Insulating your attic is the most effective way to improve the efficiency of your home. Heating in the Winter time and cooling during the Summer time becomes easier for your heating/cooling system. I noticed on average a 30% to 40% reduction in the energy that my home used after installing attic insulation.
How Does Attic Insulation Work?
Heat flows naturally from warmer areas to cooler ones. It does this by one of three different methods: conduction, where heat is delivered directly from one mass to another; convection, the transfer of hot air from one space to another (hot air rises, cool air sinks); and radiation, which simply means that any warm mass passes off heat toward a cooler one.
The main function of insulation is to minimize the radiation and convection effect of heat and minimize conduction. A green energy barrier works in conjunction with insulation helping our home to stay warmer in cool weather and cooler in warm weather.
What is the Best Attic Insulation Type?
There are many different types of attic insulation, but the best type depends on your climate and needs. Two things that you will be looking for is the material used such as cellulose and the r value or “resistance to heat flow.” The more extreme the range of temperatures in your area the higher insulation r value you need. You can check your local energy commission, local power company, or local home center for the best R-value in your area or consult this map and chart courtesy of the EERE of the Department of Energy.
Insulation R Value Map
Insulation R Value Chart
Blown in Attic Insulation
Blown in insulation, as opposed to batt insulation which uses fiberglass blankets, creates a seamless blanket of insulation in your attic. You could spend hours kneeling to achieve the same result with fiberglass batts in your attic. Once installed and expanded to the uniform thickness, batts offer a known, consistent R-value. However, blown-in insulation thickness can vary in an attic space which leads to non-uniform R-values. Cellulose is a common and advantageous type of blown in insulation. One of the main advantages is its fire retardant characteristics.
If you decide to use blown-in insulation, place scrap lumber depth gauges throughout the attic. These pieces of wood can be marked to the desired thickness of insulation. Tack them to the ceiling joists in various locations and use them as guides for desired depth.
Attic Insulation Installation
An installation of insulation in your attic shouldn’t take more than a full day. The first step is determining how much insulation you already have in your attic. It may be none at all or just enough to fill in the floor between the joists. Either case is an indication that you don’t have enough insulation. The best way to find out if you have enough insulation is to measure. You need to have about 18” of loose fill insulation on the attic floor. That should give you about an R-60 value.
The next step is to prepare for your project. The first thing you need to calculate is how much additional insulation you are going to need to get to the desired depth. Some of the basic tools you will need are protective clothing, a dust respirator, gloves, goggles, full cover pants & shirt, lighting, and a ladder if necessary to access the attic. Obviously, you will also have to purchase all the insulation necessary to cover your attic. Sometimes if you get enough at stores like Home Depot or Lowes they will throw in the machine for free. Once you have everything prepared to install, you will be ready to get up in the attic.
It is recommended that you lay out some temporary flooring across the joists to provide safe and easy access to all the areas of your attic. The best method of blowing in the insulation is to start at the outer edge of the attic space and work your way back to your attic access. When working on the edges, you need to ensure that you fill far enough to cover the tops of the exterior walls, but not in the way of the flow of air from the eave vents. Make sure that you don’t insulate over light fixtures that are not rated I.C. (insulated ceiling) because it could cause a fire. It is usually helpful to have two people for the job – one operating the gun and the other loading insulation in the machine. Make sure to load slowly into the machine to avoid clogging it up. Everything else is pretty straightforward. After you have a proper layer of insulation in your attic, you can expect to see your energy bill drop pretty substantially.
October 29th, 2009 at 11:25 am
Great information about Attic insulation. I have recently changed my ceiling as a part of home improvement. I have been looking for information about attic insulation for long time, finally got it here. I will go for attic insulation this time for sure. I will follow the tips given here for attic insulation. Anyway thanks for the information.
November 17th, 2009 at 1:49 pm
Very well said, thanks for sharing. I think that its important to have proper insulation for not only your attic, but your entire home. With the winter months upon us, having proper and effective insulation can save a lot of money in heating bills.
February 12th, 2010 at 11:26 am
Great article. I know a buddy of mine has an older house and you can really tell the diference between his and mine just from the insulation. His heating bills are way more than mine and you can really feel the drafts throughout the house.
April 13th, 2010 at 11:09 pm
Great information. At first I was kind of skeptical, but after reading through most of the article, it made me realize new ideas in which to rennovate our house. However, like the others stated, it would be better if the whole house had better insulation rather than just the attic itself.
