How is my house's foundation constructed?
Wild guess (without photos):


6" concrete block structure (common for residential foundations--4" is mostly used for a shorty garage wall base and cases where actual brick ledges are present)
~1" thin brick veneer outside


You may also have a 6" foundation that transitions to a 4" block behind a full brick veneer. 

You should be able to determine brick thickness at corners or penetrations. That'll tell us a lot.