Need help on shapes

Well, I don’t know how to solve this, the house is made of logs, and I can’t do subsurf in it’s current condition (they turn in to round surfboards or something like that). Help is very appreciated!

(Be patient with me, I’m learning as fast as I can)

Put an edge loop on the ends of the logs, the nearer the end it is the sharper the edge will be

Thanks a lot!