A well-installed roof made of quality materials can and will last for many decades without many problems, but there always comes a time when you have to start thinking about whether it´s worth it to repair, or just replace the roofing as a whole. Wind, rain, sunshine and snow all pose some amount of threat to your roof depending on how bad are they in your area, and no roof can withstand the elements forever. There can be many signs that indicate that the roof above your head is not as protective as it used to be. Broken or missing shingles are of course very straightforward, but water in the attic or on the top floor as well as stains on the ceiling and walls can be very good implications of a deeper problem.
Some damage on the roof does not necessarily mean that you have to replace the whole thing, only that it is time to call a professional who will be able to check and evaluate the condition of the roof. The inspector will tell you whether a repair is enough or is it time to replace the whole roofing. If the problems a recurring, though, it is usually advised that you think about a long-lasting solution, as repairs only delay the problems, do not solve them.
The costs of a roof repair and a roof replacement differ significantly of course. Repairing costs are impossible to be estimated, as the amount of the damage can vary greatly. We can make a better estimation of the costs of replacing though. It can be broken into three parts, the preparation (removing old, broken materials), the new materials (wood, tile, concrete, etc.) and the cost of labor. The third and the first one will usually cost the same for everyone (around 3-5 dollars per square foot), but the materials you choose (and the size of your house) will determine the real cost of the roof replacement.
Concrete and asphalt are usually the cheapest options, while wood can cost up to three times as much as those two. Therefore, depending on your choices and the parameters of your house, it will probably cost from 4000 to 6000 dollars for an average home, and will require 2-4 business days to be completed. If you also had skylight issues you want to be dealt with or want solar panels installed (or just their mounts to put panels on later), it will cost you more of course.
Things to Consider
It is strongly advised that you plan the beginning of the works a few weeks beforehand, especially in the case of a full replacement. Not only this kind of job needs proper preparation, it also needs dry weather and at least above freezing temperature (35°F or more) in order to create a really long-lasting effect. Try to look for usually dry periods of the year in your area, it doesn´t necessarily have to be in the summer, as long as the conditions are ideal.
Always make sure that after your roof is repaired or a new one is installed, the ventilation in your attic is ideal. Without ventilation, high humidity levels and warm temperature can damage the basis of the roofing, which causes the expected lifespan to be much lower. Keep in mind that there are many manufacturers who consider their warranties void if there is no proper ventilation in the attic, so this can be a really expensive mistake to make if by chance an accident happens to your new roofing.
When in doubt, you should always ask for some professional help. Contractors don´t charge large amounts for just evaluating the condition of the roof, so it is something you should do every now and then, especially if your roof is getting older.