If you have been stuck behind a concrete mixer on Denny Way, or watched another apartment block inch upward in Ballard, you already understand Seattle’s housing problem. What you may not know is that a faster, cheaper and cleaner way to build those apartments already exists and that Washington’s own forests are sitting right there waiting to provide it. The building materials used are called mass timber, which is basically an engineered wood product consisting of wood sheets that have been glued together under high pressure to produce panels and beams of comparable strength-to-weight ratio when compared to steel and concrete. Cross-laminated timber is one such example of mass timber. This is not two-by-fours that are used in constructing a ranch-style house in the suburbs. Precut CLT panels simply need assembling at the building site. Mid-rise buildings do not cause the same chaos during construction. It is more like snapping together giant Lego pieces.…