Apply the cut felt to either side of the roof pulling it tight so that it lies flat before nailing it at around 10cm intervals along the length of the roof, just below the apex. You can hammer in the nails along the bottom edge of the roof at wider intervals – around one every 30cm. Once you’ve secured the side panels in place, add the top section to the ridge and fix it using high performance felt adhesive applied with a paint brush, then nail it at the lower edge at 5cm intervals.