Technonicol MIDA Standard PVS3 underlay: 15 m², 3 mm

Before installing the roof’s top layer, a suitable underlay must be prepared. Its compatibility is important to the consistency of the complete covering. Bitumen underlays help form the lower waterproofing layer on new and refurbished buildings. At SteelProfil, we select a product to suit the substrate, installation method and material that will be laid above it.

The underlay functions within a designed multilayer covering. It provides the layer beneath the next membrane and contributes to protecting the roof against water. Selection must take account of compatibility throughout the system. This establishes a clear sequence of work and prepares a surface that meets the requirements of the next stage. A properly specified underlay is particularly useful on a roof with many penetrations: the necessary waterproofing sections can be formed within the same predetermined build-up.

Available membranes differ in reinforcement, bitumen type and intended use. Selected products can be used on concrete, wood-based substrates or in insulated roof systems. The fixing method follows the documentation for the particular product and substrate. We help match the material so the roofer can begin work with an appropriately specified underlay layer.

For a garage or extension, the underlay can be planned together with the cap sheet from the outset. On a larger roof, this also helps divide the work into areas and organise deliveries. A well-chosen membrane allows waterproofing to proceed systematically, instead of selecting the next products during installation. The entire set of materials then follows one common plan.

On a building undergoing modernisation, the condition of the existing surface matters. Once the refurbishment method has been established, an underlay suited to the proposed build-up can be chosen. Include connections to walls, parapets and drainage components. This prepares the new layer for details that will subsequently be covered by the cap sheet.

Underlays may have other waterproofing applications where the particular product documentation allows them. Selection therefore starts with the location of use rather than the name alone. For a roof, we discuss the complete build-up; for another building element, its service conditions. This is a straightforward way to obtain a solution suited to the individual project.

We offer numerous promotions and favourable prices on roofing materials. Selected products are available from stock, and the wider sheet metal and insulation range includes first and second grade. We select underlays according to their specifications and purpose. Together, we also check the products needed for substrate preparation and installation of the next layer.

For a quotation, include the roof area, substrate and planned upstands. This allows the number of rolls to be calculated with the joints included. A suitable underlay makes it easier to complete the covering and keep the work organised. Plan it together with the cap sheet so that the roof is designed as a compatible whole from the start.