Grindverk

     Thanks to Kjell Heggstad for pointing out that grindverk is a traditional building technique that dates back to the Viking Era. The photos below are of a structure built by Thomas Hustad.

     Though planks may be of any old wood (usually fir or spruce), the curved structural members have to be of birch. The builder has to somehow procure trees that have grown into the desired shape in order to make these structural pieces. Fastening is done with birch dowels that are first dried, then inserted into their holes, and then moistened so that they swell up again to their normal size and make a tight connection.

This particular structure is a canopy for some picnic tables in a scenic spot in Sæbø. 

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     Of course, what would a grindverk structure be without a torvtak (turf roof)? The torvtak is still widely used in Norway, especially on farms and leisure structures (e.g. ski cabins). Some small tourist hotels feature units with turf roofs.

     Today, torvtak builders make use of modern underlayment materials that extend the lifetime of a roof from about 20 years (for a traditional torvtak that uses no modern materials) to as long as 50 years. True to the spirit of the grindverk, the torvtak in this photo has been constructed in the old style, with birch bark underlayment.

Birch bark has also been used to insulate critical areas from water damage.