A quick primer in Insulation.
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 because while it isn’t common in an attic area, it can be expensive for what it provides. Suffice it to say you aren’t going to 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. A – It has to be used in conjunction with blown-in insulation (see below) and 2 – its performance falls way short of the advertised performance for that product.
Plus it is expensive. Way too expensive. And it doesn’t keep heat out of your attic. Plus it is expensive – did I mention that already?
If you are curious about radiant barrier next time you are wandering around a big box store check out the price of a roll. Compare that to what the barrier companies advertise to do your attic.
You can do way better for the same money.
Keep in mind you need about R49 in your attic to meet what is widely regarded as industry standard. Ok – here we go. Let’s start with…
#5 – Batt insulation. You know what this is although you may not know it by name. You have seen TV ads where the Pink Panther kicks this stuff around and it unrolls in the attic.
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.
Viola! You are the king (or queen) of batt insulation.
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. Mmmmm, even more snuggly…
Warning: You must remember this – you are working in your attic. Those joists are less than 2” wide. You are not gymnast Simone Biles. 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. Seriously), and a cup if you are especially clumsy.
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.
#4 – Cellulose insulation. 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. 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, albeit a dirty, dusty one (can’t say that enough). 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:
#3 – Blown-in fiberglass insulation. 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. So don’t.
Don’t make me stop this blog. You kids put that insulation down right now…
Ok – same routine as with the cellulose – one person runs the loading, 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, which is nice.
The bad part here 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.
Warning: You must remember this – you are working in your attic. Those joists are less than 2” wide. You are not the Soviet gymnastics team. Not even close. 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. Seriously), and a cup if you are especially clumsy.
#2 – Hybrid. 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 (yes, there will be leaks) and then caulks the leaks around the windows (you could do that yourself) 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.
Check it out. It will make you smile.
#1 – Spray in foam. 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 allowing you to store more junk in your attic between the Christmas lights that are all knotted in a wad and the suitcase you used in 1976 when you took the bus to visit your aunt in Kokomo.
Also – added benefit! If your hvac system is located in your attic, this is the best way to go. Period.
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.
And who doesn’t want to be in a better working environment.
The best part about insulation is the money you will be saving on heating/cooling your home. Even better - insulation has a payback period (your mileage may vary).
It is probably the best place to start that list of home improvements.