Abstract: A process for the preparation of a water-impervious surface coating on a substrate comprising applying to the substrate a layer of an aqueous bitumen emulsion containing, based on dry matter, 5-55% by weight of an acrylic prepolymer, 1-15% by weight of an air-drying alkyd resin, 40-80% by weight of bitumen, and optionally up to 5% by weight of additives, applying to this layer a glass fibre layer, and subsequently applying to the glass fibre layer at least one layer of water-based paint.A considerable saving in labor and time is obtained by the process and the coating obtained has an increased water vapor diffusion resistance.

Abstract: A hollow building element of a plastics material comprises an upper wall, a lower wall, a pair of opposite side walls interconnecting the lateral edges of the upper and lower walls, a joining member in the form of a cylindrical, slotted, downwardly open flange provided at the upper edges of each side wall, the lower end of a side wall being integrally connected to an anchoring element for anchoring the building element to a support and the lower end of the opposite side wall being integrally connected to a guide member adapted to engage the anchoring member of an adjacent building element so as to maintain the lower ends of two adjacent side walls in spaced relationship and so as to form a tight connection between such elements.

Abstract: In a roof or wall structure comprising ablong plates having lateral edge portions in the form of partially open cylindrical flanges and in which a flange of one plate is snap locked over a flange of an adjacent plate there is provided rigid beams having at each lateral edge a flange which flanges are snap locked to cylindrical flanges of adjacent oblong plates.