With the exception of metal roofs, a total roof replacement usually is necessary when the roof is between twenty and thirty years old. If you are not sure how old your roof is, having a roofing contractor inspect it to determine how many years your roof probably has left before it needs a complete replacement might be a good plan. If your roof needs to be replaced now, here are some things you should prepare for that your roofer might discover while he/she is busily ripping off the roof.
Rot—Dry or Wet
If you do not make it a habit to go up into your attic for anything, you would not know how rotten the roof is. It can be seen quite well when you are in your attic, but not so much when you are standing on the roof itself. Wet rot looks like a soggy, sawdusty mess and is easily scraped into wet wood pulp just by dragging a screwdriver over it. Dry rot is a little less obvious, but if you hit the underside of a board and it turns into a powdered mess on the floor of your attic, you have dry rot. As your roofer begins to peel off layers of the old roof, he/she may uncover these problems from above. If that happens, most of the roof will have to be removed, replaced, and restored.
Wood Pests
Wood pests that quickly follow rot of any kind include carpenter ants, termites, and even cockroaches. Unfortunately, "waking" these pests up by pulling off the roof may cause some of them to head into your home's walls. The roofer cannot control that beyond throwing everything that is infested into a dumpster and hauling it away. Before putting a new roof on the house, you might want to call pest control to treat the house for whatever pests were uncovered during this roofing process. You do not want the bugs burrowing into and through the new roof!
Holes
Holes in your roof are not uncommon. They might have been there for a very long time. They might have been caused by hail damage, or squirrels and rodents might have found a little nook and broken through. This happens most often around old chimneys, but it can happen near the eaves as well. Since you are having the roof replaced anyway, you can take comfort in knowing that these holes will not be there when the job is finished.
To learn more, check out websites like http://www.allamericanroofing.com.