Watertight
The roof was coated with two layers of bituminous felt and all joints were sealed with hot tar. Almost 100m2 of felt was used for a 30m2 roof. This is a work for professionals because of the high risk of burning down the whole place. Please notice the fire extinguisher on the lower right hand corner of the picture.
Antti Toivola on the left, Sami (the roof specialist) on the right.