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Acou-ply: An insulative noise-dampening multi-functional panel

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    Johannes Schneider (1), Delaney Boyd (2)

    (1) Dipl. Ing.(bau), Ph.D. candidate in Civil Engineering at University of British Columbia
    (2) B.Sc., M.E.Des., Ph.D. candidate in Environmental Design at University of Calgary

    Given the common use of conventional plywood for floor and wall sheathing, it is an all-toocommon phenomenon to hear the klip-klop of shoes radiating through from floors above, or to heavily apply wall insulation, especially over gaps between boards, to ward off the cold.
    While plywood on its own provides almost no acoustic or thermal protection, creative
    hybridization of bio fibre materials with plywood has great potential to unify the advantages of wood products with varying densities, and elegantly improve traditional building construction.

    This design, coined Acou-ply (for acoustic plywood), comprises two layers of plywood with a 40-mm soft wood fibre core. Increasing in popularity in Europe, soft wood fibre boards, such as marketed by GUTEX (λ-value of 0.043 W/mK), are bio materials with excellent noisedampening and insulating properties. For this design, the soft core is sandwiched by glued plywood layersto create a composite board, which can be applied as a floor board over joists or on the outside of timber frame walls.

    The three layers within each board are slightly offset, creating a strong, stepped panel
    interface that eliminates any gaps from top to bottom. This continuous and closed sheathing layer is further augmented through use of tongue and groove connections on the plywood ends glued upon installation. A key advantage of this gapless connection design is that the boards can be screwed in place regardless of the joist or stud spacing. Heightened acoustic dampening is achieved by ensuring that the screws pass entirely through the top layer of plywood, thereby preventing any sound bridging along the fasteners. As well, sound transmission is interrupted by removing the top two layers of the floor boards at points where the timber framing of interior walls attaches to the floors(therefore, contact is made with only the bottom layer of plywood).
    [starrater tpl=44 size=’24’]
    Related links for the soft wood fibre material:
    Gutex Thermosafe-nf, Thermoflat, Thermofloor
    Pavatherm, Pavaflex


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