How to Clean Install Windows 11 With WIMUtil & UnattendedWinstall

To do a clean Windows 11 install with WIMUtil and UnattendedWinstall, download the Windows 11 ISO, load it into WIMUtil, use the Download UW button to embed the latest UnattendedWinstall answer file, export your current drivers, save the customised ISO, and write it to a USB with Ventoy. Boot from the USB, delete the old Windows partitions, and let Setup install a debloated, pre-configured copy of Windows 11 that applies your drivers automatically.

Applies to: Windows 11 (23H2, 24H2, 25H2) | Last updated: April 15, 2026

Key Takeaways

• WIMUtil is my PowerShell-based utility that customises a Windows ISO by injecting an answer file, exporting your installed drivers into sources\$OEM$\$1\Drivers, and saving a new ISO — all without touching the original.
• UnattendedWinstall’s autounattend.xml skips OOBE entirely, creates a local account, disables bloat, and applies optimisations. The Download UW button in WIMUtil grabs the latest answer file for you.
• Exported drivers go into the sources\$OEM$\$1\Drivers folder of the ISO. Windows Setup auto-detects and installs them during deployment — you don’t need to touch drivers after install.
• Ventoy is the cleanest way to boot the customised ISO — copy the ISO file onto a Ventoy USB and pick it from the boot menu.
• Backing up and reinstalling system-wide takes about an hour with this workflow. The resulting install is fully debloated, signed in as a local account, with drivers installed.

Quick Steps

1. Back up Desktop, Documents, and Downloads to a second drive.
2. Save a software bundle from UniGetUI for easy reinstallation later.
3. Download the latest Windows 11 ISO using my Windows 11 ISO guide.
4. Run WIMUtil in an elevated PowerShell: irm "https://github.com/memstechtips/WIMUtil/raw/main/src/WIMUtil.ps1" | iex.
5. In WIMUtil: load the ISO, click Download UW, export drivers, save as a new ISO.
6. Install Ventoy to a USB drive and copy the customised ISO onto the USB.
7. Boot from the USB, select the ISO, delete old partitions on the target drive, and let UnattendedWinstall drive the install.
8. After first boot, restore your files and run your UniGetUI bundle to reinstall apps.

Why Use WIMUtil + UnattendedWinstall

A stock Windows 11 install gives you a default Start menu full of Microsoft ads, a mandatory Microsoft account, a dozen preinstalled apps you’ll never open, and privacy toggles nudged toward “share everything.” Cleaning all that up by hand takes an hour. With an UnattendedWinstall-customised ISO, Setup applies the answer file during deployment and you land on a clean desktop with a local account, most of the bloat removed, and your drivers already in place.

WIMUtil is the utility I wrote to make that process as simple as possible — no manual XML editing, no mounting WIM files with DISM, no command-line ceremony. It wraps the whole pipeline behind a GUI: load ISO, click a few buttons, save new ISO. If you want the full comparison against other custom ISO tools, see my guide on the best custom Windows ISO tools.

Step 1: Back Up Everything You Want to Keep

A clean install wipes the C: drive, so anything stored there is gone. The usual suspects:

• Desktop
• Documents
• Downloads
• Pictures, Videos, Music
• Anything you’ve saved under C:\Users\YourName\

Move these folders to a second internal drive, external drive, or cloud storage. If your setup already stores user data on a secondary drive (e.g., D:\), skip this step — just confirm nothing important lives under C:\.

Tip: After this reinstall, point your Desktop, Documents, and Downloads folders at the secondary drive permanently (right-click the folder → Properties → Location tab → Move). Future reinstalls become trivial — the user data never sits on the OS drive in the first place.

Step 2: Save a UniGetUI Software Bundle

UniGetUI can export every installed app as a single bundle file, then re-install them all on a fresh Windows with one import. This is the fastest way I know to recover a full software setup after a reinstall.

1. Open UniGetUI and switch to the Installed Packages tab.
2. Click Select all.
3. Click Export as bundle and save the JSON file to your USB drive or secondary storage.

