What is Correct Insultion to use?
In exterior wood stud bay walls what is the correct insulation to use. I live in upstate NY, and it gets a might chili here in the winter. One hears use unfaced in the walls with a poly vapor barrier. Someone else says use the foilback or Kraft face insulation. Who really out there knows which one is right? and if the unfaced is the correct choice with the poly, why? what is the advantage over the Kraft face or foil faced? I am always willing and eager to learn….Thanx……BigWhit
Replies
BW, suggest you use closed cell polyurethane spray foam. Fiberglas is not very air tight. You have the choice to pay now (foam) or pay forever with fg and high bills.
You can search this web site for volumes on insulation. Some prefer wet spray cellulose, others prefer foam. But in both cases, sealing out air flow is the important part of insulating, and rarely is it accomplished with fg roll, batts or blown loose.
Paul
Neither.
The best insualtion is a sprayed in place foam, Icy or Urethene
After that, you would look for blown in Chopped fibreglas or cellulose with plastic VB
FG Batts are way down on the list of what is best to use. They allow too many convection currents within the wall cavity, especially on windly days.
But if your only choice is one of the two, both have a VB, The Kraft or the foil, and if the unfaced is covered with visqueen, it has a VB too.
once upon a time, the foil was considered better bnecause of the reflective surface to turn radiant heat back into the room, but tests show that once you cover the foil surface with wallboard, you no longer get any good out of that.
if your sheetrocker wants to glue the boards to the studs, he won't want the plastic there, but the proper way to install batts is with the flaps over the inside face of stud anyway to get your VB anyway.
read up on the insualtion discussions in this folder for an education.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
This is new work, not retrofit, right?
Ask 10 people and get like 16 opinions (or more).
Mine: Airtight drywall approach with dense pack cellulose, or wet spray cellulose. No VB.
Cost/benefit ratio is better than with pricey foam.
Edited 4/5/2004 4:12 pm ET by csnow
Some of those oddball insulations may be hard to find in some areas. Fiberglass isn't so bad. I built a 2900 square foot home in St. Lawrence County (on the Canadian border). I used R21 instead of the standard R19 in 2 x 6 walls. It's denser and there is very little air movement. Along with an insulated basement and good windows and other care, the house cost $899 to heat for a year with natural gas. That's pleanty cheap enough for me.
Any of the three options you mentioned are satisfactory, but using unfaced insulation combined with a poly vapor barrier is better, because it's quite a bit more effective at reducing air infiltration than a vapor barrier on each strip, because you have many fewer seams. A house wrap (such as Tyvek) on the outside reduces air infiltration even further.
In the attic, blown in insulation can be applied much better than batts which eliminates missed spots, and can be piled in deeply very quickly.