when opening is wider than the new door...

Hanging a pre-hung door is not always as easy as pie.  Plaster walls in older buildings are roughly 5 and 1/2 inches thick.  When you want to install a new door, you may have a problem because most pre-hung doors are only 4 and 9/16 inches wide. The solution is custom-made jam extensions.  I was faced with this exact problem this week.  The picture on the left shows the gap that needed be covered and the picture on the right shows the new jam extension I made and installed.