The bundle is a plain JSON file — you can open it in Notepad to see what’s in it. After reinstalling Windows, you install UniGetUI again, click Import bundle, point at the JSON, and it queues every app for reinstall.

Step 3: Build the Custom ISO with WIMUtil

Start by downloading the Windows 11 ISO — my Windows 11 ISO download guide has the fastest method. You want the multi-edition ISO from Microsoft directly, not a third-party mirror.

Launch WIMUtil

WIMUtil runs straight from PowerShell with one command. Open PowerShell as Administrator (right-click Start → Terminal (Admin)) and paste:

irm "https://github.com/memstechtips/WIMUtil/raw/main/src/WIMUtil.ps1" | iex

The command fetches the latest WIMUtil script from my GitHub repository and runs it in memory. No install, no leftover files. A GUI window opens after a few seconds.

Load the ISO and Pick a Working Directory

1. Click Select Windows ISO and point at the ISO you just downloaded.
2. Click Select Working Directory and pick an empty folder with at least 10 GB of free space — WIMUtil needs room to extract and repackage.

Add the UnattendedWinstall Answer File

This is the step that turns a plain ISO into a debloated, hands-off install.

• Click Download UW to grab the latest UnattendedWinstall answer file directly from the UW repository. WIMUtil places the file in the root of the installation media automatically.
• If you prefer your own answer file (e.g., something you built with the autounattend.xml generator), click Add Answer File and point at your local autounattend.xml instead.

The answer file sits at the root of the ISO. When Windows Setup runs, it detects autounattend.xml, reads it, and applies every setting in one shot — edition selection, language, disk partitioning, account creation, app removal, privacy defaults.

Export Your Drivers

If you’re reinstalling on the same machine, the drivers already working in your current Windows install are the fastest way to get the new install fully functional. WIMUtil uses DISM to export them and drops the folder into the ISO where Setup will pick it up.

1. Click Export Drivers in WIMUtil.
2. WIMUtil runs dism /online /export-driver in the background, pulling every third-party driver into the ISO’s sources\$OEM$\$1\Drivers folder.
3. Windows Setup auto-detects the $OEM$ folder during install and installs those drivers silently.

Note: If you’re preparing an ISO for a different PC, skip the driver export step — you don’t want your current machine’s drivers polluting another system. Instead, grab drivers from the target PC’s manufacturer, or use Snappy Driver Installer Origin on the fresh install.

Save the Customised ISO

Click Create ISO. WIMUtil rebuilds the ISO with your answer file and driver folder included. The save dialog lets you pick a filename and location — I usually name it Windows11_Custom_24H2.iso so I know at a glance what’s inside.

Step 4: Make a Bootable USB with Ventoy

Ventoy turns a USB drive into a multi-ISO boot device — you copy ISO files onto it like regular files, and a boot menu lets you pick which one to install. It’s much faster than rewriting a USB with Rufus every time you want a different ISO.

1. Download Ventoy from the official GitHub page.
2. Run Ventoy2Disk.exe, select your USB drive, and click Install. This wipes the USB and installs the Ventoy bootloader.
3. Copy your WIMUtil-customised ISO onto the USB — just drag and drop.

For the full Ventoy walkthrough, see my Ventoy rescue USB guide. If you’d rather use a single-ISO Rufus USB, my Rufus bootable USB guide covers that workflow.

Step 5: Boot and Install

Before rebooting, rename your current C: drive to something obvious like Delete Me. Drive letters change in Windows Setup — the label won’t.

Boot From the USB

1. Restart the PC with the USB plugged in.
2. Press the boot menu key as the BIOS screen appears. Common keys: F12 (Dell, Lenovo), F11 (MSI, ASRock), F10 (HP), Esc (some Acer). Check your motherboard manual if in doubt.
3. Pick the UEFI option for your USB drive if the menu shows both UEFI and legacy entries. UEFI gives you a GPT install, which is required for Windows 11.

Ventoy’s menu appears — pick the custom ISO, and Windows Setup starts. Because UnattendedWinstall is in play, Setup runs through most of the steps automatically.

