you just need a example sentence: my family live in a big house (我家住在一所大房子里)
家=family home(sometimes explainable as house), 房子=house
but in some cases, 家=房子，for example:
你家有多大? = 你的房子有多大？
我家有露台和后院 = 我房子有露台和后院
- so, if you want to express family or home, you can use 家, if just the accommodation, use 房子 is correct.
- 家 can explainable as home, family or house, but 房子 cannot explainable as family.