Installing Attic Insulation in Old Homes

A man preparing to install pink fiberglass insulation in a wall.
  • 5-6 hours
  • 600-800
What You'll Need
Utility knife
Tape measure
2 to 3 Sheets of plywood

Attic insulation is important, as not having it will raise your energy bills and cost you money. Many old homes lack the insulation they require. Luckily, adding insulation is simple and shouldn't take longer than a day.

Step 1 - Buy Insulation

There are a number of different types of insulation that are suitable for use in an older home. The most common of these, however, is rolled batt insulation, so that is the kind this guide will cover. Rolled batting insulation can be positioned in the attic space between the joists and also used to insulate cavities in walls between studs. Get the insulation with a vapor barrier on one side.

Step 2 - Measure the Attic

Measure the size of your attic in square feet by measuring both the width and height of the attic and multiplying them together.

If your joists are spaced 16 inches apart from one another, multiply the square footage of your attic by 0.90. If your joists are 24 inches apart, multiply by 0.94.

If you have an attic that is 1,000 square feet in size and the joists are 16 inches apart, you will need to purchase 900 square feet of insulation to fully insulate your attic space.

Step 3 - Prepare the Attic

It's important that you don't stand between the joists in your attic because, if you do, you could risk falling through the ceiling. Place sheets of plywood between the joists so that you have something to stand on that will prevent you from stepping through the ceiling and damaging it.

Step 4 - Install the Insulation

When laying the batts down, work from the far edge of the attic toward the center so that you have plenty of space to cut the insulation to the required size. Install the fiberglass insulation and position the plastic vapor barrier face down. This will prevent any problems caused by water damage.

The fiberglass insulation sheets need to be fitted close to one another so that the insulation has the best effect. The insulation can be positioned over the top plate of the walls, however you must be careful not to block the vents. Any small spaces can be filled using scraps of left-over insulation, which can be cut to the right size and fitted where needed.