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titan7 02-26-2011 11:08 AM

did I use the wrong insulation?
Live in southern ca, did a kitchen remodel and replaced som windows with new constuction nail on windows. We also replaced some drywall and insulation. The construction of the home is exterior stucco, with black felt paper and lath behind it. The original insulation (33 yrs old) looked tired after the the plumbing and electical work so we replaced some of it that looked hammered. Inspector said R-13. We picked up some Owens Corning R-13 from Home Depot, kraft faced was all I could find anywhere in So. Ca. I called the Mfg they said use the kraft faced with the paper facing the interior of the house. My question is why did they not use faced insulation in 1978 when they built the house? Also I am not concerned that this type could create a moisture issue? We did not staple the edges of the paper to the studs, the inspector said it was fine to just push it in? I guess it does not matter now since the walls are closed, painted and cabinets are installed.

jklingel 02-26-2011 05:02 PM

in s cal, it probably matters little that there are air gaps at the studs. in heating climates, that would make a difference. that said, if you run a/c, those gaps will not help. the foil vs unfaced is a choice; some like the "vapor retarder" benefit of the faced, but it isn't much, IMO, if you don't do a super job of air sealing the edges. unfaced is built fatter so that it fits better; "friction fit" is another name. either way, fiberglass is not a great insulator anyway. it is ok, but not great. you'll be fine in your area. j

titan7 02-26-2011 06:44 PM

Thanks, most people were telling me in So. CA is does not matter. in the dead of winter we may see 40 on the absolute coldest night. Most of the time it's 48-53 at night and 60-65 in the day in the dead of winter for a couple weeks at most. Low 50s at night low 70s in the day is usual for winter. Summers avg 82, perhaps 95-100 for 5 days in aug.

jklingel 02-26-2011 09:20 PM

All that said, I am certain it is still advisable, should you reno again, to properly air seal and to avoid true air barriers. enjoy your temps; -5 here. j

titan7 02-26-2011 09:33 PM

What's proper air seal and avoiding an air barrier?

jklingel 02-26-2011 10:15 PM

Air leakage is the primary mechanism by which moisture gets into a wall. A one sqr inch hole "typically" lets in as much water vapor as what diffuses through a whole sheet of sheet rock, making penetrations into walls risky. Canned lights, electrical outlets, fans, etc, that puncture a wall or ceiling need to be impeccably air sealed (goos, tapes, etc). Obviously, heat also goes out with warm air. In hot areas, hot air will come in if there are other holes to let other air out. Vapor barriers don't let moisture through. Aluminum is perfect. 6 mil visqueen (polyethylene sheeting, as often put around potted plants, sometimes in walls and ceilings) has a permeance rating of 0.06, so it won't let much through. It used to be recommended that visqueen be installed under the sheet rock to keep moist air in the conditioned space from getting into the walls, condensing, molding, etc. It is generally NOT recommended in most places any more, exceptions being zones 7 and 8 (very cold) and some hot-humid places where it can be recommended on the OUTside. It is still used, and still advocated by many people, but the general consensus in the building science community is to be very cautious of its use, instead depending on air sealing. In places that get hot enough for air conditioning usage, the visqueen under sheet rock can cause solar driven vapor to condense on it, giving you wet insulation, walls, etc., or, mentioned a cat in southern Ohio whose building business was going gung-ho until he used visqueen under sheet rock (brick veneer outside, which holds tons of rain water) and then people starting turning on A/C. Wet carpets, etc. He folded up quickly. He ain't the only one with problems. Not everyone has trouble; I don't, but too many people do. In my new house, I won't install visqueen, even up here in the cold. Walls need to breathe, so that any moisture that does sneak in, and some will, can also leave. Visqueen is just risky, IMO. Read on the sites I mentioned, and elsewhere, and draw your own conclusion.

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