BOSTON — Jack Treanor offers up a modest proposal: Sextuple deckas. …It turns out the Boston Planning & Development Agency (BPDA) and local architects have been putting serious thought into the use of “mass timber”. …They say that not only would allow for even larger or taller structures the current cookie-cutter wood “stick” construction atop steel “podiums” that are the norm for five- and six-story residential buildings in Boston, mass timber simply means dramatically lower carbon footprints than steel and concrete. Boston currently has one mass-timber building – a seven-story, 34-unit apartment building at 11 East Lenox St. in Roxbury. The BPDA now has a Mass Timber Accelerator program to try to spur more mass-timber buildings. Over the past couple of years, the BPDA and the Boston Society of Architects have given out $25,000 awards to architects considering the use of wooden construction.