April 15th, 2010 at 4:32 pm
My husband & I just recently started storing in our attic & we have vaulted ceilings so we can see ALL the places we need to insulate & even hang drywall. Thank you for the helpful tips & advice! Hope we’ll see a change in our heating bill too!
May 23rd, 2010 at 8:39 am
I’ve heard that there is a variation of fiber glass insulation that comes in lengths encased in an envelope of clear plastic such as polyethylene. I can’t find that anywhere. Do you know what I’m talking about and can you direct me to manufacturer or retail outlet? This is to replace or add to R19 attic fiberglass already in place.
July 12th, 2010 at 11:29 pm
(This was last year) I live in Houston and for the past few months we have had our thermostat at 73 degrees. At about noon you can start feeling the heat. At about 6pm it got about 80deg and did not reach 73deg till about 8pm. My first light bill was $500. My secound bill was $550. I nearly died. My wife and I did some research and decided on cellulose. Everything we read about cellulose was all positive. Anyways we blew insulation on top of our old insulation (we have about an R-60 rating now) all for a fraction of what other types of insulation costs. We have a 1800sq house and I believe we spent about $600 maybe $800. Well its been exactly a year later and what a differance. What ever temp I put it at stays at what I put it at. My light bill???? Well my light bill for June was $208(compared to 500) and for July was $273 compared to $550. This was the best thing I have ever done for my house.
July 12th, 2010 at 11:33 pm
Another comment. Just be careful not to cover the soffits. After a friend explaining to me their purpose (they provide aiflow into the attic) we had to go back and clear them.
July 26th, 2010 at 2:05 pm
How long until you notice the difference? I insulated my home Saturday July 24, 2010 today is Monday July 26, 2010; should I feel the difference already?
August 9th, 2010 at 8:22 pm
Great information. Thinking about undertaking a home renovation and I’ve been browsing blogs all month long. Thanks for the info.
October 29th, 2010 at 6:27 am
My home is 53 years old wiyh 8′-10″ of cellulose insulation between the 2×6 joists. I want to continue to use the attic for storage so will add toists to add R38 batts under the floored area-don’t want to have airbourne particles during installation so blown-in is not an option. The ceiling in my house is 7/8″ thick drywall- sheets of 1/2″ + 3/8″. There is no vapor barrier under the cellulose. Have never had a moisture problem. Questions- In the unfloored areas, can I add batt/faced insultion cross wise over the joists filled with old cellulose? Do I need to add vapor barrier? I’ll move excess cellulose to perimeter attic space.
November 29th, 2010 at 6:45 am
Great info guys. Thanks a lot! My home really has great insulation but it would be much better if the insulators that I put in were thicker because sometimes, my whole attic gets hot from the sun. So, I think that I will improve my attic for better insulation. =)
January 6th, 2011 at 1:29 pm
So glad to see this topic being addressed so well like this. I can give a reassuring word to the 30-40% savings you can see with just simply insulating your attic properly, I have seen my bill down by 38% with the application of spray foam in my attic over the past six months.
February 2nd, 2011 at 3:56 pm
What is the useful life span of batt insulation?
We have a condominium building that has six attic areas and all have a peak roof and the current insulation has been installed since 1981.
Does the thickness (R-rating) have anything to do with the life span?
Thanks in advance for a reply.
February 21st, 2011 at 2:34 pm
I don’t see how you could walk around safely or store stuff in an atic with 18 inches of insulation. What am I missing?
March 22nd, 2011 at 7:27 am
good info
April 5th, 2011 at 1:55 pm
Actually Daniel if your attic is getting heated from the sun, you should consider a radiant barrier, which works with your existing insulation. Check out this article on green energy barriers for more info.
April 12th, 2011 at 11:40 am
When you install a radiant barrier the effects are immediate. Radiant barrier reduces the surface temperature of your insulation, which is what amounts to a cooler home. If you don’t have a radiant barrier then you’re allowing any heat radiating off the roof to heat up the insulation which in effect is creating a warm blanket wrapped around your home. In the summertime this is the LAST thing you want to do. The key is to keep the insulation cool in the summer and warm in the winter – this is why green energy barriers work so well.
April 12th, 2011 at 11:54 am
In a vented attic you ALWAYS want to use a perforated product (NOT a vapor barrier) – you don’t want to trap moisture, you want it to flow freely and evaporate.
April 12th, 2011 at 12:14 pm
This can vary depending on the type of insulation and the install method. Generally if moisture hasn’t disrupted the insulation, settling/compression is the only major change over the course of time. Both settling/compression can decrease the R-value of insulation, but typically if the insulation is dry, doesn’t have any foul odors and it hasn’t settled dramatically, then it can last the lifespan of the home.
