Insulation, Radiant and Vapor Barriers - Insulation

I was wonering if you could give me the differences between the cellulose and fiberglass. I am getting information about each from installers and wondered if someone could give me a real persons opinion. I guess I should tell you that it would be going over about 5 inches of existing fiberglass that is 16 years old. Thanks in advance!

So I gather you are going to hire an insulation contractor to do the work for you....

With that in mind, Either product will do a excellent job for you....contractors who prefer fiberglass will talk down cellulose...and visa versa....

As long as they are guaranteeing you a specific R-value of additional insulation then you will get exactly that.

I would pick the contractor based on who I thought would give me the best workmanship, and price...


Good Luck

Jim

Well I think that we decided that really the price difference doing it ourselves was not enough really to bother with. Since you are so knowledgeable, let me ask you... Is there a difference in the insulation value? And is it going to matter if the cellulose gets wet? I mean I have a new roof, but the impossible can happen. It is nice to get your opinions! Thanks!

If you have a "R" 19 fiber glass(FG) insulation in the attic, that is about as good as it gets for FG, costs vs savings. Whether you go additional "R" 19 FG or cellulose the efficiency charts show that you will have about a 7.6 % increase in efficiency. The sales men will deny that such a chart exists, but it does. Since yor present "R"19 is saving about 80% of the energy that it can save you, you can see an additional "R" 19 will not pay for itself. Increase efficiency .076 x .20% ( the average amount of ceiling heat lost) x your winter bills. The is the best you can expect. You might not even get that. You also run the chance of increasing your A/C bills because the increased mass means more heat storage on summer days.

The most efficient method of reducing heat gain thru the ceiling is adding a radiant barrier on top of the present insulation. I have developed a very easy and effective method to do so. DIY.

Your run time on the a/c can be reduced up to 65%. In other words your a/c won't run all day. It could save you up to 12% on winter bills too. RB info, enter search engine, "radiant barrier" or "reflective insulation".

Check Sherwin Wms paaint store for "Radiance paint" You paint the inside of your exterior walls in light colors. Flat only. It's about 40% efficent, or, about, 4 to 8 times more efficient than FG.

If you have any questions, please ask.

Thank you for considering my opinion.

If cellulose were to get wet it would be more of a problem than if fiberglass were to get wet....

However If your attic was to get water in it and the insulation actually got real wet, the I would remove both types of insulation in the area where it got wet, Due to potential mold growth... So I believe that is a weak argument..

If cellulose is used it requires less thickness than fiberglas to achieve R-38 combined with your existing insulation. however it does weight more than fiberglass, which in turn may cause it to compact the fiberglass batt that is existing which will cause it to lose some of its effective R-value... Cellulose also settles more than fiberglass after it is blown in.. So as long as the appropriate amount is blown in so that after the settling has occured that You have a R-value of 38 you should be fine..


As far as RBISYS's comments on there is no benefit to go above an R-19, is nonsense... If that were the case why then in Michigan is it Law that new residential homes have to have a minimum of R-30 Insulation in attic areas...I have no problems with anyone promoting their products and ideas to help other people, but to continuosly try to downgrade your competitors product seems a bit redicules and misleading.

There are many studies done by all the various insulation suppliers... Cellulose, Fiberglass, mineral wool, and radiant barriers... Funny thing is no matter whose literature you read, their product is the best and they state their side of the argument...

I can't speak from practical experience with homes that are built in our Warmer States... However.. I have sold insulation for one of the leading contractors in Michigan.
(currently I am employed as an outside sales rep for a insulation wholesale supplier, We do over 500 thousand a month in fiberglass sales)
If you drive through any neighborhood a day or 2 after a fresh snow, you will see many homes with alot of snow which has already melted off the roof..then you will see an identical home with all the snow still remaining..

I would put money on it the home with all the snow has more than an R-19 and the home with the melted snow has R-19 or less.. This is caused by heat being lost through the ceiling area and warming up the underside of the roof and causing the ice to melt... You will not see that occur in a home which has been properly insulated to an R-38..

In addition lack of insulation more times than not is what causes all these ice damns and water damage...

Good Luck

Jim

Greetings, Alonte,

Regarding insulmans advice about "R" values, I rest my case, he is a fiberglass salesman". Unfortunately most fiberglass salesmen don't know much about, if anything, about the mechanics of heat gain/lose , except what the manufacturer wants them to know, and not know. They particularly do not know much of any thing about radiant barriers. It makes me shudder to think that a person actually goes out and tells some one they are getting a"R" 30, or what ever, when they know their product gets only about half of the manufacturers claim. Not only that, but you have the very serious, if not fatal, problems associated with fiber glass. 2-3 years ago Forbes magizine reported that the fiber glass industry has had over 80,000 lible suits filed against them. Why so, if the product is so good. You can find material on the internet regarding the horrible health experiences and deaths related to this material. I have no doubt that Wis. may have a "R" 30 requirement, the question is, how did they come by that. What industry was involved. The fiber glass industry has used the back door approach to maintain its existance, because if fair installed condition tests where applied to ALL materials fiber glass would probably be off the market.

Yes I do sell radiant barriers, for 29 years. And I have seen the damage and health problems associated with fiber glass. In fact, I too, am alergic to the chemicals and dust of fiber glass. So I make no excuse for sharing my knowledge and experiences with any one who is willing to listen. Only in America can products like fiber glass exist. Try buying fiber glass and installing it in Euirope.

I have seen enough homes where fiberglass was added and the home owner said that they saw no changes in their energy bills. In fact some studies have suggested that too much fiber glass can actually increase a/c costs due to the increase in mass that holds more heat energy that is radiated into the home for longer periods of time. My personal experience is that The radiant barrier will provide more energy savings than fiber glass.

Keep in mind that fiber glass is mostly air, aboput 98%.
Heat energy travels at the speed of light. How long do you think it takes for the energy to be felt on the opposite side of a 3 1/2" batt when a 250 watt heat lamp is placed above it? About 30 seconds. If you use two layers of radiant barrier, it takes about an hour to feel any change.

By the way I had one customer who over the years had added on and on to she got an "R" 45. Her house was still uncomforable and the a/c ran all the day and into the evening. I install a two layer radiant barrierin the attic and the a/c run time droped more than fifty percent. She said that not only was the house comfortable, the hall area that was particularly hot was comfortable for the first time in 30 years. You'll forgive me for being so wordy, but the fiber glass industry has been in control for too, too long. Home owners deserve something better. Much, much better.

Thank you for considering my opinion.

Okay, that is a lot of information. I will take it into consideration. It is funny, my father is in energy management and I just wanted someone else's opinion. I really appreciate all the help. I think in a lot of ways, you helped me make sense of it all.

Thanks...
Leigh