unfinished attic

How To Insulate An Attic Yourself And What Materials To Use

Andrew Dehan7-Minute Read
December 30, 2020

Physics teaches us heat rises. In the winter, you can see the puffs of steam or smoke coming from your chimney as the heat exhausts upward. If your home has a hard time staying warm, your heat could be escaping through your attic.

Having a well-insulated attic will help keep your house warm in the winter and cool in the summer. Read on to learn how to insulate an attic yourself.

Preparing For A DIY Attic Insulation

With any big project, it’s important to do your prep work before diving in. Before adding insulation to your attic to prepare your home for winter or a hot summer, follow these steps:

1. Choose The Best Insulation Type For Your Attic

Insulation comes in two main forms: batts/rolls and loose fill.

  • Batts and rolls: Also called blanket insulation and meant to fit between your attic’s joists and wall studs. Most batts or rolls are made of rock wool and/or fiberglass. Installation is simple, but it may not insulate as well as loose fill.
  • Loose fill: Known also as blown-in insulation and designed for tighter attic spaces. A blower machine is required to install this type of insulation. Loose fill insulation doesn’t take very long to install but can generate a lot of dust and requires a little more know-how.

These can be used on their own or in combination. Many people will lay down batts in between the joists and wall studs, then cover it with loose fill for ample protection.

2. Pick Your Insulation Materials

There are a few different materials to choose from:

  • Fiberglass: The most common and affordable insulation material. Fiberglass is made to slow airflow through its material, and newer versions have done away with the common skin and lung irritants. The downside of using fiberglass batts is they don’t insulate as well other forms of insulation. They may not be appropriate for insulating an attic.
  • Cellulose: Made from recycled paper and other materials and treated to be fire-resistant. Cellulose creates a lot of dust, so most pros use a wet-spray cellulose, adding a small amount of water to control the dust. It’s environmentally friendly and relatively cheap.
  • Rock wool: Also called mineral wool or slag wool, rock wool is the more expensive material available. It is made from Basalt rock and recycled steel slag. It’s known to be fire-resistant and can act as a mold repellent. 
  • Spray foam: Spray foam is incredibly efficient but is also expensive. It’s not a DIY option. If you want the zero maintenance and enhanced thermal protection, you’ll need to hire a professional.

3. Determine The Appropriate R-Value

An R-value is a measurement of insulation. Technically, the R stands for resistance to heat flow. It’s a measurement of how much an object traps heat. The higher the R-value The U.S. is broken down into seven different zones depending on the climate.

Zone 7 includes most of Alaska, the northernmost parts of the continental U.S. and areas in Wyoming and Colorado with high elevation. On the opposite end, zone 1 is the warmest regions, including southern Florida, Hawaii and Puerto Rico.

Since heat rises and leaves through your roof, homes in cooler regions require more insulation to keep heat in.

Here are the recommended R-values for attic space by zone.

  • Zones 6 and 7 – R49-R60
  • Zones 4 and 5 – R38-R60
  • Zone 3 – R30-R60
  • Zones 1 and 2 – R30-R49

Research what zone you’re in to find out the minimum R-value you will need.

4. Figure Out How Much You Need

How much insulation you need depends on four factors:

1. The size of your attic

2. The R-value you’re insulating to

3. The material you’re using

4. Whether the material is loose fill or batting

The type of insulation and its R-value will determine its depth on the attic floor and the thickness applied to the roof. You’ll need to measure your attic’s dimensions and do the math to determine exactly how much is needed.

5. Remove Old Insulation

Pull out the old insulation. Be very careful. Make sure to wear gloves and a mask for protection. Batting and blankets can be removed by hand with a few tools. Loose fill cellulose will need to be sucked out by a 1,500 HP-plus bucket vacuum. Store removed insulation in large trash bags.

At this point, you’ll need to fix mold problems if you discover them. If the mold is extensive, or you discover something else insidious, like asbestos, stop what you’re doing and hire a professional.

6. Wrap Your Pipes

In cold weather, water pipes can freeze and in hot weather, they drip with condensation. To prevent this, wrap your pipes. Copper pipes can be wrapped in foam sleeves, where plastic pipes should only be wrapped with automatic heat tape. Measure your pipes’ dimensions, as well as counting valves and faucets, to determine how much insulation you’ll need.

