Finishing the basement can seem like a very appealing way to expand your home's livable square footage without a major renovation.
Unfortunately, many basements can be cold and unappealing, even after you finish them.
That discourages both family and guests from actually using the basement space.
Why are basements so cold? The chilly air in your basement comes from a number of different factors.
Ground Temperature The temperature under the surface of the earth doesn't fluctuate as much as the temperature above.
That's because it's not exposed to the daily changes caused by the sun, and it has a high thermal mass, or ability to store heat.
Just two feet below the surface of the ground, the temperature fluctuates by only about 1 degree Fahrenheit over the course of 24 hours.
In many caves and caverns, the temperature is in the mid-50s all year round.
The ground transmits this relatively low, stable temperature to your basement, making it feel chillier.
Slow Heat Adjustment The thermal mass of the ground and its slow reaction to changes on the surface cause basement temperatures to adjust very slowly.
In some cases, the lag can almost be a full season behind the outside weather.
This is the reason that basements seem even colder than usual during the spring and early summer, but aren't as unwelcoming during the early fall season.
Solar Heat Gain Your basement temperature may also be indirectly affected by the solar heat gain that occurs in the upper floors of your home.
If you have a heating system where both the basement and upstairs areas are supplied by a single furnace, you could suffer from this problem.
Because the heat of the sun warms your home's upper floors but not the basement, the furnace shuts off before the basement warms up.
This problem is reduced in walk-out basements, which have more windows and greater heat gain.
Heat Rises What heat your furnace does produce raises quickly through your home, especially if the basement has free ventilation to the rest of the house.
That's why your basement may feel chilly even if you use supplemental heat sources like electric heaters.
You can combat this problem somewhat by using fans to recirculate the air back downstairs.
High Humidity Basements are humid places, due in part to the moisture that rises from the earth and up through an unsealed concrete slab.
Since older homes don't have a vapor barrier below the slab, the humidity can be as high as 60 percent - the point where mold begins to grow.
Even when basement humidity is lower, your downstairs areas may seem cold and clammy.
That's because the extra water allows your body to shed heat more quickly, using much the same mechanism as sweat on a hot day.
Add a dehumidifier to dry your basement air and improve the apparent temperature.
Heat Register Imbalance This problem occurs mostly in single-zone heating systems when the homeowner opens and closes all the registers equally.
Since each room has its own heating needs, this technique pushes warm air into relatively warm spaces.
Consider closing your registers in south or west-facing rooms with plenty of windows.
If the registers have a good seal, they'll keep the heat in the colder areas of your home instead of making the sunny rooms feel stuffy.
Motorized registers can even perform this job on a schedule for maximum efficiency.
Unfortunately, many basements can be cold and unappealing, even after you finish them.
That discourages both family and guests from actually using the basement space.
Why are basements so cold? The chilly air in your basement comes from a number of different factors.
Ground Temperature The temperature under the surface of the earth doesn't fluctuate as much as the temperature above.
That's because it's not exposed to the daily changes caused by the sun, and it has a high thermal mass, or ability to store heat.
Just two feet below the surface of the ground, the temperature fluctuates by only about 1 degree Fahrenheit over the course of 24 hours.
In many caves and caverns, the temperature is in the mid-50s all year round.
The ground transmits this relatively low, stable temperature to your basement, making it feel chillier.
Slow Heat Adjustment The thermal mass of the ground and its slow reaction to changes on the surface cause basement temperatures to adjust very slowly.
In some cases, the lag can almost be a full season behind the outside weather.
This is the reason that basements seem even colder than usual during the spring and early summer, but aren't as unwelcoming during the early fall season.
Solar Heat Gain Your basement temperature may also be indirectly affected by the solar heat gain that occurs in the upper floors of your home.
If you have a heating system where both the basement and upstairs areas are supplied by a single furnace, you could suffer from this problem.
Because the heat of the sun warms your home's upper floors but not the basement, the furnace shuts off before the basement warms up.
This problem is reduced in walk-out basements, which have more windows and greater heat gain.
Heat Rises What heat your furnace does produce raises quickly through your home, especially if the basement has free ventilation to the rest of the house.
That's why your basement may feel chilly even if you use supplemental heat sources like electric heaters.
You can combat this problem somewhat by using fans to recirculate the air back downstairs.
High Humidity Basements are humid places, due in part to the moisture that rises from the earth and up through an unsealed concrete slab.
Since older homes don't have a vapor barrier below the slab, the humidity can be as high as 60 percent - the point where mold begins to grow.
Even when basement humidity is lower, your downstairs areas may seem cold and clammy.
That's because the extra water allows your body to shed heat more quickly, using much the same mechanism as sweat on a hot day.
Add a dehumidifier to dry your basement air and improve the apparent temperature.
Heat Register Imbalance This problem occurs mostly in single-zone heating systems when the homeowner opens and closes all the registers equally.
Since each room has its own heating needs, this technique pushes warm air into relatively warm spaces.
Consider closing your registers in south or west-facing rooms with plenty of windows.
If the registers have a good seal, they'll keep the heat in the colder areas of your home instead of making the sunny rooms feel stuffy.
Motorized registers can even perform this job on a schedule for maximum efficiency.