A Minnesota code requirement that all new single-family homes larger than 4,500 square feet be constructed with automatic fire sprinkler systems was declared invalid on Wednesday by the state Court of Appeals.

The Builders Association of the Twin Cities had filed a lawsuit after the compromise decision by the state’s department of labor and industry to require the sprinklers only in larger homes. The lawsuit was supported with briefs from the Builders Association of Minnesota and the National Association of Home Builders.

“After making a careful and searching inquiry of the record, we conclude that the 4,500-square-foot threshold for one-family dwellings is arbitrary and not supported by substantial evidence in the record,” the court said.

In its decision, the court cited the testimony of the state fire marshal, who said he supported mandating sprinklers in all homes — and the lack of evidence that “phasing in” sprinkler system requirements from larger homes to smaller ones was an effective balance of safety and cost.

The state did not “provide support for the implicit determination that a one-family dwelling over 4,500 square feet is the tipping point at which the life-safety benefits of sprinkler systems outweigh the costs. Why is it not 4,000 square feet or 3,000 or 5,000? Respondent has not provided us with an answer to that question,” the court said.

California and Maryland are now the only states that require fire sprinkler systems to be installed in all one- and two-family homes and townhouses. Since the mandate first became part of the model international residential code, more than 40 states have either modified the code to make them optional or passed legislation rejecting mandates.

The National Association of Home Builders continues to work with affiliated local and state Home Builders Associations that promote the continued use of smoke alarms: Ensuring every home in in the United States had at least one working smoke alarm would save about 890 lives each year, benefitting low-income families living in older housing stock and not just those who can afford a new home with fire sprinklers.

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