V25 is a prefabricated vapour barrier made of APP-modified bitumen, designed to be integrated as the first layer in the waterproofing assembly of flat roofs, between the substrate and the thermal insulation. Reinforced with a glass fibre reinforcement, which provides good dimensional stability and good heat resistance, it effectively limits the migration of water vapour into the waterproofing assembly. Both faces are coated with a heat-fusible HDPE film, allowing two installation methods: torch welding or cold bonding with a specific bituminous adhesive.
Intended exclusively for use as a vapour barrier, V25 is laid as the first layer on the substrate, before the installation of the thermal insulation and the main waterproofing membrane. It is suited to flat roofs with integrated thermal insulation, in residential, industrial and commercial buildings, in new construction as well as in refurbishment. Its low mass per unit area and reduced thickness make it a lightweight solution that is easy to handle and unroll on site, and compatible with common thermal insulation materials.
Installation is carried out on a clean, dry and stable substrate: with a suitable bituminous primer for torch welding, or with a specific bituminous adhesive for cold bonding. Laps must be carefully welded or bonded to ensure the continuity of the vapour barrier and avoid any vapour bridge, with particular attention paid to critical details.
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