Your Home and Insulation: You Probably Don’t Have Enough

The best way to lower the amount of energy needed to heat or cool your home is to keep your home’s temperature as even as possible and the best way to do that is to use insulation. Think of insulation as blanket that’s usually installed in your home’s walls, ceilings, and sometimes the floors. Insulation’s main job is to keep your home’s temperature from dramatic swings. Using the correct insulation (both type and amount) will save you money while making your home more comfortable.

  • In an existing home, it’s important to know the location and amount of insulation you already have, and then add insulation from there.
  • In a new home or a remodel, install as much insulation as you can, using the newest insulating materials available. Always talk to your builder since many  simply stick to what they’ve always used. Chances are good that you need much more.

Most old homes have far less insulation than new homes — an energy audit will help you find out where your home stands. If you don’t want to pay for an audit, your home’s original builder may still have records about the kind of insulation used in the construction process. If not, you can probably check your insulation yourself. Start in the attic and any spaces that adjoin unheated spaces, such as basements and garages, to see the types (and thicknesses) of insulation they have. To check your insulation:

  1. Use your circuit breaker to turn off the power to the room you’re checking.
  2. Locate an electrical socket on the wall.
  3. Remove the faceplate and use a flashlight to see into the space behind the wall.
  4. Determine the type of material there and use a ruler to measure its thickness.

Types of Insulation

There are many different types of insulation, including fiberglass, wool, plastic, spray foam, and natural materials. Knowing which one to use means understanding the level of insulation you’ll need and the R-value (ability of the insulating material to restrict the flow of heat) you’re looking to achieve.

Type of Insulation
Typical Materials
Method of Installation
Typical Uses
(batts or rolls)
  • Fiberglass
  • Rock wool
Fitted between studs, joints, and beams
  • Unfinished walls
  • Unfinished floors
  • Unfinished ceilings
Loose fill (blown-in or spray-applied)
  • Rock wool
  • Fiberglass
  • Cellulose
Blown into place or spray-applied using special equipment
  • Enclosed existing wall cavities or open new wall cavities
  • Unfinished attic floors and hard-to-reach places
Rigid insulation
  • Extruded polyesterene foam (XPS)
  • Expanded polyesterene foam (EPS or beadboard)
  • Polyurethane foam
  • Polyisocyanurate foam
For interior applications, must be covered with 1/2″ gypsum board or other building-code approved material for fire safety; for exterior applications, must be covered with weatherproof facing
  • Basement walls
  • Exterior walls under finishing (some foam boards include a foil facing that acts as a vapor retardant)
  • Unvented, low-slope roofs
Reflective systems
  • Foil-faced paper
  • Foil-faced polyethylene bubbles
  • Foil-faced plastic film
  • Foil-faced cardboard
Fitted between wood-frame studs, joists, and beams
  • Unfinished ceilings
  • Unfinished walls
  • Unfinished floors

After you’ve determined what kind of insulation you have, go to the Department of Energy’s online insulation calculator to learn how much insulation you might need for your specific region.

How to Seal Your Home

New homes are built to be much more tightly sealed than their older cousins. Older homes can develop gaps between framing members throughout years of settling. After insulating and sealing windows and doors, make sure you aren’t losing warm or cool air through holes and spaces in other parts of your home.

How to Seal Attics and Basements

To make sure your attic and basement are sealed properly, first conduct a detailed survey to find out where air leaks might be costing you money. Then, starting in the basement and using a very bright flashlight, follow the path of all plumbing pipes, HVAC tubes, chimneys, and, to a lesser extent, electric lines, starting at the point where they adjoin the furnace, septic or sewer pipe, or water heater. Do a visual inspection, following pipes and tubes through the walls and ceilings of your house, ending in the attic, where you typically lose the most heat. Look closely at electrical outlets, plumbing pipes coming from walls, fan exhausts for bathrooms, and recessed lighting for leaking holes. Seal up any cracks and holes with caulking foam.

If you can afford to add insulation to only one room in the house, make it the attic — attics are often insulation poor, especially under the roof decking.

How to Seal Attached Garages

If your garage is attached to your home, you may have noticed that the interior wall closest to the garage is cold in the winter and hot in the summer. Make sure whatever door connects your living space to an attached garage is weather-stripped and sealed tightly. Also consider insulating your garage, even if it’s just the wall that adjoins the house.

Take some time this weekend to check your homes insulation levels and remember: keeping things even (temperature wise) will lower the amount of money you spend on energy.

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