There are several points to consider when trying to make this decision and keep in mind that no two roofs are the same. So while there are general guidelines you can follow to help you decide, keep in mind that you know your roof the best and whether there are other considerations that you should make such as if you know that the roof was not installed properly.
o If more then 30 percent of the entire roof is damaged, or if there is extensive moisture damage to either the existing roofing layer or the structural deck, you should consider replacing the entire roof.
o If your roof damage occurred as a result of a storm such as a tornado or hurricane, then you should certainly consider replacing the entire roof. In these situations, there are is often damage that you cannot see and it’s important to go ahead and replace the roof. Safety for you and your family is the most important factor.
o Is there a pre- existing condition on your roof that would make it beneficial to go with a full roof replacement?
Consider replacement if:
o You think your roof has a faulty design
o Improper material was used while constructing the roof
o There were past problems with mold or algae growth
Factors to consider:
o Interior Walls– Two sure signs of major roof repair are if the walls and ceilings in your home have moisture marks and if the paint on your walls and ceilings are peeling.
o Torn or Missing Shingles– Torn or missing shingles could be caused by many variables from heavy sun to tree branches being improperly removed from the roof. Sometimes torn or missing shingles are a sign of a simple roof repair but there are times that it is the clue that there are more serious roof issues. It’s always important to consult with a skilled roofing contractor who can help you determine the severity of the problem.
o Roof Layers– If you have more than 3 layers on your roof and are again experiencing problems then it’s time to replace.
o Roof Age– If you have an asphalt shingled roof of good quality material and installation than it should last between 15-20 years. If your roof is over 12 years and experiencing roof leaks associated with other roofing problems too then you should seriously consider replacement.