Many Delaware homeowners have a bonus room over their garage that barely gets used. Why? It's either sweltering in July or freezing in January. That is not anyone's idea of a cozy living space.

The problem is that most garage ceilings (which serve as the bonus room floor) weren't insulated before drywall was installed. That means your extra room sits right on top of an uninsulated, often unheated garage space. In Delaware's climate of cold winters and hot, humid summers, that's a recipe for year-round discomfort.

Let's break down what's going on and how to fix it.

Bonus room over garage

Why Rooms Over Garages Are So Uncomfortable

Bonus rooms are trickier to keep comfortable than other parts of your house because they have more surfaces exposed to outdoor conditions. These surfaces include the floor below your bonus room, outside-facing walls, and seven a ceiling that borders your attic or roof. That's a lot of ways for heat to sneak in or leak out.

Construction Issues

Construction Issues

Most bonus rooms are built using attic-style roof trusses, which don't leave much room for proper insulation. This means the room's floor, walls, and ceiling may only have thin insulation, or none at all. Your bonus room needs dense, thick insulation to resist the heat and cold of our changing weather.

Air Leakage Problems

Air Leakage Problems

Even with some insulation, there are still challenges with drafts. Air sneaks in through gaps in the floor, wall joints, and around pipes or ducts. Attic knee walls and access panels often leak, resulting in a leaky thermal envelope. And you end up with a room that's drafty and uncomfortable.

HVAC Challenges

HVAC Challenges

The HVAC ductwork to these extra rooms is often an afterthought. Even if your bonus room has a vent, that doesn't mean it's getting enough air. Ducts running from your furnace or AC unit are often too long, too small, or poorly insulated. By the time air arrives, it's lost most of its heating or cooling power.

Strengthening Your Home's Envelope with Insulation

Focus on the Garage Ceiling (Bonus Room Floor)

The most important spot to insulate is the garage ceiling, aka your bonus room floor. Adding proper insulation creates a buffer that slows heat transfer.

  • In summer, insulation helps block heat from your hot garage rising into your spare room.
  • In winter, it helps keep warm air from escaping into your cold garage.

Remember, air sealing the floor boundary is just as important as insulation. Sealing drywall gaps, light fixture holes, and wire penetrations keeps air (and garage fumes) from drifting into your living space.

The “Drill and Fill” Insulation Solution

While it's best to properly address a garage ceiling's insulation during home construction, it can also be done retroactively. One of our installation techniques is "drill and fill" insulation. This is a smart retrofit method that adds dense-packed insulation without tearing apart the ceiling of your finished garage.

Here's how it works:

  • Our team members drill small access points in the garage ceiling below your bonus room.
  • Specialized equipment is used to densely pack loose-fill fiberglass or cellulose insulation into the cavity.
  • The insulation fills the entire cavity, even around wires and pipes.
  • The access points are carefully sealed and patched.

It's fast, clean, and doesn't require removing large sections of your ceiling.

Alternative for Unfinished Garages

If your garage ceiling is unfinished (with no drywall), you can simply install fiberglass batt insulation or spray foam between the joists, then cover it with drywall. The goal is to create a solid thermal barrier under your bonus room, regardless of which method you choose.

Don't Forget the Rest

While the garage ceiling is priority #1, don't ignore the exterior walls, attic hatches, or knee walls. Sealing and insulating these areas of your bonus room completes the envelope and maximizes comfort. You can even take it further by insulating your garage walls or upgrading the garage door to reduce temperature extremes.

The Benefits of an Insulated Bonus Room

Year-Round Comfort

Say goodbye to avoiding the bonus room in August or piling on blankets in January. You can finally use that spare room without sweating or freezing.  With proper insulation, it feels like any other living room in your house.

Energy Efficiency

A better-insulated home uses less energy. In fact, insulating and air sealing key areas of your home can save you an average of 15% on your heating and cooling costs. Your HVAC system won't have to work as hard, and your energy bills will thank you.

Better Indoor Air Quality

A sealed and insulated bonus room floor acts as a barrier to pollutants. It helps block garage fumes and moisture. This improves your home's indoor air quality and protects against mold and structural damage.

Noise Reduction

Insulation helps muffle garage noise, too. From door openers to car noise or buzzing tools, you'll enjoy a quieter atmosphere in your bonus room. It even softens the sound in the garage from footsteps in the bonus room above.

Versatility and Enjoyment

Fixing your insulation gives you the freedom to create a space you can enjoy all year long. Your properly insulated bonus room is the ideal spot for a:

  • Home office
  • Guest room
  • Craft room
  • Home gym
  • Home theater
  • Meditation room
  • Game room
  • Home library
  • Kid's media room

There's no shortage of bonus room ideas. It's all possible! Many Delaware families often need extra space, and this is a smart way to get it.

Enjoy Your Bonus Room Year-Round
with Delmarva Insulation

Stop letting your bonus room go to waste. With the right insulation and air sealing, you can turn it into one of the best spots in your house. It's not just about comfort, it's about value, usability, and efficiency.

Delmarva Insulation has been serving Delaware homeowners and builders since 2002. We specialize in new construction and retrofit insulation solutions that work, especially in our tough Mid-Atlantic climate.

Whether your bonus room needs a full upgrade or a simple insulation fix, our team is ready. We use high-quality materials, proven techniques, and local experience to get the job done right. Contact us today to reclaim your bonus room and unlock its full potential.

References

Delaware Climate Office. "Delaware's Climate." University of Delaware, n.d. https://climate.udel.edu/delawares-climate/. Accessed 24 July 2025.

Stone, Richard. "Energy Efficiency of Bonus Rooms." University of Minnesota Extension, reviewed 2018. https://extension.umn.edu/energy-efficiency/energy-efficiency-bonus-rooms.

Stone, Richard. "Framing and Air Sealing Homes in Cold Climates." University of Minnesota Extension, reviewed 2018. https://extension.umn.edu/energy-efficiency/framing-and-air-sealing-homes-cold-climates.

United States Environmental Protection Agency. "Methodology for Estimated Energy Savings." ENERGY STAR, n.d., https://www.energystar.gov/saveathome/seal_insulate/methodology. Accessed 24 July 2025.