Harriet Tubman House | 566 Columbus Avenue | South End

stick n move

Senior Member
Oct 14, 2009
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It's actually a reference to where the materials are addressed in building code. The height can vary, but the distinguishing feature regards use of type 1 materials on the first floor, and type 5 materials for additional floors. I do think there is a limit to just how many type 5 floors you can add, though local variances probably vary on this.
“The one-plus-five style of buildings exploded in popularity in the 2010s, following a 2009 revision to the United States-based International Building Code, which allowed up to five stories of wood-framed construction.[4] The mid-rise buildings are normally constructed with four or five wood-frame stories above a concrete podium (usually for retail or resident amenity space).”

“most of these structures are what’s known as “5 over 1” or “one-plus-five”: wood-framed construction, which contain apartments and is known as Type 5 in the International Building Code, over a concrete base, which usually contains retail or commercial space, or parking structures, known as Type 1.”