Do you mean perimeter?
The square footage (area of the house's footprint) is length times breadth = LB=15000ft2.
The perimeter is 2(L+B). So B=15000/L feet and the perimeter is 2(L+15000/L) ft.
Therefore we need to know the length or breadth of the house to find its perimeter, and knowing the area is not enough.
If the house has a square footage then L=B=122.5 ft approx. and the perimeter would be about 490 feet (large house or mansion).
A house measuring 120ft×125ft has a perimeter of 490 ft. This is rather large for a domestic dwelling which has a footage of about 750ft2, so maybe the figure you quoted is not the square footage?