View Full Version : attic insulation
11-06-2006, 08:33 PM
anyone heard of adding blown fiberglass insulation over blown cellulose to increase r value.
11-06-2006, 08:40 PM
how much insulation do you have now?
at some point, adding more insulation ain't going to help.
another words, if you have 18" of insulation, adding another 12" isn't going to do anything for you ~~~~other than make your wallet lighter.
11-07-2006, 02:49 PM
why do you want to change?
are the ceiling joists covered? -- they should be!
get quote from insul contractor for both types
11-07-2006, 02:57 PM
Fiberglass is lighter so fiberglass over cellulose is better than the reverse, which will cause the cellulose to smush the fiberglass. As long as it's done properly I don't see a problem. But you must make sure you don't block soffit vents or blow it over light fixtures that aren't rated IC for insulation contact.
11-07-2006, 06:25 PM
reason for change is. i heard all the debate about cellouse and thought if i were going to add insulation i'd add fiberglass rather that remove all the cellouse.
11-07-2006, 07:12 PM
again!!!!! how much insulation is all ready in the attic???
11-07-2006, 07:52 PM
9 1/2 inches of cellouse, home is s.c.
11-07-2006, 08:30 PM
I put cellulose over fiberglass in my 5 homes over 40y -- easy to install, cheap, packs tight to have fewer edge cracks, fireproof.
without careful workmanship, the edge cracks of fiberglass batts probably equate to 20% losses.
I think that I would rather have fine cellulose in my lungs than fiberglass = plant cells vs glass stings for any passing around my N95 mask [ with a quick exhaust ]
BTW, use hardware cloth with 0.125" openings to keep out insects. I also put a second one with 0.375" openings to keep out critters. -- at my attic vents that are just cut into wood siding.
11-07-2006, 09:07 PM
Originally posted by fishin
9 1/2 inches of cellouse, home is s.c.
so you have R-30 now? what is your goal? R-38? or more
You might want to add another 6" to 12" but anything over that and your going to be wasting money. Like I said at some point you can only add so much insulation before it's not doing anything for you.
Maybe a powered attic fan would be doing more for you than more insulation
11-08-2006, 12:42 AM
i recently added about 10in of cellulose on top of the 6in of the pink stuff but before that i got a can of low expansion foam and went around all the pipes and vents and and then added foam vents through out the attic. i rented a machine and blew in 38 bags in about 3 hrs.i priced it to be done but that would have cost me $1700 after doning it myself it cost about $700.Theres more prep time then there is actual time to blow in ,dont forget to check the seal around your doors and windows and get the plug gasket for the outlets around the outside walls.Theres many was to get house energy efficeint TAKE YOUR TIME AND PLAN YOUR STEPS
11-08-2006, 09:09 PM
john smitty, after adding 10' of cellouse can you tell a difference in comfort and utility bill?
11-09-2006, 12:52 AM
Hi to answer your ? yes, i did this in jan this year before i had my lennox g61v installed so i did see and feel the difference because or gas went up and my budget was $133 and it went to get ready $134 please remember to also do the other things it all adds up. i had my house e-tested through the canadian government and my house was rated at 69 before i did any work and i had a air loss of 227 and after it was tested again it rated a 76 which was a rating of a new efficient house and the air loss was down to 77 .The guy that did the test was impressed. NOW I GET TO ENJOY THE FRUITS OF MY WORK.
11-09-2006, 01:45 AM
Adding more insulation will result in insignificant savings. Concentrate on windows, air sealing and wall and basement insulation.
Download hot2xp and model your home's heat load here:
11-09-2006, 12:13 PM
After doing the e-testing on the house i found out there was a 20% heat loss through the roof, heat does rise but the place where you loss the most is the basement which is rated at 30% heat loss thank GOD my basement is finished.
11-09-2006, 06:29 PM
Heat does not rise. Heat dissapates in any direction to a lower level of heat. Hot air will rise above lower heat air. Basements per square foot of surface tend to lose less heat to the surrounding earth than the upper levels of the house to the surrounding air. Less insulation is needed in basements than upstairs.
11-10-2006, 01:03 AM
well well well so what your saying is that the canadian government stats aren't true in the slightest then hows my house more eff then ever????? and why would they even have a program for eff??
11-11-2006, 09:03 PM
Johnsmitty---you didn't read what I said.
11-14-2006, 10:14 PM
brother just playin with you thanks for the info
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