Yes, you should heat your basement. Finished or not it is important to keep the basement conditioned for:
- efficiency and
- health reasons.
Rising heat on the main floor will draw cold air from the basement and rim/band joist. This stack effect will draw cold air across the main floor resulting in cold feet and comfort problems.
Some of the coldest air in the home is in the basement and it will eventually end up being drawn up to higher levels.
Cold basement air will result in heat loss in potable water lines and basement ductwork. Since heat migrates to cold if the basement is colder than the air in the ducts a portion of that heat is going to migrate into the basement. If the ducts aren't sealed (cold air return side) you will actually drawn cold air out of the basement, causing a depressurization that draws more outdoor air into the basement through rim/band joist leaks.
This phenomenon also happens when people try to zone their homes when they only zone the supply side of the system. Cold air returns can depressurize a room by pulling the cold air out of the room which must be made up by pulling air from outside through thermal boundary bypasses.
In cold weather climates basements become an incubator for mold growth when the air is stagnant. Warm moist air condenses on cold foundation walls that reach dew point temperatures resulting in moisture and ultimately mold.
Basements without adequate air circulation smell musty - a sure sign of mold growth.
Weatherize before heating
Before introducing heat to your basement hire a contractor to weatherize the basement thermal envelop.
- Use foam sealant in rim/band joists, at top plates and any wood to concrete joints before installing adequate insulation.
- For below grade foundation walls insulate to a minimum of R-10.
- Do not use fibrous insulation since it can lead to mold growth when moisture passes through it to reach the cold foundation walls.