Q:

Out at the house (Hemingway's To have and Not Have)

This is from Hemingway's To Have and Not Have.  It's not clear to me where they were having lunch.  
Out at the house Marie and the girls were having lunch.  
"Hello Daddy," said the oldest girl. " Here's Daddy."  
... (conversation omitted)
when the girls were out of the room he said to Marie, "Cut it up, will you?" 
This looks strange to me.  At the first sentence, they were all having lunch "out at the house."  And after conversation "the girls were out of the room."  I wonder where Marie and her girls were having lunch first.  May at terrace?  Or the yard? 

A:

"Out" in this case isn't referring to location as it relates to the house, but rather is saying that the house is some distance away from the speaker.   For example, "out in the country" doesn't necessarily mean something is outside, just that it's in a rural area.   
Marie and the girls were simply having their lunch "at the house", i.e. on the property.   This doesn't give you enough information to know exactly where they were; a terrace or porch is a possibility, but they could also be inside.   It's only when you get additional information (when the text mentions that "the girls were out of the room") that you can infer they were originally inside.