If you're thinking of buying vacant land, you might have that plot surveyed, to ensure you know its actual, legal boundaries, and to find any easements, buried lines, and other such potential hazards on that land. However, if you already own property, it can still be good to have it surveyed on occasion. Note when and why you might hire a land surveyor for your residential property, and how their services can benefit and protect you.
After a natural disaster
Many property owners use natural features on their property as visual boundaries; this might include a boulder, stream, and so on. Certain natural disasters might shift those features and actually move them out of place; a flood can soften the soil under a boulder so that it moves out of position, or overwhelm a stream so that its shoreline shifts. A brushfire can also damage any and all natural features that you use to mark your property's boundaries! After such a disaster, even if it was very minor, have the land surveyed so that you can ensure you know the property's current boundaries, and are not relying on something that has moved out of place.
Before removing any items
You may know to have your property surveyed before you add a fence or other such item, to ensure you don't encroach on your neighbour's property. However, it can also be good to have this done before removing any item from your property, as that item may actually be on the other side of your property line! Removing an item that is actually on your neighbour's property could mean legal liabilities for you, as well as costs for repairing any damage to their property because of having a shed, tree, or other such item removed. To avoid these risks, have the property surveyed before this work begins.
If your bank is requiring flood insurance
If your home is located in a flood zone, you may be required to get insurance if it's below the flood elevation line for your area. While the bank may have the right to require this insurance, it can be good to have a survey done before you agree to this type of policy. It may be that your home is above the flood elevation, or outside the flood zone, so that this insurance is not legally required. Talk to a property lawyer about your rights in this case, but have the survey done as well, so you know how your property is affected by these boundaries and zones.