7. Seal Any Air Leaks

Inspect your attic for air leaks. These typically occur in gaps around windows and your chimney flue. For small gaps, you can use a sealing caulk. For larger gaps, you may want to use an expanding foam spray to properly prevent heat loss.

8. Box The Lights

Insulation can be flammable so it’s important to be careful when insulating around light fixtures. The only type of lights that can come into direct contact with insulation are insulation contact lights, or IC-rated lights. Lights should be covered with a properly rated cover, keeping the insulation away from the heat and electricity.

9. Preserve The Airflow

You need to block off areas to keep the insulation away from the underside of the attic’s roof, especially if you plan to use blow-in insulation. If you block this off, you will block off airflow, which could encourage things like mold growth.

10. Address Any Other Concerns

Before you proceed to putting in insulation, you should address any other concerns. Repair water damage and remove any mold. If you want to install built-in storage decks, now is the time to do it.

11. Be Safe

Working with insulation can be hazardous. Fiberglass contains small pieces of glass that are terrible for your lungs and skin. Likewise, cellulose can create a lot of dust you shouldn’t be inhaling. Take these precautions to make sure you don’t hurt yourself:

  • Wear the proper equipment and clothing (dust mask, goggles, gloves, long pants and sleeves). 
  • Avoid standing directly on the joists or you’ll risk falling through the attic floor. It is recommended to stand on a piece of plywood set across the joists so your weight is distributed.
  • Use portable lanterns or workshop lights for visibility while working in the attic.

How To Add Insulation To Your Attic

How you install insulation depends on the type of insulation you’re working with. Follow these suggestions to have a successful install.

Batt And Roll Insulation

Batt and roll-style insulation is simple to install. Carry up to the attic unrolled and roll it out, starting in the corner furthest away from the hatch. For insulating your attic, make sure to use unfaced batts.

Tuck the insulation into the gaps between the joists and studs. Cut the insulation to fit and cut holes in the insulation for any wiring. You want to pull this wiring up so it sits on the insulation, instead of being trapped by the insulation.

To quickly cut batts or rolls, use a utility knife that has a long extension and snap-off blades. Extend the knife all the way out so it can cut through the thick insulation. Use a board like a two-by-four to apply pressure, compacting the insulation and creating an edge for you to cut along.

Check the depth the insulation to determine if you need to add more. If you need to add another layer, lay it perpendicular to the first layer. This will help prevent any leaks.

Loose Fill Insulation

For blown-in loose fill insulation, you will need to rent a blowing machine. You can do this for a reasonable price at most home improvement stores. Before blowing in the insulation, block off any vents where you don’t want insulation going.

Read the instructions that came with your rented machine and set it up correctly. Blow in the insulation, starting away from the hatch. After a few minutes adding insulation to a specific area, stop to check the depth. You want to keep the depth relatively even.

How Much Does It Cost To Insulate An Attic?

There are several variables when calculating how much it will cost to insulate your attic.

  • Type of material and insulation you’re using.
  • Square footage of your attic space.
  • Additional materials and equipment.
  • R-value needed for your area

Large attics will need more insulation, as will homes in colder areas.

If you’re looking for a rough estimate, measure the square footage of your attic. Insulation cost varies between $0.65 – $1.50 per square foot, depending on the type of insulation. Batts and rolls are typically cheaper than loose fill or blown-in insulation but may take you much longer to install.

That’s the cost of the insulation material alone. With blown-in insulation, you’ll also need to factor in the equipment rental price. With batts and rolls, you’ll just need some utility knives.

Bottom Line

Insulating your attic doesn’t have to be intimidating. It’s a project, but with the right preparation, it’s a doable one. Having a well-insulated attic can save you big time on heating bills. Take the proper precautions and do it right, and you’ll have an insulation job that could last 10 or 15 years.

Want more helpful homeowner tips? Check out the Rocket Homes® Homeowner Guide.

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Andrew Dehan

Andrew Dehan is a professional writer who writes about real estate and homeownership. He is also a published poet, musician and nature-lover. He lives in metro Detroit with his wife, daughter and dogs.