Windows Installer Files bloating up my SSD space; how do you get rid of it?

[dogfishunlimited]

Spent some time today trying to delete files on my SSD storage (101 gb out of 117 gb) by deleting apps, and while it did a sizable number in freeing up space, I noticed that most of the remaining storage occupied was oddly enough, within the System and Reserved parts.

I did some digging on some articles, stumbling into this post which got me started on figuring out this problem, to which I downloaded TreeSize to figure out what was taking up so much space. In the end, I didn't have the same problem as that user, but I did find out that what was taking up most space was the Windows Installer files.

to which I found that most of the problem was with these .msp and .msi files taking up a exorbitant amount of space in here.

Does anyone know if there's a way to get rid of them? I've read enough that it's generally dangerous to try and manually delete them because you risk breaking something, so I will not dare touch the delete button here. I'm not very tech-savvy, I have the technical knowledge and slowness around computers like someone's 90 year old grandmother, so I would appreciate if some terms get dumbed down and explained simply, but thoroughly.

 

[ChatGPT]

Hi dogfishunlimited — good catch, and you are right to be cautious.

Short answer​

Do not manually delete anything from C:\Windows\Installer.
That folder is not normal “junk.” It is Windows’ storage cupboard for installer/repair/update files used by installed programs.
In plain terms:

• .msi = installer package
• .msp = patch/update package
• C:\Windows\Installer = Windows’ hidden cache for those files

If you delete the wrong ones, programs may later fail to:

• uninstall
• update
• repair themselves
• install future patches

Your screenshot shows about 20 GB in C:\Windows\Installer, which is large, but not impossible on a small 117 GB SSD, especially if Office, Adobe, Visual Studio, games launchers, printer suites, etc. have been installed over time.

---

What I would do first​

1. Leave C:\Windows\Installer alone for now​

Do not:

• manually delete .msi or .msp files
• take ownership of the folder
• use a registry cleaner
• use old tools like “Windows Installer Cleanup Utility” or random “MSI zap” guides

Those can cause more problems than they solve.

---

Safe cleanup steps​

2. Run Windows’ built-in cleanup​

1. Open Settings.
2. Go to System > Storage.
3. Click Temporary files.
4. Let it scan.
5. Select safe items like:
   • Windows Update Cleanup
   • Temporary files
   • Delivery Optimization Files
   • Recycle Bin, if you do not need those files
6. Be careful with Downloads. Only tick it if you really want to delete your Downloads folder.
7. Click Remove files.

This probably will not shrink C:\Windows\Installer much, but it may free other space safely.

---

3. Clean Windows component leftovers​

This cleans Windows update/component leftovers, not the Installer folder, but it is safe and often helps.

1. Right-click Start.
2. Open Terminal/Admin or Command Prompt/Admin.
3. Run:

DISM /Online /Cleanup-Image /StartComponentCleanup

1. Wait for it to finish.
2. Restart the PC.

Do not use /ResetBase unless you understand the trade-off, because that makes some Windows updates impossible to uninstall later.

---

4. Check hibernation space​

If you never use Hibernate, you can disable it and often recover several GB.

1. Right-click Start.
2. Open Terminal/Admin.
3. Run:

powercfg /h off
To undo it later:
powercfg /h on
Note: this also disables Fast Startup.

---

5. Reduce System Restore storage​

Your “System & reserved” category can also include restore points.

1. Press Start.
2. Search for Create a restore point.
3. Open it.
4. Select your C: drive.
5. Click Configure.
6. Lower Max Usage to something reasonable, for example 3–5 GB.
7. If you need space urgently, click Delete to remove old restore points.
8. Create a new restore point afterward.

Warning: deleting restore points means you cannot roll back to those older restore dates.

---

If you specifically want to shrink C:\Windows\Installer​

The safest practical method is not to delete files yourself, but to use a tool that checks whether installer files are still referenced.
The commonly used tool for this is PatchCleaner.
If you try it:

1. Create a restore point first.
2. Back up anything important.
3. Run PatchCleaner.
4. If it finds “orphaned” installer files, choose Move, not Delete.
5. Move them to an external drive or another folder, for example:

D:\Moved_Installer_Files

1. Use the computer normally for a few weeks.
2. Test Windows Update and your main apps.
3. If nothing breaks, then you can consider deleting the moved files later.

Important: I would not make PatchCleaner your first step. Use it only if you still need space after the safer cleanup methods above.

---

Best long-term fix​

Because your SSD is only about 117 GB, Windows is going to feel cramped no matter what. A 20 GB installer cache hurts much more on a 128 GB drive than it would on a 500 GB drive.
If this is a laptop/desktop that allows it, the best long-term solution is:

• upgrade to a 500 GB or 1 TB SSD, or
• move large apps/games/user files to another drive

---

My recommendation for your case​

Since you now appear to have around 37 GB free, I would not touch C:\Windows\Installer yet.
Do this order:

1. Run Temporary files cleanup.
2. Run the DISM cleanup command.
3. Disable hibernation if you do not use it.
4. Reduce old restore point storage.
5. Only then consider PatchCleaner, using Move, not Delete.

You were absolutely right not to press Delete in TreeSize. That folder is one of the places where “it looks like junk” but can break installed programs if cleaned manually.