A thorough exterior inspection should be the first step in making a decision on whether to replace or repair. A frequent culprit is damaged or missing shingles.  High winds as well as improper installation can cause shingles to become displaced. Some regions of the country (especially in the southeast) may have shingles permeated by algae or fungus which can lead to damage of the roof decking material. Damaged or improperly installed flashing around chimneys, skylights, and vents may also be a source of potential problems. Checking rain gutters for granules and bits of rotten wood may also indicate trouble. It should be mentioned that loose granules found after application of new roofing should not alarm you, this is normal; on older roofs this indicates the need for replacement. Buckling of shingles may be a result of improperly installed felt, or shifting of the roof deck. Though there are other things to look for while inspecting the exterior of your roof an interior inspection is most likely to be the deciding factor when asking “Do I need a new roof?”

 An interior inspection can be instrumental in deciding whether or not to go with a new roof. Deteriorated decking or decking that sags between the rafters (sometimes visible during an exterior inspection) is a sure sign that superficial repairs such as replacing a few shingles will not suffice. If both the decking and rafters are badly damaged it is time to consider a new roof. Re-roofing (placing a new roof over the existing one) when there is extensive damage to rafters and/or decking can lead to major future problems, even roof collapse in areas with heavy snow.

Signs of leaking found in the attic indicated by dark spots in the wood are another common problem especially around vents, chimneys, and other holes in the roof. Spots found in the wood should be tested to determine whether they are a result of old problems that have been fixed or newer ones in need of repair. Wet or soft spots suggest a current problem whereas dry and hard spots are more than likely old problems that have been previously repaired. Water stains or sagging ceilings are usually indicative of current problems such as a leak or poor ventilation which can cause condensation and may result in water damage. These are only a few of the problems which can occur. It is extremely important to contact a professional if for any reason you believe your roof is in need of replacement or repair. Also, check the link below for more detailed information about roofing inspection. And remember that early detection by regular inspections is by far the best plan to avoid expensive repairs.  Get more info at http://roofing.owenscorning.com/homeowner/thingsyoushouldknow/needaroof.aspx 

Article Source: http://www.roofer911.com