MIDA Standard PVS3, 3 mm bitumen membrane for roof underlay — 15 m² roll

A roof layer that disappears after installation still has an important job. The underlay forms part of the waterproofing system and works with the covering above it. Choosing it well helps protect the interior with a carefully planned set of materials. For the owner of a garage or house, this benefit extends beyond the refurbishment itself: a well-designed roof should support everyday use of the rooms through the seasons ahead.

An underlay serves a defined purpose in a multilayer covering. Instead of treating every membrane as the same material, its reinforcement, bituminous compound and installation method can be matched to the substrate and cap sheet requirements. The carrier helps provide the necessary mechanical properties, while SBS-modified versions offer the flexibility specified for each product. The benefit comes from the components working together: the lower layer is prepared for its own role, giving the complete covering a clearer and more predictable construction.

This is particularly important in refurbishment, where the new material must suit the existing roof conditions. Different underlays are intended for particular substrates, including wood-based decks, concrete or suitably prepared thermal insulation. Selection in line with the documentation allows compatible layers to be assembled. The result remains hidden from the building user, but its purpose is specific: roof protection relies on a material chosen for the use of the entire roof area and the room beneath it, rather than on an arbitrary product.

The underlay’s surface finish is designed to work with the specified roofing layers.

Versions with different reinforcements allow the material to be matched to the roof design.

Flexible modified versions help account for temperature changes within the complete system.

The roll format allows a continuous layer to be planned over straightforward roof areas and suitable details.

Underlays are used in new coverings and appropriate refurbishment systems on houses, garages and outbuildings. In a store beneath a small roof, they help plan a water barrier as part of a complete build-up. On a residential building, they can work with a cap sheet above a heated space. The right product reconciles the needs of the substrate, insulation and covering without expecting one material to replace every layer. The benefit for the owner lies in assigning each material a role in which its properties are genuinely useful. This provides a sensible basis for a durable roof finish.

We supply underlays and help compare their intended uses with the planned roof covering. SteelProfil offers first- and second-grade materials, stock availability and numerous promotions. We combine competitive prices with the selection of available products suited to the substrate and subsequent layers, so the order reflects the actual scope of roofing work.