What is the cost of a residential sprinkler system; more specifically, what is the square footage cost?

In November of 2008, I attended a meeting of Pennsylvania’s State-Wide (Fire) Advisory Board, ostensibly to discuss residential sprinklers.  At that meeting, I got hijacked to co-chair the Pennsylvania Fire Sprinkler Coalition … and so the adventure began.  From the beginning, we adopted the following philosophy:

• Answer every false statement with a documented truth
• Do not make statements that can’t be proven

One of the subjects that always seemed to cause consternation was the cost/ft2 of residential fire sprinklers … opponents quoted costs that were generally double the national average.  At this point in time, my own community had been requiring residential sprinklers for two decades and the costs closely mirrored the national average, so we attempted to find the discrepancy.  To that end, the Pennsylvania Fire and Emergency Services Institute, under the leadership of Chief Don Konkle, hosted a meeting with our opponents at Pennsylvania Fire and Emergency Services Institute’s headquarters in Harrisburg, PA.  We wanted to open a dialogue; that which we found was interesting.

• Imagine a 1 ½ story home with a basement.
• The footprint of this home equals 1,000 ft2.
• The sprinklers for this home cost $3,200.
• What is the cost per square foot?
  • Our calculations showed:
    • 1,000 ft2 first floor which require sprinklers, plus
    • 1,000 ft2  basement which requires sprinklers
    • Equals 2,000ft2
    • $3,200 / 2,000ft2 = $1.60 / ft2
  • Our opponents stated that the basement square footage didn’t count for purposes of marketing the home; that this was a 1,000ft2 house; as such:
    • $3,200 / 1,000ft2 = $3.20 / ft2

According to realtor.com,

As a general rule of thumb, a finished basement typically doesn’t count toward the overall square footage, especially if the basement is completely below grade –  a term that means under ground level.  What is included ultimately depends on which state you live-in.¹

Study after study has shown the cost of the installation of residential sprinklers at half the cost touted by the builders.  While sprinkler advocates compare cost/actual square footage in which sprinklers are located, opponents compare cost/marketable square footage.  Prospective home owners need to ask not the cost per square foot, but the actual cost and the actual square footage of the home, including the basement.

¹ Retrieved from https://www.realtor.com/advice/buy/should-a-nicely-finished-basement-count-in-the-pricesquare-footage-of-a-home/