DELTA®-BiCo Technology

Sarking sheets with the latest cloth backing

The cloth layers for our DELTA® sarking sheets are made with the latest BiCo core-mantle technology. Cloth backings ensure the mechanical stability – or tear strength – of roofing sheets. Depending on the manufacturing technology employed and the square weight of the cloth, sarking sheets may be made ‘fall-though safe’, for example.

BiCo is composed from the Latin prefix bi- for ‘two’ and Co for component. Fibres are produced in a special manufacturing process. Unlike conventional fibres, BiCo fibres consist of two raw-material components, one in the core and one in the mantle. This permits stabilising the fibres exactly in the right spots and placing them more closely together.

An example:
Our BiCo fibres are made as continuous filaments; therefore, the cloth does not contain fibre whiskers. Looking at a square metre we see that each individual fibre in that area is up to 120 linear metres long. In a 70-gram cloth for one of our DELTA® roofing sheets, each square metre contains a total fibre length of c. 389,000 metres. In other words: in a roll of DELTA® sarking sheet, the fibres on one of the sheet’s faces will have a total length of more then 29,000km! Depending on the DELTA®-AMS technology and on the reinforcement cloth used, the fibres may be more than 62,000km long! If we add to that our special material-conservative production processes we have an end product that is optimally adjusted to its intended application in a roof.

The advantages of products incorporating the BiCo technology


The BiCo technology enables us to impart new and advantageous properties to our spunbonds. What we get is a high-performance fibre which may be adapted to the specific applications of the end product by including special additives in the core and mantle. Advantages include increased fibre density, greater tensile strength, and higher UV resistance, which ultimately increase the durability/service life of the roofing sheets.

Energy-saving sarking and waterproofing sheet. Keeps cold outside air in check, thus reducing the heating-energy consumption by up to 9%

Extremely tear-resistant step-through safe sarking and waterproofing roofing underlay. Resistance against hail impact up to 130 km/ph

DELTA MAXX - safe roof

Fire-retardant sarking and waterproofing sheet. Absolutely waterproof and highly tear-resistant – high guaranteed safety when using ladders on battens.

DELTA FOXX top roof

Soft sheathing and sarking sheet for extreme weather conditions and sheathed roofs. With lotus effect (water drips off particularly easily)

Soft sheathing and sarking sheet for fully insulated pitched roofs.With integrated adhesive strips along both edges.Available without adhesive strips as DELTA®-VENT S

Sarking sheet for unsheathed pitched roofs. With integrated adhesive strips along both edges. May be used as a waterproofing sheet in the DELTA®-VENT N version without adhesive strips


Universal soft sheathing and sarking sheet consisting of a tear-resistant 4-ply composite for fully insulated pitched roofs with or without hard sheathing

The clever combination for protecting pitched roofs. 3-ply soft sheathing and sarking sheet. Innovative adhesive zones along both edges.


Structured separation layer for vented and unvented pitched roofs with metal covering. Perfect protection from corrosion and moisture