Replies

1. 
   Guest_ | Mar 16, 1999 08:22pm | #1

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   (a) this should be in the energy thread;

   (b) i hope this Q won't set fire to the interminable cel/fg debate here;

   (c) use blown-in cellulose -- its R-value will not decrease with compaction, it will help seal air loss through the ceiling & unsealed wall plates -- speaking of which, first take the time to seal all air bypasses to the attic (chases, access doors, ceiling light cans [mindful of fire hazards], penetrations, HVAC ducting, etc. ... BTW fg filters but does nothing to stop air flow, which is why is so often becomes filthy);

   (d) search this site for info on fg and cellulose (& cellulose v. fg) -- you will find more than any sane person would want to know.

   Is this enough of an answer folks? Pretty please?

1. 
   Guest_ | Mar 16, 1999 10:32pm | #2

   *Jim. The R-value of low density blown-in fiberglass does drop as much as 50 percent as the temperature gets to 18 degrees belwo zero. And even at 10 degrees F the R-value drops but only by about 25 percent. This seems to be less of a problem with high density fiberglas.I am no fiberglas lover. But fairness requires that we recognize that there are not that many states in the US where the temperature is Zero or below for days on end. Even Bismark, North Dakota has only 278 hours during which the temperature is 2 degrees F, and only 80 hour during which the tempersture is -18 degrees F.The question then, is so what if my figerglass insulation R-value drops 50 percent of its R-value? What is the effect on the annual heating bill? Sixty dollars or less. By the bye. This is not a problem with cellulose insulation. And if you have fiberglass insulation installed and are worried about the problem, blow-in cellulose over the fiberglass insulation to stop the convection that causes the R-value drop.If you are starting fresh, before you install any insulation in the attic do the following: go into the basement and seal all the holes and openings in the basement ceiling. Now do the same thing t the ttic floor. Seal between the top plates and the gypsum board with foam. Seal between the metal csing of the bathroom exhaust fan and the gypsum board. Now call in the cellulose insulation contractor.Sealing these basement ceiling and attic floor openings significantly reduces (a) tha leakage of warm moist air into the attic space; (b) is the first line of defense against ice dams; (c) lessens or eliminates the need for attic ventilation. The cellulose puts your mind at rest since celluloe suffers no no R-value drop with falling temperatures. Cellulose's added bonus, not readily available with fiberglass, is a cooler house in the summer. GeneL.

1. 
   Guest_ | Mar 18, 1999 07:51pm | #3

   *FredL. Right on as usual. GeneL

1. 
   Guest_ | Mar 18, 1999 10:46pm | #4

   *Brevity. Cool.