April 12th, 2011 at 12:24 pm
Are you talking about Polyethylene vs. Standard Fiber Glass insulation? The typical application for that product is on pipes/ducts. What is your intended use for this material and how did you hear about it?
April 12th, 2011 at 1:37 pm
You could walk around IF you put in some walking boards to move around. As far as storing stuff that would be difficult if there is a ton of stuff to store (or larger items to store).
April 16th, 2011 at 1:37 am
Adding insulation your house is an expensive operation but can help greatly to reduce heating bills.
July 3rd, 2011 at 10:23 am
Does insulating a house also help with the heat in the summer? We have a house with a large front room with large windows. It gets hot in the summer and then the heat travels up the stairs to the bedrooms. We don’t have or want air conditioning.
July 14th, 2011 at 2:16 pm
Radiant barrier is your first line of defense and traditional attic insulation (fiberglass or cellulose) is the second line of defense against heat gain in your home. Radiant barrier addresses RADIANT heat, while traditional insulation addresses CONDUCTIVE heat. If you are trying to reduce the heat gain in your home, you really do need BOTH.
August 8th, 2011 at 8:22 am
I live in the SW and have a tile roof. My house is stucco and about 10 years old. The blown insulation in the attic is about 10 inches deep. The insulation in the attic is only over the inside of the house. There is no insulation over the attached garage or the front porch area. Should I start by putting insulation over the garage ceiling? Will the radiant barrier help with a tile roof? If you have gaps in the radiant barrier (places that are too hard to get to) or gaps in the attick insulation (over the garage) are you mitigating/negating the positive impacts of the existing insulation?
August 8th, 2011 at 10:08 am
Proper attic insulation is a great start to making a home more energy efficient.
August 20th, 2011 at 1:15 pm
Having lived in Wisconsin for years, I’d definitely recommend blown-in insulation for anyone in a cold climate.
August 22nd, 2011 at 5:07 am
The attic insulation is very expensive, but it is cut your montly bills a lot. I made it for my house. combination with solar cells and solar water heater, now I heating my house almost free.
September 3rd, 2011 at 1:22 am
Keep it up, your post is so good that many readers will learn a lot from it. I will wait for your new updates. Thanks.
September 9th, 2011 at 9:52 am
Insulation over a non-conditioned space is not necessary at all. If you are trying to temper the heat in those areas, your best bang for the buck is to go with a radiant barrier foil. If you are trying to keep the whole garage cooler, you’ll want to add a radiant barrier to any walls catching direct sunlight (this includes the garage door). With the roof, as long as a radiant barrier is properly installed (with an air gap) then it works on ANY roofing system. And yes, partial coverage with a radiant barrier works. Take a look at this video to learn more about partial coverage and benefits: http://www.atticfoil.com/video-faq-partial-radiant-barrier-coverage.htm
September 30th, 2011 at 12:13 am
nice article about home improvement
October 22nd, 2011 at 8:36 pm
Great article. It should be noted that another important step before installing insulation is air sealing. Sealing all the gaps so that air does not move through the insulation will make the insulation more effective.
November 2nd, 2011 at 11:45 am
I can’t wait to do this this weekend in my attic. The a/c constantly stays on in these dcrazy hot temps here in Louisville. Hopefully its cool enough in my attic right now (11/2/11). My buddy and I will use walkie talkies with the loader and me doing the hard part on my knees in the attic. Actually I don’t want to to do this now because its gonna hurt the knees but I have to because my wife will hurt me more than my knees will hurt. Oh well can’rt wait for lower bills; everybody says it makes a huge difference to do it yourself, blown in insualtions and the loader machine is free rental from Home Depot w/insul. purchase
January 5th, 2012 at 11:01 am
Yes, Insulating your attic can definitely help cut utility bill costs.
February 1st, 2012 at 3:30 pm
Cellulose is approximately three times denser then fiberglass. This can help deaden the sound through walls and between floor levels.
March 15th, 2012 at 10:41 am
Like admin said above Radiant barriers are great for knocking down attic temperatures. We have observed 25 degree reduction in attic temperatures after installation of radiant barriers in southern climates.
March 29th, 2012 at 5:33 am
True, the type of insulation installed depends on several factors like your climate. But radiant barrier is ideal for many attics, as it helps your home’s ability to reflect (rather than absorb) energy from the sun.