Attic Insulation 4 - Preparation

An empty attic awaiting insulation.
  • 10-40 hours
  • Beginner
  • 1,000-2,000
What You'll Need
Dust mask
Hole saw
Extension cord
Spackling knife
Circular saw
Steel tape measure
Utility knife
Caulking gun
Staple gun
Blowing machine
2x4 boards
Tar paper
16 penny nails
Sheet metal flashing
Flexi-vent material
Drain pipe
Duct tape
Fiberglass insulation
Vapor barrier (6 mi. visquine)
Waterproofing sealant
Long, straight board
Closable vents
Rigid foam panels
2x2 furring strips
Sump pump
Soffit ventilation plugs
Shim material
Sheet metal, louvered, and screened vent
Continuous ridge vent
2-inch extruded foam panels
Wind turbine
Construction adhesive (for exterior use and foam panels)

So you learned in part three how to stay safe when doing your DIY attic insulation installation. Now, it's time to get everything you need to do the job right or you may risk compromising the efficiency of your insulation down the line.


Allow yourself three to four hours per 100 square feet when installing fiberglass batts or a vapor barrier in the attic. Allow yourself four to six hours per 100 square feet when installing furring, insulation, or a vapor barrier in the basement. Never try to rush an insulation job or the shoddy work will cost you down the line.

Permits and Codes

Codes for insulation requirements will vary in different parts of the country. A permit may be required in some areas if the work being done exceeds $100 in cost, so check with your local building inspector. Codes also will indicate required R-factors of the insulation you need, which will determine what materials you can purchase.


Choose the most effective insulation for a particular situation. The climate, existing insulation, and design of your home will all affect your decision, as well as those very important building codes.

Most Common Mistakes

Perhaps the most fundamental and often overlooked mistake do-it-yourselfers make when insulating is neglecting to find out the most efficient R-value for their area. Other common mistakes are listed below.

1. Inadequate Air Circulation

There are several places where leaving room for air circulation is crucial, such as around heat sources so your insulation does not melt or catch fire. Proper air circulation must also be maintained between the roof and the insulation.

2. Misplacing the Vapor Barrier

When using fiberglass batting, always install the paper side (vapor barrier) facing toward the outside, instead of toward the heated area.

3. Not Puncturing the Vapor Barrier or Doing it Incorrectly

Make sure you know in what cases your vapor barrier needs puncturing. Puncturing the vapor barrier unnecessarily, or neglecting to puncture the vapor barrier can cause problems with moisture getting between batting layers.

4. Not Using a Vapor Barrier at All

Do not omit a vapor barrier when using batting insulation as this prevents accumulation of moisture between the batting and the underside of the roof or wall.

5. Distorting the Fiberglass Batting

Take care that you don’t step on, compress or squeeze the fiberglass batting out of shape while you’re working with it.

6. Setting Paper-faced Batting Against a Heat Source

The paper-face of insulation batting is usually flammable, so be sure it is not set up against any form of heat source like a chimney or heating duct.

7. Not Getting into the Small Spaces

Try to fill as much space as possible with your insulation. Every gap will lead to leaks and a bunch of a little leaks can ruin the energy efficiency you’re trying to achieve.

8. Cutting Off Eave Vents

Don’t put any insulation over the top of attic vents or you will block airflow.

9. Not Assembling All Tools Before Starting

Make sure you have everything in the attic before you start to save yourself time and trips up and down the stairs or ladder.

All right, now you know what materials you need to insulate your attic and what issues to look out for while working. Part five will show you how to make sure your attic is ready before you begin.

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