How To Insulate A Attic | Do It Yourself

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How To Insulate Your Attic With
Fiberglass Batts or Blankets

Alan K. of Anchorage, AK wrote:

Dear Itchy,

I've got an addition that needs insulating. The sheetrock is already hung on the ceiling and I want to install fiberglass blankets on the ceiling. What's the easiest way to do it?

Well, the easiest way to insulate a ceiling is before the sheetrock is hung, but it's too late for that now. They call me "Itchy" but they're gonna call you "Itchy" also when you get done with this one. Here's how you do it yourself:

Measure the distance between the ceiling joists to figure the width of batt insulation you'll need. Most are framed either 16" or 24" on center, which means you'll need either 15" or 23" fiberglass blankets. Next measure the square footage of the attic area to determine how much insulation you'll need to buy. Finally, figure out the r-value you'll need, R-30, R-38 and so on.

You had better get your long sleeve shirt on and don't forget a dust mask and goggles because, boy howdy, you're about so have some fun now! Most R-30 and R-38 insulation batts come in a bag and are 4 feet in length. The problem is the bag won't fit through most attic access holes. That means that you're going to have to open them downstairs and feed them through the access hole one at a time. You might want a helper for this. Try not to hug these things to much as their coming through the hole.

Once you've stocked your attic with insulation you want to start at the far end and work your way back to the access hole. With the kraft faced vapor barrier facing the heated area lay the batts between the ceiling joists. Try not to mash them down as it lessens the r-value. Make sure each batt fits against each other with no gaps. When insulating near eave vents be sure to allow at least 3 inches of clearance and the same for any heated fixtures such as lights and door bell transformers.

You'll need to make cuts so the insulated blankets will fit in certain areas. The easiest way is to measure your cut and place the batt paper side down on plywood or even a ceiling joist and cut it from the fiberglass side with a utility knife. Use scrap pieces of insulation to fill any gaps or spaces.

Remember safety first. You can lay a sheet of plywood down to use as a work platform in the attic or you can walk the ceiling joists like I used to do. Whatever you do, don't try to walk on the sheetrock or you will soon find yourself downstairs wondering why you did that fool thing. Believe me, I've known a few people in my time that learned not to walk on drywall the hard way.

When you're done climb out of the attic and don't forget to insulate the attic access door. I used to staple it directly to the door but I wouldn't recommend it if you don't know what you're doing. It would probably better to just glue it into place.

Finally, get out of those clothes man! By now you've probably got some good itching going on and you better take a nice warm shower.

Related Tips and Advice:

How To Insulate Knee Walls
How To Insulate An Unvented Crawl Space
How To Insulate A Floor In A Vented Crawl Space
How To Insulate Wood Stud Walls
Adding A Plywood Attic Floor Over Insulation

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