Which way up is an Onduline sheet fixed?

Onduline roofing sheets are easily identifiable by the printed production quality control information applied up the last corrugation on the smooth grained topside.

Watch the video

The topside of the roof sheet is sprayed with a resin which helps to combat UV degradation. The colouring is a natural pigment, which is impregnated into the sheet, prior to the bitumen dip. This process ensures an equal colouring and means the colour cannot peel from the sheet.

The underside of the roof sheet has a rippled finish. This increases the surface area, enabling it to combat condensation. It will hold the moisture for as long as it can, until the airflow dissipates the liquid, by turning it back into vapour.