In the beautiful area around Östersund this light weight I-beam structural building was produced in Norrlands trähus factory and then erected in two storeys, finished in 2022. The building fulfils the Swedish highest requirements (sound class A), in acoustic figures, DnT,w+C50-3150 ≥ 60 dB and L´nT,w+CI,50-2500 ≤ 48 dB. Our mission has been to develop the system for Masonite Beams (www.masonitebeams.se) over a long-time span and then to specifically adapt it to this building. Hence, we have carried out design of the system, calculated expected values of sound insulation for the structural components and flanking transmission through junctions, and finally to carry out verification measurements. The builder was Trångsvikens bygg in Östersund.