How to Add Insulation in an Attic

A home with inadequate insulation is a home with unnecessary energy expenses, and it is a home that probably does not stay comfortable during the coldest months of winter and the hottest months of summer. A home that is inadequately insulated will not be as warm as it could be during winter months, and the heat source will have to operate more often to keep the home comfortable.

Likewise, a home with inadequate insulation will not stay as cool in the summer as it could, and the air conditioning system will run more often than it should. The roof and the walls will heat up during the warmest hours of the day, and, even after the sun has gone down, the walls will continue to radiate heat indoors. All of this can be easily remedied with insulation, though.

The Benefits of Adding a Blanket of Insulation

Vermiculite and cellulose insulation are easier to apply in awkward areas of the home, and many home improvement stores offer free use of an insulation blower with the purchase of loose insulation, but it is not always the best type to use.

Vermiculite or cellulose varieties must be applied at a greater depth than blanket varieties, and, since joists are usually six-inches deep, loosely applied insulation is not easy to contain on the attic floor. This also makes it more difficult to locate specific areas of the attic, which makes it more difficult to repair areas of the home that are only accessible that way.

For the do-it-yourselfer, blanket-style insulation is an excellent choice because it is easy to unroll and trim, it is not as messy as loose varieties, and it stays in place on the attic floor.

Choosing the Right Insulation for the Job

An attic that has never been insulated requires at least 6 inches of top-quality insulating material, and an attic with a thin layer of insulation can be insulated with 4-inch blanket insulation.

Blanket insulation typically comes in rolls that are twenty-four inches wide, since this is the most common width of open spaces between joists, but the R- rating varies. The R-rating determines how fast heat will pass through the material, and the higher the rating, the better the product.

Since various climates have different minimum building code requirements, contact your local building inspector to find out the minimum recommendation of insulating blanket material for your specific location, and choose a product with a higher R-value than recommended.

Although insulating blanket material with a higher R-rating will cost more initially, it will save money in the long run on heating and cooling bills. The insulation will eventually pay for itself, and the home will be more comfortable than ever.

Preliminary Safety Precautions

Before beginning, keep in mind that blanket glass fiber insulation can cause skin, lung, and eye irritation if handled without adequate safety gear. Cover exposed skin before beginning and wear protective goggles and a face mask to keep loose fibers out of the eyes and airways. In addition, wear rubber-coated gloves at all times when handling glass fiber blanket insulation to protect the hands and wrists from irritation.

Laying Rolls of Blanket Insulation

To add insulation to the attic floor, you will require enough blanket material to do the job, a heavy-duty shop vacuum, plastic sheeting for covering the blanket material that will insulate the attic opening, a heavy-duty staple gun, and utility scissors with long blades. You will also need a strong board to kneel on that will span the joists.

Before getting started, put on the necessary safety gear, and use a shop vacuum to remove any debris and accumulated dust. While kneeling on the board, unfurl the first roll of blanket insulation between the joists.

Make sure you have baffles in the eaves to allow for proper ventilation and then roll the insulation along the entire length of the first section of the attic floor while watching for electrical wiring. The wiring should be above the insulation to keep it from overheating.

When it becomes necessary to cut the blanket material to fit the length of the space along the attic floor, cut it using long-bladed utility scissors. Make sure the ends butt up against one another, and continue this process until the entire attic floor is covered with a blanket of insulating material.

Lastly, cut a section of blanket insulation to fit the attic opening or openings as well as sections of plastic sheeting to wrap around them. The plastic will help prevent insulation particles from getting into your eyes or on your skin when entering and exiting the attic. Staple the wrapped insulation into place with a heavy-duty staple gun to finish the job.


A blanket of insulation on the attic floor can make a huge difference in the comfort level of a home and in the amount of money spent on heating and cooling annually. It really is very easy to add insulation to an attic, and doing the job without professional help will save a great deal of money.

This is one do-it-yourself project that many homeowners cannot afford to put off, and the difference in the temperature level and how often heating and cooling units run will be noticeable almost immediately.