I'm sure the world's civil engineers will be pleased to learn that, since they already know the tensile strength of concrete and since they use surveyors to map a site, they're merely assembling bridges and freeways rather than engineering them.
You don't need to be a civil engineer to design a single family house. The properties of the common materials like 2x4s are so well known that you need very little training to draw up a print that can be built - you look up in a chart how long a 2x12 can span and so long as you stay under that size your are okay.
Now in a typical house the floor and roof use trusses that are engineered because in those areas engineering matters. Even then they are mostly taking a bunch of trusses already designed and putting their stamp on the system working.
As buildings get larger/more complex though it becomes harder and harder to build the needed charts. Eventually you need a civil engineer to do a lot of calculation (with the help of a computer) because the building is different enough from anything before.
