Most likely, this is the first thing you should assess. Is your roof old? Usually, a roof is referred to as old if its over 10 years old. On the other hand, when it comes to asphalt shingle roofs, then the durability is a bit higher in the sense that they can last between 20 and 25 years. Still, this isn't a rule of thumb, as there are several elements in Houston, TX, that could influence the durability of the roof.
One aspect is represented by the weather conditions in the area. In addition to that, in case the roof has been installed over an older roof, its durability might also be compromised.