Should you repair your roof? If your roof has a few minor leaks or minimal damage and was installed recently, then a quick repair may be suitable. But if the roof is 20 years old and has significant damage and several leaks, a complete roof repair will be in order.
If you are a novice in roof repairs or construction, it's best to leave the work up to the professionals. But if you have residential experience shingling a roof, you will likely be up to the task, but anything beyond asphalt shingles may be more complicated than it seems. Provided your roof's plywood substrate is not damaged or taking on moisture, a roof patch may be quick and simple.
Before going headfirst into the repairs, make sure to investigate the resources at your disposal. The old saying, "measure twice, cut once" applies here. Check online for how-to videos and do-it-yourself blogs to get some background knowledge to add to what you already know. Some things to consider as you do some initial research is finding what's existing. You will want to know if there is asphalt roofing felt paper over the substrate and if there is self-adhered ice and water shield present. Is the missing shingle at an edge of the roof? If so, check if the drip edge also needs to be replaced.
Also, check the existing roof for what type of fasteners are used and what type of shingle was installed. There are 3 typical shingle types: 3-tab, dimensional, and luxury. The 3-tab shingle is very common because it's the most inexpensive and can last a couple of decades. Dimensional shingles are multi-layered and last longer. Luxury shingles are intended to mimic slate or cedar shake roofs and are twice as heavy as the 3-tab type. Make sure to pick the right type to match your roof.
Another valuable resource is your local retailer. You can ask them for advice on how to go about the job. Retail stores will have roof sealant, roof cement, roofing fabric, and shingles for patching purposes. Good retailers will have someone on staff that can at least point you in the right direction or tell you if you're in over your head.
If your shingled roof needs a complete overhaul, then you need to take more into consideration. If there are multiple leaks, chances are that the roofing fabric is torn or missing. This added layer protects the plywood substrate from moisture. If there is damage to the substrate, you may want to replace entire sheets of plywood. Doing this makes the job more dangerous and intensive. At this point, it is wise to evaluate the scope of the job and consider if it's worth the cost and time to hire a roofer for the job.
There are several other factors that could influence whether you repair or replace your roof. If you're uncertain of your circumstances, ask a roofer to inspect your roof and provide you with a quote for their services.