Anybody know of a good cad app for building a house.

Look at Sketchup...should do everything you should need it to do. There is a minimal learning curve, however there are many resources that will help you master it.

I did all of the construction drawings for our house in SketchUp. It is a pretty powerful program and there are tons of videos on youtube to help you learn how to run it.

Here is a pic of the model that I did before we built our house. I modelled every structural member.



While messing with designs, I used SketchUp's shadow feature to figure out how long to make the overhangs. I wanted more sun hitting the windows in December.



I also used it to detail some of the construction details that I wanted the builder to follow.

Another vote for Sketchup, though there's definitely a learning curve.

Not as complex as the other examples above, but my greenhouse:

Did you guys buy the version of sketch up or was it the free version?

I used the free version, "Make".

Sketch up

I used the free version to model a barn.  I put in major structural elements and features.  For things like windows I just grabbed models off the internet and tossed them in.  Close enough.  Heck, even had a horse in there.

It was easy to get a good idea of what the building would look like.  To have actual construction drawings will take more work, but as mentioned there are hours and hours of video on YouTube

Slanted makes a good point. SketchUp has an awesome 3d warehouse with models of almost anything that you would need. I like to grab models of furniture to size out rooms.

The Make version will do everything that you need to do unless you are going to try to have an inspector sign off on drawings. Then you will want the Pro version which will give you the Layout program that is used to make drawings.