Knee walls are the short walls that support under sloped ceilings. It can be found in story-and-a-half homes and in rooms above the garage. Knee walls turn attics into living space, but they’re challenging to insulate. To quickly insulate rooms with knee walls, builders typically use fiberglass batts between the studs and fit blown insulation between the floor joists.
This doesn’t work very well because air from the vents can flow freely through unprotected batts. Knee walls don’t have sheathing around the back, so the batts can fall out of the stud bays. Next thing you know, you’ll be seeing the fiberglass batts on the floor.
This means that cold air can now enter your home through cracks around the access doors, holes in the walls, or through unsealed electrical boxes.
If your knee walls also share space with a conditioned room in your home, a good option is to combine traditional insulation and foil radiant barrier insulation.
Your goal is to wrap the outside of the room with the radiant barrier. Then, when the wall is exposed to the attic, the radiant barrier is facing the attic air space.
This method requires paying special attention to the air gap. If it’s compromised, then the foil won’t work effectively as a radiant barrier. By using spacers, you can make sure the air gap won’t collapse and close itself off.
One of the best approaches to creating an energy-efficient knee wall is to make sure it’s airtight and insulated well. The foil isn’t what causes moisture — it’s the leaking air. When it’s tightly sealed, warm air won’t leak out of the room, thus preventing moisture problems and helping you save on energy bills.
Another thing to consider is the knee wall room sharing a roof line with the roof of your home. There’s a chance that the heat gain in the room is going to come from the ceiling. To fight the heat gain, install radiant barrier foil on the roofline of the room, too.
With Air Solutions Heating, Cooling, Plumbing & Electric, we'll make sure that your knee walls are insulated and energy-efficient, saving you loads of money in the long run. Call us at (918) 241-2362 today. Together, we can formulate a game plan to seal your knee walls once and for all. You can also leave a message on our contact page. Other services we offer include indoor air quality and ventilation, heating furnace repairs, home energy audits, or heating installations, and more!