A Velux loft conversion does not alter the roofline. It uses Velux windows that allow the natural sunlight to shine through into the room. This type of loft conversion is the most cost-effective and the least disruptive method of creating additional space in the loft of your home.
Since the external roofline of the property is not altered, there are no finishes to consider with this type of loft conversion. After the job is complete, the only visual change to your roof is that it now has Velux windows.
You can choose to have the Velux windows either slated or tiled in using the existing roof tiles or slates, so that they appear as if they have always been there.