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We have a little disagreement in our office, Is it required or do you need to install a vapor barrier over fraft faced insulation in new construction?
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yup... the kraft paper laminate is a good vapor barrier.. but the edges allow so much penetration that the kraft doesn't do anything...
so if you want a vapor barrier, use a continuous 6 mil poly, lapped onto the ceiling and the floor, after the board is hung, you can trim the poly sticking out on the floor
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Mike,
by installing a 6 mil vapor barrier over the kraft, would this allow moisture to build up between the two? and have mold grow?
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Nope... wher's the moisture cummin from?
how did it get BETWEEN the two vapor barriers?
the real point is that the kraft faced , even if meticulously applied to the face of the plate, shoe, and stud....has still got a lot of edges to pass moisture thru, not to mention around the penetrations, like electrical devices, etc..
the poly can be form -fit, and taped...
and the kraft will hide a lot of the gaps in the insulation so it can't be inspected for good fit of the insulation itself..
we use unfaced fiberglass batts and 6 mil poly...
of course, we use cellulose whenever we can , instead of the fiberglass
*Jim,
View Image © 1999-2000"The first step towards vice is to shroud innocent actions in mystery, and whoever likes to conceal something sooner or later has reason to conceal it." Aristotle
*joe...u didn't say..((((respectfully))))disagree with Pogo...he's yur elder and yur better...BTW.. if the framing is wet... and the kraft is installed PROPERLY, ie.. stapled to the FACE of the framing.. then the moisure is going from the framing into the insulation... not to the face of the kraft laminate.....i already said i wudn't use the kraft faced, i'd use the unfaced.. but if u do i wudn't trust the kraft system as a vapor barrier..and by the time u tape every seam on the kraft.. u wud hav ben way ahead with the 6 mil poly over the kraft...hah, hah, hah...b been there too many timesKermit
*Why does anyone still use kraft faced insulation?It makes for a lousy barrier. If you've ever seen a blower door test, you wouldn't ask where the moisture comes from. It comes from all the air moving through the walls. Are all your outlets sealed? (Unless you used a Lesco box behind your outlet box they aren't.) How about all the holes the mechanical contractors cut and drilled? What about all those holes that got poked in your poly before drywall?
*Kraft faced is not the way to go IF you are wanting a vapor/moisture BARRIER (and who isn't). Kraft face is a moisture RETARDER, not a barrier. It allows moisture/vapor to pass through it (one way). This is why the paper is supposed to face the heated room, not the outside (or in the case of an attic, the attic side)So sayeth Owens-Corning and Certainteed.Just a thought...James DuHamel
*james, yur still one a my favorite guys in the world , er at least the breaktime world... but yur fulla crap on this one.. (IMHO)the kraft is almost identical in its passage of moisture thru it ,, it has just a bout the same qualities as poly in that regard (say 4 mil, though, not the 6 mil).. the problem arises if you install it backwards, the moisture goes thru the insulation and gets trapped at the kraft laminate surface, and the if conditions are right it condenses, and a moisture problem starts...its a bad vapor barrier for just two reasons, it's not flexible, so its difficult to make it conform to irregular shapes and small penetrations...and..its not continuous, but side by side , a sample of kraft laminate facing will perform just as well as the poly...u and i agree on this, though, we'd both prefer unfaced, and we'd probably prefer cellulose..at least we're not stuck in our ways like that old guy, Joe Fusco..hah, hah, hahb but hey, whadda i know?
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OK, help me understand this:
When I built my house 2 years ago, I installed the insulation (kraft faced) with the kraft paper stapled to the face of the studs. When my drywall sub came in, he made me unstaple and re-staple to the inside surface of the studs because "the drywall adhesive won't stick to the paper". If I use poly on the next house, how in the world is the adhesive supposed to stick to the plastic???
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With screws.
