News and Events: Our Blog

Why Is The Room Over My Garage So Cold?

Monday, October 28th, 2013 by Brian Stewart

rigid foam board installation helps this St. Louis home keep warm.Does your home have a room above a garage?  Does that room tend to be cold during the winter?  If so, you are not alone.  This is one of the most commonly encountered winter problems in the St. Louis area.

The cold room may be the result of several things.  Most often, the problem comes from below.  The large cavity between the floor and the garage ceiling is often filled with cold air.  The cavity is usually 12 or more inches in height and cold outside air flows in through the band joist to fill the cavity.

When your home was constructed, the builder probably installed fiberglass rolls of insulation in the cavity under the floor.  That insulation is usually ineffective because the continuous flow of cold air goes through and around the insulation and comes directly in contact with the bottom of the floor.

To make matters worse, over time gravity pulls the fiberglass insulation away from the underside of the floor increasing its exposure to cold air.   The result is a very cold floor.  So cold, it often makes the entire room feel cold.

What can I do about my cold floor?

How do we fix it?  The best way is to “dense-pack” the cavity between the cold floor and the garage ceiling.  The dense-packing process fills the cavity with cellulose insulation and packs it under sufficient pressure that it cannot settle over time.  This keeps the insulation in full contact with the underside of the floor and stops air from moving inside the cavity.

If the insulation were simply blown into the cavity without enough pressure, it would settle.  The settling would render all the insulation useless because it would leave a layer of cold air directly beneath the floor above.

Sometimes a room above a garage is referred to as a bonus room.  In this case, the room is often constructed inside what would otherwise be an attic.  In this situation, the wall insulation can often be a problem in addition to the cold floors.

What if it's the walls?

The walls are usually finished with drywall and fiberglass insulation batts are often placed next to the drywall.  This leaves the insulation exposed to the cold air in the attic.  Insulation batts used in this fashion are ineffective because, like the floor, cold air flows around and through them.  Cold attic air is directly in contact with the walls.

The fix for this is to cover the insulation with an air barrier to stop the airflow.  We usually use spray foam or rigid foam board for this purpose.  Remember, spray foam air seals and insulates at once! With the air barrier in place, the insulation can do its job.  The result?  A warm and toasty room over the garage. Contact us today to schedule a home energy audit or an estimate for our other services!

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About the author
Brian Stewart is the General Manager of Dr. Energy Saver St. Louis. He has many years of experience making homes more comfortable and energy efficient.

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