Bitumikalvot

Bitumikalvot, or bitumen membranes, are thin sheets made from bitumen-based material used for waterproofing in construction and civil engineering. They are usually reinforced with fibers such as fiberglass or polyester, and may include a protective top layer, foil backing, or coating to enhance durability and weather resistance. Common variants are self-adhesive, cold-applied, and heat-activated (torch-on) membranes. Many formulations incorporate polymer modifications, notably APP (atactic polypropylene) or SBS (styrene-butadiene-styrene), to improve elasticity and temperature performance.

Manufacture and structure involve applying bitumen, often polymer-modified, onto a reinforcing carrier and then converting the material into sheet form. The sheets are produced in standard widths and lengths for site handling and installation. Joints are sealed by overlapping and either torching, self-adhesive bonding, or cold-seal methods, sometimes with seam tapes or sealants.

Applications include roofing and underlayment for pitched and flat roofs, waterproofing of basements and foundations, tunnels, podium decks, and other concrete or masonry structures. Bitumikalvot can function as primary waterproofing layers or as part of a multi-layer membrane system, typically protected by a ballast layer, protective sheet, or surface finish to resist UV exposure and mechanical wear.

Performance characteristics vary with formulation, substrate, climate, and installation quality. They generally offer good waterproofing, chemical resistance, and flexibility at low temperatures, but require protection from UV light and careful installation to avoid puncture or delamination. Lifespans commonly range from 15 to 30 years depending on conditions. Safety and environmental considerations include fumes during installation and end-of-life disposal of asphalt-based products.