One of the biggest problems was small foundation cracks is that they can actually get bigger. The small ones usually are not that big of a problem, however once they start to get larger or continue growing, now is when you have a big problem with your building foundation.
Go around your home building and examine the foundation for any cracks, write their location down on a piece of paper and if possible take a couple of pictures so that you can re-examine the older pictures when you inspect your building foundations in the future .
If you notice that these cracks are getting larger, it would not be a bad idea to contact a contractor who is familiar with building foundation problems in your area. These contractors should be able to answer all of your questions and provide you with a good solution to repairing your building foundation.
If your small foundation cracks are not growing or getting larger, you probably are not going to need to worry about your building foundation. Hairline cracks are common in almost everything made from concrete. Concrete sidewalks, driveways, footings and building foundations crack and that's a fact of life, the only problem is we do not want these cracks to become too big or we could find ourselves with building foundation problems.
I forgot to mention what I would consider a small crack to be. It would help if you knew what you were looking at while you were inspecting your building foundation. If you can not stick a penny into the crack, you probably do not have any problems. This is what I would consider a small crack, anything less than the width of a penny.
If you can stick your finger into the crack, there's a good chance that you have major foundation settlements problems and this should be addressed as soon as possible. Any cracks larger than one quarter of an inch in width should be measured and monitored closely in the near future for any movement or expansion.