Green Building, Old school: Scandinavian Sod

“Green Building” usually conjures images of new technologies, energy-savings diagrams, and a plethora of mechanical products. But what about the old school type of green building: the tried-and-true, age-tested building methods that hark from an era which predates energy crises and carbon awareness…or, even better, an era that predates modernity altogether? What can we learn from techy-new-age green building’s long lost cousin, vernacular architecture? Here is a look at one old school example of green building technology (which also happens to be a precursor to today’s green roof): the Scandinavian sod roof.

There are examples of Scandinavian sod roofs dating back to…well…prehistory. During the Viking and Middle Ages, sod roofs were the norm, at least for residential buildings, and it wasn’t until well into the 19th century that industrial roofing materials such as corrugated iron began to supersede the dominance of sod.

Traditionally, a Scandinavian Sod roof was built with sloping wood boards, overlaid with several layers of birch bark, and then covered with two layers of sod. The birch bark acted as a water- and soil-resistant layer, lasting an average of 30 years before needing to be replaced. The bottom layer of sod was installed grass-side-down, allowing the wilted grass to act as a drainage later; the second layer was installed grass-side-up, giving the sod roof its anticipated grassy appearance. The pieces of sod were typically harvested from nearby pasture land, cut into manageable pieces , and laid over the birch bark, holding it in place. The benefits of the sod/birch bark roof were remarkable – good insulation in cold weather, reasonably water-tight, and a heavy load to compress the walls of the structure underneath Additionally, the roof was constructed from materials that were free, locally available, and relatively easy to work with. Doesn't get much greener than that.

A new spin on sod

The TM9 Green Roof Tile, created by Toyota Roof Gardens, a subsidiary of the car-manufacturing-giant, might be called a contemporary reinterpretation of the old fashioned sod roof. These lightweight tiles, 20 inches square and 2 inches thick, can be installed on an existing roof without necessitating additional structural support. They, of course, don’t have all the benefits of a traditional sod roof – they aren’t free or locally available – but they do offer an easy way to invest in green building.