When you turn on the central heat in your home, you generally want the entire home to warm up. So when the top floor stays chilly, it can be pretty frustrating. This is usually only an issue in older homes. Here's a look at the common causes and what you can do about them.

Lack of insulation.

Many older homes were not initially well insulated. If none of the subsequent homeowners have improved upon the insulation, you might be losing all of your heat through the attic. (Hot air rises, after all.)

The Department of Energy recommends that most homes have 10 – 14 inches of insulation in the attic. If yours has less than this, you can purchase some fiberglass insulation at your local hardware store and unroll another layer on top of the existing insulation. If you check your insulation and find that it looks moldy or compacted, replacing it altogether will help keep your upstairs warmer.

Leaky Ducts

Today's air ducts are usually made in a pretty efficient, airtight manner. But this was not always true of ducts in the past. Older ducts may leak from the seams, meaning a lot of the warm air leaks out behind your walls before it even reaches your second story.

To see whether leaky ducts are likely to blame for your issue, hold your hand in front of an upstairs heat vent when the heat is on. Then, hold it against a downstairs heat vent. If there's a lot more air coming out of the downstairs heating vent than the upstairs one, leaky ducts are likely to blame. An HVAC company can seal your ducts to combat heat loss and keep your upstairs a lot warmer.

Poorly Arranged Ducts

In some older homes, the upstairs was not initially intended to be living space. So ducts may not have been run to the upstairs, or the ducts that did run up there may not have been intended to keep the space overly warm. Even if previous homeowners added more ducts since the original build, they still might not be getting enough heated air upstairs.

Re-working the ducts in a home with insufficient vents on the second floor can be a costly and involved project. Your HVAC technician can look over your home and give you an estimate, but you might be better off just using a few space heaters for supplemental heat upstairs.