Roofing felt are several different types of bituminous membranes, which is often used as two-layer solutions with an underfelt at the bottom and a top felt more firmly at the upper part as a finished roof covering.

Underfelt on the TF-30

Underfelt on the finished roof insulation.

Roofing elements that held for slope can advantageously supply with 30 mm rigid roof insulation, and roofing felt and ready for shredding. In this form of construction saves one of the two procedures on the nonbuilding to lay the two layers of roofing felt. Overall, this is often a cheaper option than to lay wedged isolation and subsequent two layers of cardboard on the construction site. SkanDek using most often a type of under felt PF 3000th

Underfelt fixed to the trapezoidal plate.


Tight roof before laying roof insulation

For flat roof is SkanDek elements provided with an underfelt with welded overlays and mechanically attached to the trapezoidal steel plate. The roof elements must immediately later on shredded in the end and longitudinal joints so that the roof closed during the construction period.

As a conclusion, the contractor must interpret min. 30 mm rigid insulation, in-built fall towards the drain. The finished roof insulation is completed then with foil or roofing felt.


Bitumen is a popular and well-known material used since ancient times to seal include jars, houses, and ships, and water can’t dissolve it.

During the production of roof elements, they are tied up welding tests included,  part of SkanDek’s quality assurance. The mechanical fixings into the trapezoidal steel plate dimensioned according to the weather. The PF-3000 under felt as SkanDek uses reinforced with a polyester felt.


Roofing felt consists primarily of bitumen, which in turn consists of hydrocarbons. The other fillers in the roofing felt include sand, slag, polyester and slate (top felt). Bitumen derived from crude oil, but when hydrocarbons linked in the bitumen, does not contribute to increased CO2 emissions. In opposite to the oil which refined into fuel for internal combustion engines.

Roofing recycled. Immaculate bitumen residues can be melt again into new roofing felt, while others bitumen residues are recycled in road asphalt, reducing need for drilling new oil.

Modern roofing membranes have a life expectancy of up to 25 – 30 years.


Roofing membranes included in SkanDek’s ETA for CE marking.

Side photos

Underfelt on the TF-30, the corrugated steel plate mechanically attached.

Aller House on Copenhagen’s waterfront. Roof elements supplied with TF-30 and under felt and finally completed with metal roofs.

Shredding Underfelt in length joints, before laying of wedge-cut insulation.


Under felt on the TF-30, mechanically attached to the corrugated steel plate.

Aller house on Copenhagen’s waterfront. The roof elements were provided with TF-30 and the under felt, and finally finished with a metallic cover.

Shredding under felt with longitudinal joints, prior to the laying of kileskåren insulation.