A flat, house or other lodging for secondary or occasional use, literally 'foot on ground' in French (4-1-5)
I believe the answer is:
pied-a-terre
(Other definitions for pied-a-terre that I've seen before include "Small home kept for occasional use" , "Small secondary flat or house" , "Lodging kept for occasional use (French)" , "Dwelling for occasional use" , "bijou accommodation" .)