n many parts of the country you'll find basements in every home. Why are they so common in some areas and not in others?
The reason might surprise you.
THE FROST LINE
Basements are most common in cold climates where the frost line—the depth to which the ground freezes in the coldest of weather—is deep.
Buildings have "footings" that anchor the structure to the ground. To avoid damage from the freeze/thaw cycle (which could compromise the structural integrity of the building) footings must extend below the frost line.
In cold climates the frost line can be many feet deep so when building there, you can either dig deep trenches for footings, or you can spend a little extra money to also excavate for a basement. The minimal extra cost of excavation and another subfloor is worth it since you are paying to dig the deep footings anyway and you get a basement out of the deal.
BASEMENT PROS + CONS
Many people who have lived with basements wonder how they could ever live without one. Basements provide storage and room for mechanicals. Some are finished and used as extra living space. While they make economic sense in cold climates that require deep footings, they have their pros and cons.
PROS
Safe Rooms
If you are building in "tornado country" you might opt for a basement even if your climate doesn't require deep footings. Safe rooms, built to withstand tornadoes, are more protected if they are built underground.
Personal Preference
In the heat of summer, spending time (or sleeping) in a cool, dark basement might be your first choice. If it is, nothing can replace a cool, dark basement!
Wine and Root Cellars
If you need space that stays consistantly cool for food, wine or other specialty storage, a basement might be your best option.
A Smaller Footprint
On small lots, eliminating a basement and adding storage space at ground level can cut into your yard space. (In this case, using a storage/attic truss system above the garage can give you garage/attic storage space without impacting your yard.)
CONS
Lack of Natural Light
Unless you build on a slope and are able to have a walk-out basement (which also allows day lighting to enter from one side) the most natural light you can hope for is from window wells. Even walk-out basements feel "flat" because natural light only enters from one direction.
Humidity
In all but dry, desert climates, basements can be humid and a source for mold and mildew. Dehumidifiers and moisture barriers can help, but you're fighting nature and keeping your basement dry can be an ongoing battle.
Accessibility
In most cases, basements are accessed by stairs. This can pose a problem when transporting large items or for people with mobility issues.
Extra Costs for Rocky Soil
In some areas, rocky soil can add considerably to excavation costs. Sometimes even blasting is necessary to clear rocks for a basement. A soils test (and your neighbors) can let you know if this might be an issue.
A SMART OPTION FOR MILD CLIMATES
In warmer climates, footings are only a couple feet deep. When deep footings and safe rooms are unnecessary, it's often preferable to build "basement" space at ground level—if you have the room—since, with basements, the additional costs of excavation and retaining walls, moisture control, stairs and an extra subfloor add up, and you end up with a dark, sometimes humid and not particularly inviting space. Putting the space on the ground level is more comfortable because windows and doors bring in natural light along with easy access to the outside and the rest of your home. And, since deep footings aren't needed, the cost can be comparable or even less than building a basement!
