Elastomeric paint is specially designed for masonry materials. It can fill in cracks up to 1/16-inch thick. It's expandable, so it hides any future hairline cracks. If you have cracks larger than 1/16 inch, fill them with elastromeric caulk, not standard caulk. Elastomeric paint also helps keep moisture out, preventing hairline cracks from getting worse. It's thicker than normal paint but can be applied the same. When dry, it has a rubber-like feel to it, although it looks like normal paint.
Elastomeric Color Choices
Be careful about how dark you tint elastomeric paint. Darker colors have a tendency to take on a chalky appearance when exposed to bright sun over extended periods. One solution to this problem is to paint over the elastomeric paint with a standard latex paint. Just be sure to apply it in heavy coats. With this method, you may need to touch up cracks as they appear through the latex topcoat.
Many different types of masonry paint are available, including waterproof and non-waterproof. Because it's the foundation of your home, waterproof masonry paint is the best choice. Waterproof masonry paint allows humidity to pass through it but not liquid water. This allows moisture inside the wall to evaporate but prevents rain or melting snow from getting through the foundation. Do not use a primer with masonry paint; this hinders the benefits of using it in the first place.
Masonry Primer and Latex Paint
Another way to paint a foundation is with a masonry primer and a latex paint topcoat. This may be a good option if your foundation stays relatively dry. Do not use a standard primer. Masonry primers have special properties that keep water out but allow moisture to evaporate, similar to masonry paint. When you're ready to apply the topcoat, use a high-quality, outdoor latex paint.