Partition the Drive

1. When Setup reaches the partition screen, look for the drive labelled Delete Me (the label survives the boot).
2. Note the Disk number for that drive — you’ll only touch partitions on this disk.
3. Select each partition on Disk X one at a time and click Delete. Continue until the disk shows one block of Unallocated space.
4. Click the unallocated space and click Next. Setup creates the correct partition layout automatically.

Warning: Only delete partitions on the drive you intend to wipe. If you have a secondary drive with data on it (photos, documents, games), double-check its Disk number and do not touch its partitions.

Setup copies files, expands them, and reboots. Total time is usually 15–25 minutes on an SSD. Because of UnattendedWinstall, OOBE is automated — you land on the desktop without clicking through the usual Microsoft account nonsense.

Step 6: Post-Install Tasks

Restore Your Files and Redirect User Folders

Copy your backed-up Desktop, Documents, and Downloads folders back to the secondary drive. Then right-click each user folder (e.g., C:\Users\YourName\Desktop) → Properties → Location tab → Move, and point them at the corresponding folder on your secondary drive. From now on, Desktop and Documents live off the OS drive.

Reinstall Apps from the UniGetUI Bundle

Install UniGetUI on the fresh Windows install. Open it, click Import bundle, point at the JSON file you saved in Step 2. UniGetUI queues every app that has a WinGet source and installs them in batch.

Verify Drivers

Open Device Manager and look for any entries with a yellow warning triangle. With the driver export step earlier, you should see almost none. For anything still missing, use Snappy Driver Installer Origin or grab the official driver from the PC manufacturer’s support page.

Customise the Look

UnattendedWinstall does a lot of cleanup, but the UI itself is still vanilla Windows 11. If you want the Windows 10 Start menu back, the classic right-click context menu, or finer-grained control, these are my go-to tools:

• StartAllBack — restores the Windows 10 / 7 Start menu and full taskbar.
• Shell by Nilesoft — customisable right-click context menu (no more “Show more options”).
• Custom mouse cursors — clean replacements for the default Windows pointer.
• Winhance — for any remaining debloat, privacy, or optimisation tweaks UnattendedWinstall didn’t cover.

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Frequently Asked Questions

Is WIMUtil free?

Yes. WIMUtil is an open-source PowerShell tool hosted on GitHub. There’s no installer and no licence fee — the irm | iex command downloads the latest version fresh each time you run it. You can inspect the source at github.com/memstechtips/WIMUtil.

Can I reinstall Windows without losing files?

Only by doing an in-place upgrade instead of a clean install — that preserves apps and files while refreshing Windows. My in-place upgrade guide covers that workflow. A clean install with this guide will wipe the drive, which is why the backup step is mandatory.

What’s the best tool for creating a bootable USB?

Ventoy if you want to keep multiple ISOs on one USB and pick which to boot. Rufus if you want a dedicated single-ISO installer. Both handle Windows 11 ISOs correctly — Ventoy is just more flexible for long-term use.

How do I check if drivers are missing after the install?

Open Device Manager (right-click Start → Device Manager) and scroll through. Anything with a yellow exclamation mark is missing a driver. If you exported drivers during the WIMUtil step, you should only see missing drivers for hardware that wasn’t attached during the export (e.g., a printer that was unplugged at the time).

Should I unplug other drives during installation?

Optional, but recommended on first attempts. Unplugging secondary drives physically removes the risk of deleting the wrong partition. If you’re confident with Disk numbers, labelling the target drive Delete Me is enough to identify it safely.

Can I use WIMUtil on a PC I’m preparing for someone else?

Yes. Skip the driver export step in that case — the other PC will have different hardware, so your exported drivers aren’t relevant. Just add the UnattendedWinstall answer file and save the ISO. After install on the target PC, use Snappy Driver Installer Origin to install the correct drivers for that hardware.

How do I streamline software reinstallation next time?

Create a UniGetUI bundle once, keep it updated every few months, and store it somewhere that survives reinstalls (cloud, USB, secondary drive). After every clean install, re-install UniGetUI and import the bundle — every app installs automatically.