I recently laid a new wooden floor in my lounge and was amazed to find out just how far away from right angles some of my corners are. For example, measuring from a wall to one side of the door on the opposite wall, 386 cm. From the wall to the other side of the door, 383 cm. So, in the space of a door's width (70 cm) that part of the wall is 3 cm away from being parallel with the opposite wall. For a house that is just 10 years old, that strikes me as really poor!