Why is one room in my house always colder than the others?
Usually, that room has more exterior wall, sits over a garage or crawl space, or was added later with less insulation. Empty wall cavities and air leaks let heat escape faster than your system can replace it. Insulating the walls and ceiling and sealing the gaps is the lasting fix, not closing vents in other rooms.
Almost every Central Kentucky house seems to have one. The back bedroom where nobody wants to sleep in January. The bonus room that needs a space heater. The sunroom addition that is lovely in October and useless in February. The rest of the house is fine, and that one room never catches up.
It is easy to blame the furnace, but if the other rooms are comfortable, the furnace is probably doing its job. The problem is almost always the room itself: how it was built, where it sits and what is in its walls and ceiling.
What makes one room lose heat faster than the others?
Heat leaves a room through every surface that touches the outside or an unheated space. The more of those surfaces a room has, and the less insulation they hold, the faster it cools.
A room in the middle of the house might share only one wall with the outdoors. A corner bedroom shares two. A room over a garage loses heat through its floor as well as its walls. An addition with a low roof may have a thin ceiling and walls built to a different standard than the main house.
Then there are air leaks. Cold air slipping in around a window frame, an outlet or the rim of the floor framing makes a room feel colder than the thermometer says. So does sitting near a cold wall, because your body loses heat to the surface beside you.
Which rooms in Lexington homes tend to run cold?
Some rooms come up again and again in Central Kentucky homes.
Corner bedrooms. With two or three outside walls, they have more surface losing heat. In homes built before the 1970s, those walls are often empty.
Rooms over a garage. Bonus rooms in newer homes and bedrooms over attached garages in older ones lose heat through the floor into a space that is barely warmer than outdoors. The attic spaces on either side of a bonus room are a common weak spot too.
Additions and enclosed porches. These were often built years after the main house, sometimes by a different builder, and the insulation does not always match. Low-slope roofs over additions can leave very little room for attic insulation.
Upstairs rooms in story-and-a-half homes. Lexington has many of these. The sloped ceilings and short knee walls upstairs are often poorly insulated, so those rooms run cold in winter and hot in summer.
Rooms over a crawl space. Floors above an open or poorly sealed crawl space feel cold underfoot, which makes the whole room feel chilly even when the air is warm.
How can you figure out what is wrong with your cold room?
You can learn a lot in 15 minutes on a cold evening.
Start with the walls. Lay a hand flat on the inside of each exterior wall in the cold room, then on an interior wall. A clear difference often means the exterior wall has little or nothing in it.
Check the outlets and switch plates on outside walls. If you feel a draft, air is moving freely through the wall cavity.
Look up. If the room has an attic above it, check the insulation depth over that room specifically. It is common to find a decent layer over most of the attic and a thin or disturbed patch over one room, often where a light was installed or a cable was run.
Look down. If the room sits over a garage or crawl space, feel the floor. A noticeably cold floor points to the space below.
Finally, check the supply vent. If very little air comes out compared with other rooms, there may be a duct problem. That is a job for a licensed HVAC technician, and it is worth ruling out before you spend money on anything else.
What actually fixes a cold room?
It depends on what you find, but the fixes fall into three groups.
Fill the walls. If the exterior walls are empty, injection foam can fill them from the outside through small holes that are plugged and patched afterward. Your drywall or plaster stays in place. In a corner room with two empty outside walls, this is often the single biggest change.
Top up the ceiling. If the attic above the room is thin, blown-in insulation brings it up to the recommended level. Lexington is in climate zone 4A, where ENERGY STAR recommends R-60 for an uninsulated attic and R-49 when adding to 3 to 4 inches.
Seal the leaks. Gaps around the attic hatch, recessed lights, plumbing, wiring and the rim joist all let cold air in. Sealing them is usually done before adding insulation, because the openings are easier to reach.
Most cold rooms need more than one of these. That is why it helps to look at the room as part of the whole house rather than treating one symptom.
Myth vs. fact: cold room edition
Myth: Closing vents in the warm rooms will push more heat to the cold one. Fact: Closing vents can throw the system out of balance and often does little for the cold room. The heat still escapes through the room's walls and ceiling as fast as it arrives.
Myth: A space heater is a fine long-term fix. Fact: A space heater warms the air for a while, but the walls and floor stay cold, and you pay to heat a room that keeps losing it. Fixing the room's insulation and air leaks deals with the cause.
Myth: New windows will solve it. Fact: Windows can help, but in a room with empty walls and a thin ceiling, the walls and ceiling usually cover far more surface. Check those first.
Myth: If the rest of the house is warm, the insulation must be fine. Fact: Insulation is often uneven. One room can have empty walls or a disturbed patch of attic insulation while the rest of the house is in good shape.
Myth: You have to tear out drywall to insulate an existing wall. Fact: Injection foam goes in from outside the house through small holes that are patched afterward, so your interior walls stay as they are.
Does the rest of the house matter if only one room is cold?
Often, yes. A cold room is sometimes the most obvious sign of a problem that runs through the whole house. If one corner bedroom has empty walls, the other exterior walls may be empty too, and the rest of the house is simply warmer because it has fewer outside surfaces.
ENERGY STAR estimates that air sealing and adding insulation in attics, floors over crawl spaces and basement rim joists saves homeowners an average of 15 percent on heating and cooling costs. Results vary by house, but fixing the cause usually helps more than one room.
Can you fix a cold room in the middle of winter?
Yes. Injection foam and blown-in attic insulation can both be installed in cold weather. There is no reason to spend another January avoiding that room or running a space heater while you wait for spring.
Find out what is behind your cold room
You do not have to guess. Request a free inspection from USA Insulation Central Kentucky, and we will check the walls, ceiling and air leaks in that room, explain what we find and give you a written estimate for your Lexington-area home.
