezes. The solution by an intrepid modder by the name of Sheson is to forego the need for Skyrim to create that second memory block, and make the first one big enough.

Details of said fix is here[enbdev.com], along with technical information for more able users to peruse.

Gopher himself has recently put up a video of his experience testing such a "fix":


Basically, in short, it expands the DefaultHeap block size that Skyrim allocates from 256mb to 512mb, which for most cases is more than enough to ensure stable memory handling from the Skyrim game engine.

Still, the best advice stays the same in all cases: be sensible in your mod usage. There's only so far you can go in modding Skyrim before things go wrong, and even my guide's advice can only go so far for you.
10 Comments
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richard.l.homan Dec 24, 2013 @ 12:03pm 
Slightly disappointed Mod Organizer wasn't mentioned. It's kind of the completion of the trifecta of mod managers. Very good guide for beginners, though. :)
LP Dec 11, 2013 @ 3:05pm 
Nice guide.
Spencer Aug 26, 2013 @ 1:40pm 
well I wish the entire thing would work for me..oh well.. sadly no more skyrim.. sadface
chebonaparte Jul 17, 2013 @ 7:13pm 
well done great thread. now if i can nly get 5mins peace quiet and coffee to concentrate on it properly! ;) kudos
YoYoduh Jun 23, 2013 @ 5:51pm 
WOW have I got alot to learn ! Thank you for giving me a place to start and at my age to finish!
Jogon Jun 21, 2013 @ 5:05pm 
A very informative article with directions from other contributors. I congratulate you on explaining how the Skyrim game works and how the files should be loaded for an error free play through.
maxx_fennig Jun 18, 2013 @ 1:50am 
this is a fully awesome tutorial ! well presented , easy to understand and full of vital information for new mod users and aspiring modders . sincerest thanks for your time and effort and your dedication to the modding community .
Manitou May 2, 2013 @ 10:03pm 
Really well done thanks for your presentation of this, very appreciated!
wolftalker7799 Feb 14, 2013 @ 1:15am 
i use MODS and have few issues now from trial and error.Your wonderful guide would have been a blessing,THANK YOU for you time! It showed points i will use! and provided me with better info than i ever had! good job!
HSIAMetalKing Jan 23, 2013 @ 1:01pm 
Thanks for taking the tiem to write this, it cleared up a lot of confusion I was having about modding jargon :p