When it's time for a new roof, you've got a lot of new choices these days, many of which will last more than 50 years. New engineered shingles are made to look like cedar or tile using recycled materials. Even metal roofs, the old standby for barns, have made a comeback with new colors, styles, and an unbeatable maintenance-free life expectancy.
Stir wallpaper paste for longer than suggested by the manufacturer to ensure that there are no lumps. A wooden dowel makes and ideal stirrer. Also stir the paste from time to time during wallpapering.