Heating & Cooling Services

Attic & Air Sealing

It’s that time of year when people begin to notice cold spots and drafts in the home. While the air leaks around windows and doors are significant and most noticeable, you are probably losing a lot more air and energy in your attic and basement. In many homes, the combined air leaks in these two areas add up to a half-window being open all day long.

Think of all the money you are spending to heat and cool your home. If someone left a window or door open, you would be pretty upset, right? Well, that is effectively what is happening in your attic and basement. There are many little holes around doors, windows, soffits, and where utilities enter the home. Combine this with inadequate insulation, and are wasting hundreds of dollars’ worth of energy every year and creating an uncomfortable home for you and your family.


Find Air Leaks

The most common air leaks in a home are found in and around the following areas:


How to Seal Air Leaks

You can seal most air leaks with a combination of caulk, weatherstripping, expandable foam spray, and mastic sealant.


When You Should Hire a Professional

Call a professional as soon as possible if you notice any of the following signs while searching your home for air leaks:

  1. Wet insulation, a sign of leaking roof or HVAC system
  2. Mold and mildew, a sign of a moisture and health problem
  3. Condensation near HVAC system, a sign of a potential ventilation and / or carbon monoxide problem
  4. Ice dams on the eaves of your roof, a sign of an attic ventilation and insulation problem
  5. Knob and tube wiring, a potential fire hazard
  6. Damaged wiring, a potential fire hazard

Sealing around light fixtures and other electrical devices can create a fire hazard. Call a professional to help you add insulation around recessed lighting and attics.

There are some potential electrical and fire hazards that could put you at severe risk of injury if you are not completely confident in your abilities. Extra care must be taken whenever insulation around HVAC, plumbing, and electrical equipment. 

Sealing Attic Air Leaks

Seal and Insulate with ENERGY STAR.

Furnace, water heater, and chimney flues (metal/masonry) should be sealed with aluminum flashing and heat-resistant caulk. Plumbing pipes made of cast iron or PVC should be insulated with expanding foam or caulk depending on the size of the gap.

WARNING: Flues get very hot. Use extreme caution when working around furnace, chimney, or water heater flues.

It’s a good idea to create a metal dam around your flue to prevent any insulation from getting too close to the pipe. Cut a piece of aluminum flashing to create a metal barrier. If your flue is round, cut a half-circle into two pieces of aluminum flashing (have them overlap by about 3 inches) and nail or staple them into place.

Once you have the base down, seal the gap around the two pieces of aluminum flashing and the metal flue with heat-resistance caulk (do NOT use expandable spray foam).

To prevent any insulation from getting too close to the flue, cut another piece of aluminum and cut slots around 1-2 inches at the top and bottom. Bend out the tabs at the top and bottom and wrap the aluminum around the flue. Secure it by nailing or stapling the bottom tabs to the wood or drywall. Now, you can put insulation around the metal dam without fear.

If you do seal air leaks around flues, make sure that you use heat-resistant caulk.


Foam or Caulk Small Gaps in Your Attic

While most of the air leaks in your attic are probably covered up by insulation, you can detect these air leaks by looking for patches of dirty or dark insulation. The dirt comes from dusty air leaking into your attic.

You might also notice some patches of ice or frost. This is a result of moist air leaking into your attic and then freezing when it hits your cold attic.

Once you seal the air leak with caulk or expandable foam, it’s not necessary to replace the insulation. Just put it back into place.

Seal small gaps with caulk (up to ¼ inch) and expandable foam spray (up to 3 inches). Wear gloves and clothes you don’t care about. Once released, the caulk or foam is very difficult to remove.

Caulk around plumbing and wiring holes. If gaps around plumbing pipes and vents is larger than 3 inches, you can use some fiberglass insulation to supplement the effort.

Fill small holes with caulk or expandable foam spray. If there are any gaps that are larger than 3 inches, you can stuff some fiberglass insulation into the gap and then fill up the remaining space with expandable foam.

Attic Hatch Insulation

Once you have finished sealing all of the leaks in your attic, the next step is to weatherstrip your attic hatch or door.

If you don’t already have wooden boards surrounding the perimeter of the opening, you can cut some 1×3 boards and nail them into place with 6d nails. Apply your weatherstripping to the top of the new wood stops.

After weatherstipping the hatch or door, cut a piece of rigid foam board insulation the size of the door and fit it into place on the back. You can also purchase pre-made insulated attic stair covers from your local home improvement store.

Use hook-and-eye fasteners to close the attic door. Make sure the weatherstripping is compressed when the door is closed and hooks are latched.


Air Duct Sealing

While you are in the attic sealing air leaks, look for any ductwork that may be up there. If you have ducts that aren’t sealed, you are probably leaking a lot of conditioned air into your attic space. Sealing duct leaks can improve the efficiency of your HVAC system by around 20%.

When the furnace or air conditioner is on, check for air leaks around the duct connections with your hand, a lit incense stick, or a thing piece of toilet paper. Use mastic sealant or aluminum foil tape (not duct tape) to seal all of the duct connections. Mastic sealant paste is a slightly more effective and durable than HVAC foil tape.

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