During roof replacement, it is very important to consider the amount of time it has served a protective structure of your house. General recommendation for replacing roofs is mostly when the roof has reached more than 20 years of existence. There is a method that is viewed by many as a combination of roof repair and replacement. This is when a new layer of roof is put on top of the existing roof structure. This method perfectly fixes leaks and holes, concealing them under the layer of new roof sheet or shingles that will create an impression that it is an entire replacement when viewed from atop.