Attic insulation in your home can get pretty nasty. Over many years it sits there collecting dirt, dust, pollen, bugs, rodent feces, and more. This was the case for a Leesburg, VA homeowner. As well as having old insulation, this customer had ductwork running through her attic. This is the worst possible place to locate ducts. Attics are the extreme opposite temperature of the air your ducts are trying to distribute to your rooms. Also, since attics are vented we should think of them thermally as outside in the winter. We need to keep an absolute boundary between our living space and the attic air so that heat doesn't pass up through our ceilings in the winter (conduction).
Solution
We took several steps to provide a solution to this homeowner. We removed and properly disposed of all of the old and yucky existing insulation in the attic, and then air-sealed all accessible penetrations and top plates with expanding polyurethane foam. We installed TiteShell Recessed Light Fixture Covers over the top of can lights and sealed them with our spray foam to prevent air leakage as well. Next, we encapsulated the duct system in the attic with 1 inch of closed-cell spray foam. This keeps the air running through the ductwork at the correct temperature. Then we installed a Rockwool Chimney Wrap to insulate the metal chimney and we also installed Rockwool batt insulation in the ceilings that sloped over the family room. Finally, we blew in TruSoft cellulose insulation to insulate the attic floor. Now this homeowner stays nice and warm all winter long in her home. Plus, her home stays cooler and more comfortable in the summertime too!
A Comfenergy production crew member starts to remove all yucky, old insulation from the attic.
Air moving through a vented attic deposits dirt and dust into fiberglass batts. This is called wind-washing. Dirty fiberglass batts have a significantly reduced R-value.
Ducts are typically very poorly insulated with fiberglass insulation and air passes right through them. In winter, the attic cools the duct and the air in it. So instead of having 120-degree air that you paid to heat coming out of your registers into your rooms, it may only be 90 degrees- making you uncomfortable and the furnace run longer to heat your home.
Once the old insulation is removed and the attic is clean, the air sealing begins. It's important to carefully air seal the many various points where air from your home leaks up into the attic and is lost. We use polyurethane expanding foam to air seal, called ZYP Foam.
To prevent leaks from the metal chimney flue, we wrapped it with Rockwool fire-resistant insulation. Rockwool is composed primarily of basalt rock and a recycled steel-making byproduct known as slag.
We used Tight N' True Boot Encapsulation for the ductwork. We sealed and insulated register boots or mixing boxes with polyurethane spray foam.
OSB Damming was installed to reduce the possibility of insulation from falling onto the HVAC system, catwalk, or storage decking.
TruSoft Cellulose insulation is blown into the attic. Although cellulose is made of paper, thorough mineral treatment provides it with permanent fire resistance. Cellulose also does not support mold growth, and the borate minerals that it is treated with, prevent insects and rodents from eating it or making homes in it.
Attic hatch pull downstairs are necessary to access the attic, however, when closed they can leak a LOT of air. We installed an Attic Zippered Tent to address this problem.
