Is there a way to make folders open in a new window by default in OS X El Capitan?
Set folders to open in tabs or windows
  
  
  In the Finder, choose Finder > Preferences, then click General.
  Select or deselect “Open folders in tabs instead of new windows.”
  
  
  Open folders in tabs or windows
  
  Press the Command (⌘) key while you double-click the folder.
  
  The folder opens in a new tab or window, depending on your Finder
  preferences. Tip:   If the Finder toolbar and sidebar are hidden,
  double-clicking a folder without pressing the Command key opens the
  folder in a new window.
  
  To open a new Finder window without opening a specific folder, choose
  File > New Finder Window or press Command (⌘)–N.


Info from: OS X Yosemite: Open folders in new Finder tabs or windows