National Geographic : 2012 Dec
Hail, Timber In Nara, Japan, a 122-foot-tall wooden pagoda has stood for more than 1,300 years. Very few modern structures like it exist, largely due to fire-safety concerns and building codes that limit the height of timber structures. Canadian architect Michael Green aims to change that with a proposed wooden skyscraper up to 30 stories high in Vancouver. He explains that giant panels of laminated wood known as mass timber are more fire-resistant than typical two-by-fours, just as logs are harder to ignite than kindling. The bigger advantage? The production of concrete and steel emits high levels of carbon dioxide, whereas wooden buildings store carbon that would other- wise be released when trees decay or burn. London already has a nine-story mass-timber apartment building, and a 16-story wooden skyscraper is slated for Kirkenes, Norway. Green's ultimate ambition for timber towers is even loftier: provide affordable housing for people living in slums. ---Alex Hoyt NEXT | CITY SOLUTIONS Mass Timber Instead of traditional lumber, mass timber uses laminated boards and plywood made of sustainably grown lower- grade wood---such as fast-growing birch and aspen---that wouldn't normally be suitable for commercial use. Laminated Panels Based on tree species and regional production, several types of panels can be combined for floors and walls or used alone for a whole building. Glulam Small-scale lumber glued together creates very strong and fire-resistant beams and columns.