As many people know over time manufacturers will stop producing lines of products. This can be because of corporate buyouts or advances in technology. Even if your roof is older than 12 years old, your shingles and accessories on your roof are probably not being produced. This is problematic because if there’s damage of any kind there may be no compatible products for your roof repair. I like to use the example that you can not put Subaru ball bearings on a Ford F-250. They both have ball bearings but they utilize different products that have different sizes, shapes, and manufacturing processes.
IRC (International Residential codes) 904.2 Compatibility of Materials states, “Roof assemblies shall be of materials that are completable with each other and with the building or structure to which the materials are applied”. Meaning you can not put current GAF shingles on a roof that has a discontinued shingle. The reason is the new limited lifetime shingle technology and size. The old laminate shingles were bigger and utilized sealant in different locations. If you mix the two products there is a chance that the shingles will not seal properly. Then, you will be back where you started.
IRC (International Residential codes) 904.4 Product Identification states, “Roof covering materials shall be delivered in packages bearing the manufacturer identifying marks and approved testing agency labels required”. Meaning that if you are attempting to repair your roof, you may try and use any shingle that looks similar to your current ones. However that would mean you are violating the IRC. You need to have confirmation that the shingle on the roof is currently available before completing a repair.
IRC (International Residential codes) 908.5 Reinstallation of Materials states; “Any existing flashings, edgings, outlets, vents, or similar devices that are part of the assembly shall be replaced where rusted, damaged, or deteriorated”. IEBC (International Building Codes) 401.2 Compliance states; “the work shall not make the building less complying than it was before the repair was undertaken”. These codes are getting to the point that you can not repair roofs correctly using any old products. They have to be new materials (not damaged) and they have to ensure that the building is not less compliant with current building codes when completed.
During an attempted repair you also have to guard against damage that is sustained during the repair process. In many cases, a roof will be unrepairable simply because of the age and condition of the shingle. In that case, you are running the risk of your contractor doing more harm than good! If you have a roof that is 12+ years old and a contractor comes to do repairs to that roof there is a good chance that they installed a product that is not compatible with the current system.