Here are 5 forms of popular insulation, from least expensive to most expensive which also, coincidentally, corresponds to their over-all effectiveness in the same order.
One quick note – I am leaving out Styrofoam and radiant barriers. Styrofoam isn’t common in an attic area, it can be expensive for what it provides. You don’t want to do your entire attic with Styrofoam boards.
I leave radiant barrier out also because I am just not a fan of radiant barrier. It has to be used in conjunction with blown-in insulation and its performance falls way short of the advertised performance for that product. Plus it is expensive and it doesn’t keep heat out of your attic.
Let’s start with…
You know what this is although you may not know it by name. This is the least expensive, easiest DIY insulation project there is. Measure your attic, buy enough rolls to fill the measured area, open the rolls in the attic (don’t open before you go up there lest they begin to unroll which makes this job 1,000 time harder), place rolls between the joists and unroll.
When one roll ends start the new roll there. When you get to the end of the joists cut the insulation and begin between the next joists over.
If you really want to do it up roll out a second layer perpendicular to the first layer after you have installed the first layer.
You can expect an R value of around 3.25 per inch here so you will need about 15” of batt insulation.
Oh one other word here – get the batt insulation without the vapor barrier on it.
Cellulose insulation is made up of 75-80% shredded paper (generally newspaper) and 20-25% fire retardant materials.
It can be a DIY project, but it will be a dirty and dusty one. It is really dirty and dusty, so much so, that I would recommend you wear a respirator and not just the disposable dust mask.
This is also best DIY’ed with a couple of people, one to feed the insulation into the blower and one to point and shoot the blower in the attic. Please read and follow all label directions.
You can usually rent a blower with a minimum purchase of bags of insulation.
This is a good insulation. While it will eventually “settle” it can easily be stirred back up again by, say, opening your attic door and entering the attic.
You can expect about R3 value per inch of cellulose insulation so you will need a little over 16”.
This is closely related to:
Fiberglass insulation is made with plastic and small fibers of ground glass.
This is the insulation that looks like cotton candy, only don’t touch it without gloves on. Don’t sit or allow your children to lie in it. Don’t play in it. You will itch for a long, long time.
Same installation routine as the cellulose, one person runs the loading and one runs the business end of the sprayer. The bonus here is that blown-in fiberglass is nowhere near as dirty and dusty as cellulose.
The bad part is that the fiberglass will settle over time. Settling causes R value to diminish. So, 20 inches of fiberglass today is R50 (blown-in fiberglass R value is about R2.5 per inch which means 20 inches is needed) but 5 years from now if you only have 17 inches due to settling your R value is only R42.5, and it only gets worse.
This is a combination of spray-in foam and blown-in insulation.
An insulation professional comes to your house, runs a blower door test on your house to determine where the leaks are and then caulks the leaks around the windows and foams the bigger leaks in your attic. Then blown-in insulation of your choice is added and your house is good to go.
This is rather new and sits in a nice spot being not as expensive as a total foam job, but better than just a blown-in job.
Debate rages on back and forth between closed cell foam vs open cell foam in your attic, but either is as good as it gets.
This is not a DIY yourself project, so hire a qualified professional.
Foam is sprayed into the rafters in your attic. If your HVAC system is located in your attic, this is the best way to go. It will help keep your system warmer in the winter and cooler in the summer, thus allowing less heat/cool loss in ductwork and a better working environment for your system in general.
The best part about insulation is the money you will be saving on heating/cooling your home and It is probably the best place to start that list of home improvements.
Warning: You must remember this – you are working in your attic. Those joists are less than 2” wide. Take proper care in moving about your attic. Wear long pants and long sleeves, gloves and at the least a disposable dust mask, you may want to step it up and wear a respirator with filters for some of this work.