Roofing underlay Primaglas G200S4, 4.2 mm — roll of 10 m²

A bitumen underlay is an important component of a multilayer roof covering. It works with the cap sheet to form a continuous waterproofing system suited to the substrate. At SteelProfil, we help select an underlay for a new roof or refurbishment, considering its reinforcement, flexibility and the fixing method specified for the particular product.

Selecting a membrane starts with checking the complete roof build-up. A sheet installed on concrete may require a different fixing method from one used on a wood-based deck or insulation. Compatibility with the cap sheet and other system components also matters. Buying an underlay therefore becomes part of planning the complete roof assembly, rather than a separate decision based solely on the price of a roll.

• A suitable underlay supports continuous waterproofing in a multilayer roof covering.
• The right reinforcement and bituminous compound allow the membrane properties to be matched to a particular substrate.
• Choosing the specified fixing method helps match the material to the planned roofing process.

Underlays are available in SBS-modified versions whose flexibility is defined by the individual product specifications. The reinforcement affects how the sheet behaves under loads and deformation. Comparisons should focus on the properties needed for the proposed roof system, including surface preparation and joints between adjacent strips. A well-matched material helps the roofer use a consistent installation method across the roof.

During refurbishment, an underlay can form part of a new build-up on a properly prepared surface. The condition of the existing layers and the chosen technical solution determine the procedure. In a new building, connections at parapets, outlets and other details can instead be planned from the outset. Allow for these areas when ordering, as they require additional material and compatible accessories. Considering details at this stage helps complete the delivery without splitting the purchase into separate stages.

At SteelProfil, we help calculate the number of rolls from the roof area, overlaps and upstands. Our wider building materials range includes first- and second-grade panels and sheet metal, with selected items available from stock. For the underlay, we identify the specific product and confirm availability so that the offer meets the installer’s requirements. You can also include the cap sheet and other components specified for the roofing system.

Numerous special offers and favourable prices help you plan waterproofing expenditure sensibly. A good purchase connects the underlay with the rest of the covering, so we will gladly compare suitable options with you in one quotation. Information about the substrate and planned installation method helps us prepare it. You receive material with a clearly defined purpose and a quantity calculated for the whole job, including areas requiring particular care.