Create continuous tasks/habits

Is it possible to create two tasks, with a specific buffer time between them? For example:

Start X - process takes 3h, but doesn't require my invovlement so it shouldn't take up time in my calendar - Finish with Y.

Simplest example would be: gather & put in laundry is Task 1, and after 2h, take it out and hang it - Task 2.
I want to make sure they are always scheduled the same day, obviously, but I also don't want to reserve 2h for them, because the actual 2h are free.

Thanks!