A request I hear a lot when implementing Teams is the ability to make files read-only in certain channels. There is also an uservoice item to request such a feature.
Microsoft Teams, with the underlying Microsoft 365 Groups technology works best (in my opinion) if you keep it as simple as possible: You need a number of people to work together, so you want to give them the tools to do that. Teams is brilliant in that: you grab some people and throw them in a Team as members or owners and you are done. Everyone can just work together! When you have Teams for your departments, projects are other forms of collaboration, remember to set such a topic on the agenda of your governance team!
Organisations coming from a fileshare, or even a SharePoint platform have always known the ability to make certain folder or containers read-only for certain people. Examples would be procedures that only a few people can change but everyone needs to see, or just parts of a project where not everyone should be making changes to the files.
I know organisations that would give read-only access to the whole organisation for (almost) all files and folders, simply because that helps in transparancy.
Steps to make files in a channel read-only for members
Remark: You need to be an owner of the Team to set this up.
Step1: go to the channel. Open up the Files tab and click on the “open in SharePoint” button. This will open the browser and show you the files you have in the Teams channel.
Step 2: Go up one level by clicking on the documents button. You should now see all the names of the channels you have in Teams, but as folders.
Note: Private channels are not listed
Click on the … next to the folder with the name of the channel you want to change. Click Manage access.
Step 3: A pop up will appear on the right side of the screen. This allows you to manage the security of the folder. Change the security on the folder and the Files in Teams will be changed too.
Go to the members in the list and change the ability from “can edit” to “can view”.
The result is that when a members goes to the Files tab, they will notice that every file now has a new icon next to it, marking it as viewable only. When they open up the file it will be in view mode, without a way to edit the document.
This way you can set all the channels that are necessary to read-only for the members.
When your file security needs are different, know that you can manage them in SharePoint too: Allowing certain people to make changes, or only blocking a number of documents to be changed are also possible.