4.2 mm bitumen roofing underlay Primaglas G200S4 — 10 m²

A sound base for a roof covering is hidden once the work is complete, but it matters to the performance of the whole roof. The underlay provides a layer beneath the remaining waterproofing components. At SteelProfil, we help match it to the particular substrate and installation method, keeping subsequent stages within a consistent plan. It is needed both for new roofs and for properly designed refurbishment of existing roof areas.

Underlays are designed for a particular roof build-up, so their construction and fixing methods vary. Torch-on, self-adhesive and mechanically fixed versions are available, always subject to the product documentation. The right choice helps connect the substrate with the next layer. We compare available materials so their intended use matches the roof design and the resulting quotation is clear to the installer.

The reinforcement and bituminous compound influence the membrane’s mechanical properties and behaviour. Site conditions and compatibility with the cap sheet are also important. A well-specified system lets the team concentrate on carefully forming joints, upstands and overlaps. For the client, this means a more organised project and the ability to plan materials before the roofers arrive. The underlay has a defined role and cannot simply replace a product intended for permanent exposure to the weather.

In practice, the condition of the surface receiving the membrane is particularly important. An even, properly prepared substrate helps form a continuous layer using the chosen method. Before purchasing, establish details at parapets, chimneys and other penetrations. Material consumption can then include areas beyond the roof’s basic plan area. This preparation supports efficient installation and continuity between successive waterproofing layers.

SteelProfil offers numerous promotions and favourable prices for roofing work. Selected products are available from stock, making it easier to align purchasing with the installer’s schedule. First- and second-grade sheet metal, panels and insulation broaden the purchasing options, while underlays are selected by their specifications and intended application. You can also discuss the cap sheet and other materials needed to complete the project.

A properly specified underlay lets you proceed with roofing using materials prepared to work together. Tell us about the roof type, substrate and chosen installation method so that suitable solutions can be compared. We help match quantities and available variants to the work schedule. Although the underlay disappears beneath the next layer, selecting it is an important part of the order: it contributes to protection that the building owner relies on through changing weather.