Mida Self Base GVS3 bituminous underlay sheet, 2.7 mm, 10 m²

The durability of a roof covering also depends on layers hidden after installation. An underlay forms part of the designed waterproofing system and provides a base for the next layer. Its selection affects the usefulness of the whole roof, making it a sensible element of both new-build and refurbishment budgets. It combines the properties of a roll material with a solution suited to the substrate, fixing method and expected movement of the roof assembly.

In a multilayer system, the underlay works with the cap sheet to provide the planned protection against water. The reinforcement gives it defined strength, while the bituminous compound supplies its waterproofing properties. Materials can therefore be selected by function rather than by the similar appearance of the rolls. For the client, this produces a clearer cost plan in which every layer has a purpose. Coordinating both layers helps make use of the complete system’s properties and estimate the full cost of protection.

SBS-modified products provide flexibility useful in coverings exposed to temperature changes. An appropriate reinforcement helps match the membrane’s behaviour to the substrate and service conditions. This matters on roofs of buildings expected to retain their use over many years, such as garages, pavilions or production support facilities. The client can specify a material suited to the particular system from the outset, reducing the risk of later changes caused by incompatible layers.

Underlays come in versions intended for different fixing methods and substrates. This allows a solution to be selected for a concrete deck, timber structure or suitable insulation layer in accordance with the product documentation. The market also offers self-adhesive versions for systems that specify this connection. The choice lets the installer prepare an approach suited to the building and gives the owner a clear comparison of the complete scope of work.

Roll material makes it easier to form a continuous layer across large areas and around details. It is suitable for new coverings and appropriately planned renovations. On larger buildings, compatible materials can be assembled for successive roof sections while maintaining the same standard of workmanship. An underlay also separates the functions of individual products: the concealed layer performs its task, while the outer sheet receives the finish required for weather exposure. This division helps direct the budget towards the right properties of each material. On repeat projects, the same build-up also simplifies subsequent orders. The installer receives a clearly specified set, and the owner can compare the cost of the same method over different areas.

We stock underlays and a wide range of first- and second-grade materials, with products available for immediate supply. At SteelProfil, numerous promotions and attractive prices help you purchase a complete roofing package. We help compare products for your chosen system. Tell us the substrate type and scope of work, and we will prepare a proposal.