Trying to get outside area to work correctly

When i try to make a grass area, i can not seem to ever get the grass area (outside area) to but up against the house.

So is there a way to resize it to do this. I do not see the option to do this, or am i just doing something completing wrong.

Every once in a while, i get it to go agaist the house, but most all the time, i try to make a line across the edge of the house and it just does not work. Thank you to whoever can find me a answer to this...