Windshield glass is a big investment, especially if you own a large or luxury vehicle, so you probably want to make sure it doesn't need replacing. If you live or work in an area where there is a higher chance of rocks flying around, such as a construction site or farm, then you'll probably want to make sure you're protected against an occasional hit from a stone at high speed. Fortunately, there are several extra ways to protect your windshield from being destroyed by flying rocks.
There are several brands of windshield films that are designed to protect against hard impacts from rocks and other debris. The principle is that the film provides an extra membrane that catches and repels impacts before they get deep enough to cause cracks. Rocks are supposed to just bounce off when they hit. Even if a rock manages to make contact, these films can help keep cracks from spreading, further making repair easier. They are also available in different tints to protect against the sun. Their downside is that they can cause visibility problems, such as creating wavy lines, if they're not installed correctly.
Spray or wipe-on coatings:
Spray or wipe-on coatings provide protection against a wide range of issues, including bugs, tar and salt, as well as small and large impacts from rocks. Like films, they add an extra protective layer in which rocks are supposed to bounce right off. Another advantage to these coatings is that they are claimed to boost visibility by reducing glare and resisting rain water. The downside to these coatings is that they sometimes wear off and need to be reapplied. In many cases, one coating treatment may cost almost as much as a new windshield, depending on your make and model, so multiple repeat coatings may not be cost-effective.
If neither of these options look like they will work out for you, then you may want to take to a professional windshield repair shop to see about windshield options. They may be able to install a thicker glass or a windshield with a slightly modified shape, but be aware that this may cause additional issues. Straying away from the manufacturer's recommendations too far can sometimes cause noise, fitting or visibility issues.
If you're having a problem with repeated rock impacts, or you think you're at a higher risk of them, talk to a professional before doing anything. Do not attempt to apply any coating or film to your windshield yourself, as these items have to be placed on a specific way for them to work without issues. Contact a company like Econo Glass Company for more information.