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How to Insulate an Attic & Slash Your Heating and Cooling Bill

by | Mar 1, 2017 | Additions, New Construction, Remodels

Without proper insulation, a house won’t be able to maintain it’s temperature. So that cool air you pay for is wasted and your money literally goes out the window. If you are running into drafts and high heating bills, it is probably time you learn how to insulate your attic or add more to bulk up.

How Much Does it Cost to Insulate an Attic?

On average, hiring a contractor to install insulation onto the floor of your attic will cost $1,300. On the bright side, you can expect a whopping return on investment, because home buyers are willing to pay an average $1,400 extra for you home if the attic is insulated.

In other words, you get back all that money once you sell! if you want to save even more money, you can go the DIY route where you pay only for materials, which will cost around $580 for 500 square feet.


If your attic already has walls and floors, the process is more complicated and you will probably have to hire a pro to spray foam insulation underneath. However, if your attic is unfinished, the easiest way to add insulation is to lay it on the floor between the joists that make up the wood framework of your house.


How Much Attic Insulation Do You Need?

That depends on where you live. Colder areas require R-Values: the measure of the insulation’s ability to resist heat traveling through it. In cold climates, you will want a minimum of R-49; in hot climates, R-30.

If you are wondering about the recommended R-value for your region, take a look at Energy Star’s Guidelines by zone. Once you know the R-value, you just measure the length and width of your attic to determine how many square feet of insulation you should buy.

Protective Gear Needed

Insulation is not the best for your skin and can cause you to itch and you also don’t want to breathe in the tiny particles. So you will need:

  • Safety Glasses
  • Gardening or Working Gloves
  • Face Mask
  • Disposable Coverall Suit
  • Wooden Boards to walk on, versus balancing on the joists

Step 1: Seal Cracks First

Before you begin, you will want to make sure you have sealed any gaps or openings that are allowing heat or air conditioning to escape. Silicone caulk work well whit it comes to stopping air leaks around cutouts, such as electrical boxes. Metal flashing and high-temperature silicone caulk can be used when filling gaps around flues or chimneys.

Step 2: Pick Your Insulation

There are 2 main types of insulation, each with their own pros and cons depending on your attic.

Fiberglass Batts: This blanket-style or roll-on form of insulation is the simplest to work with. It is sold in 15 or 23-inch widths, they are designed to fit easily within most typical joists. if your home has some insulation but not enough, batts can be rolled out over existing insulation. When laying down you insulation, cut to size as necessary and be sure to start at the perimeter, then work your way toward the exit so you don’t insulate yourself into a corner.

Loose-fill Insulation: This insulation requires a machine that blows a stream of fiberglass or cellulose over the existing attic floor framing. It is typically installed by a contractor, but you can also rent a blower from a home repair store. One benefit it this insulation fills in tiny gaps and hard to reach places.

Step 3: Keep Soffits Clear

While insulation should extend all the way to the exterior wall, take care not to block the soffits. These are openings under the edges of your roof that help ventilate a home. To keep these openings clear, you can install baffles, which keep insulation from expanding into these areas.

Step 4: Watch Out Around Lights

If you are installing near recessed lights, you will want to use sheet metal or wire mesh to create a barrier around these fixtures. If insulation comes into contact with lights, it can cause a fire, unless the insulation is marked “insulation contact” or “IC” which means no barrier is needed.