How to Import Windows Updates in the Windows reference Image from the MDT

The first step is to deploy Windows Image from your MDT as a Virtual Machine. You can follow the guides base on your infrastructure.

When the new Virtual Machine from your Reference Image is ready and has Internet access you must install the Powershell module PSWindowsUpdate.
Open a Powershell and type the following command
Install-Module PSWindowsUpdate
You will get a warning but just click Yes.
Now type Get-WindowsUpdate
Wait until receive the Windows Updates that must be install and you will get a list.

Open the Microsoft Update Catalog and download the Windows Updates which are missing base on the KB and the Windows OS that you have.

After you have download all the Windows Updates we are ready to add in your Image.

Login in your Server with the MDT
Create a folder with a name that you are prefer to copy the files that will be use.
Go in Operating System folder from MDT (Deployment Shares) with your image that you want to import the Windows Updates.
In my scenario is the Windows Server 2016 Std
Open the folder sources and copy the files boot.wim and install.wim in the folder that created above. For me is the win2016 folder.

Create a subfolder into the win2016 folder as updates or whatever you want and copy the Windows Updates that you have downloaded.
Open a powershell command as administrator
Type Get-WindowsImage C:\win2016\install.wim
You can see the 4 different options that included in this Windows Image.

After remove the first option type again Get-WindowsImage C:\win2016\install.wim and remove the unecessary options base on the ImageIndex
Now i have only the Windows Server Standard option.

You can keep any Version of the Windows Server base on your requirements.
Just be careful the ImageIndex number to be the right one when remove the options.
Now let's create a new folder.
Type mkdir c:\offline

We will use the offline folder to mount the Windows image and after add the Windows Updates
So type Mount-WindowsImage -ImagePath c:\win2016\install.wim -Index 1 -Path c:\offline
Wait until finish

Go in offline folder and you will see all the Windows folders after setup the Windows Server 2016

Now it's time to add the Windows updates
Type
Add-WindowsPackage -Path C:\offline -PackagePath C:\win2016\updates\
Wait until finish the import.
The time depends of the windows updates size and the Server\Workstation performance

When the import of the Windows updates finished successful we must Dismount the Image
Type the following command
Dismount-WindowsImage -Path c:\offline -Save
The time to dismount the image depends from the Windows Updates which import and the Performance

Until now we have done the following:

Setup if you don't have already the Reference Image to identify which updates must download.
We have downloaded the required Windows Updates from the Microsoft Update Catalog,
We use DISM commands to import Windows Updates in the Windows Image that already have imported in MDT.

Now we need to proceed with the following tasks:

So let's proceed with the above tasks

Right click in the Operating System that you want to replace with the new up to date and select Properties
Check the Path.

Copy and paste the folder in your Download folder
Copy the install.wim and boot.wim that we use to import the Windows updates in the source folder of the Windows Image that copy in your Download folder

Import the Windows Image in your Download folder with the new files install.wim and boot.wim in MDT.
I wrote an article Building a Custom Windows ISO with MDT 2013 that you can find how can import the Operating System
After import the Windows Image go In the Task Sequence that you have already created for the previous Operating System.
Click in Task Sequence Tab
Expand the Install folder
Select the Install Operating System. In the right side click Browse

Now you are ready to Deploy the updated Windows Image.