An overcrowded attic and a messy common room are two examples you will be able to solve with the following technique.
After years of living in shared flats, I made this observation.
People love to add things to a household rather removing them. There's even scientific indication humans use addition over subtraction in problem-solving.
Fact is that with more stuff, our homes will easier become messy. Having less is not only minimalistic, it prevents chaos.
There is an issue with removing something from your shared flat. You need to ask every member if it belongs to them and what they wish to do with it. And this needs to be done for every item. That’s a lot of time discussing. Inefficient!
Let’s turn this around and use these easy to implement stages to remove stuff over time.
Stage 1: Collection
First we want to collect all the stuff not used and put it all in one place with public access. For example, taking a bucket in the entrance room.
Create a communication channel everyone has access to. Use a chat group or a message board in the kitchen.
Communicate that unused stuff was collected in a bucket in the entrance room. The items will stay in that place for one week. If not picked up by anyone, it will be transferred to Stage 2.
Stage 2: Transit Zone
Everything not picked up in Stage 1 will be transferred to the Transit Zone. A place which is not directly accessible to everyone anymore, like an attic. There it will be kept for 90 days. If an item is important enough to be raised in that timeframe, they can just take it back to their room.
Stage 3: Purge
And yes, you guessed it right: Purge is incoming! If nobody is missing items from it, it can be sold for the good of the flat.
This purge can be repeated in a comfortable interval. In my experience, 3 to 4 months was a good interval.
After implementing, removing becomes the new default. Now you need to act if you want to prevent an item being sold.