Gabe
*adam.. yur a PITA... you need help... where do you live... we gotta get u some counseling...yur drywall contractor was absolutely right... you cant glue the drywall to the studs if the kraft is stapled to the face....you shdda fired his ass as soon as he said unstaplet the insul and staple it to the sides,,,what a bozo...(him, not u)..gabe is right if ther is no surface to glue to , obviously you don't use glue...you screw it up with no glue... like the majority of drywall installation...one component of the building system can't mess things up for the rest of the components..now some are gonna tell u not to use a vapor barrier at all... but that is missing the point..... there is no good reason to have to glue the drywall to the studs in addtion to screwing it...
*Mike,I'm pretty sure we do agree on the use of a kraft faced paper as a vapor barrier is bad new. BUT... I do believe you must have misunderstood what I was saying somewhere along the line. According to Owens-Corning and Certainteed (makers of insulation) kraft paper is a retarder, not a barrier. They also state that the vapor retarder is a one way ticket to allow moisture out of the structure, but not back in. It has to do with the way it is processed. This is not some fantasy that I dreamed up, it is what the manufacturers say about their product.Anyway, the paper should face the heated side of the room. If, as you said, it is reversed, moisture will build up on the insulation and create a mess. I repair homes, and the most significant problems I face and have to repair are moisture penetration problems. Moisture in the walls will destroy just about any material it gets wet (for long enough of a time). Most of the time, I find that the installation of the windows, doors, siding, etc... is a piss poor job from the start, and has allowed moisture to seep into the wall cavity where it wreaks havoc. In a lot of cases, the fiberglass insualtion will be quite wet (not quite soaking wet though) and the back side of the drywall will be bone dry. This, in my opinion, substantiates what the insulation manufacturers are saying - that the moisture vaprr passed through the kraft face into the wall or ceiling cavity, but doesn't come back.This is what I have to go on - what the manufacturers say, and my own experience in seeing it.I still say kraft face insulation is not the best way to go. JMHO...James DuHamel
*Jim... i do the same type work as you.. ..i think Certainteed used to do the same as all the insulation mfrs..they USED to call the kraft facing a vapor barrier.. then someone corrected them and told them it didn't meet the definition of a vapor barrier.. so they started calling it what it was .. a vapor retarder...most materials are not vapor barriers, except metals and glass.. most are really RETARDERS... (genel knows the perm rating for when one becomes the other).. anyways..some of the mfrs decided they wanted to develop house wrap and they specifically engineered their products so moisture would pass MORE easily one way than another...Tyvek is one of the few who actually succeeded..but, as far as i know , the kraft paper on Certainteed is the same as that on all the other mfrs.. and it is not appreciably different front or back.. its still a layer of kraft... a layer of cut asphalt and another layer of kraft.. it's just a sandwich.. and the difference in front and back don't amount to squat...the real problem they got is this.. if the vapor retarder is on the heated side of the house in most climates the moisture will try to get out of the high humidity side into the....cold low humidity outdoors (typical winter scenario).it will hit the vapor barrier and not penetrate and eventually be diffused within the structure.... if the vapor barrier is on the cold side.. the moisture will go thru the insulation and condense at the back of the vapor retarder... and it would do that even if they turned the kraft around...so, what i'm saying is that Certainteed doesn't have a front and back to the retarder ,, just a front and back to the insulation here's some perm ratings for matls: (PERM eance = 1 grain of moisture per sf. per hour)alum foil 0.0 (no grains of moisture will pass thru it)6 mil poly 0.06 perms4 mil poly 0.08 permskraft/asph. lam heavy 0.6 perms (10 x the perms of 6 mil poly)kraft/asph lam light 1.8 perms1/4 inch plywood w/ exterior glue 0.7 perms (about the same as the kraft/ asph. laminate)15 lb. asphalt felt 5.6 perms (excellent rain screen, but will NOT trap moisture..3/8 gypsum wallboard 50.0 perms (obviously a retarder, not a barrier)SO...., Certainteed MAY have a proprietary kraft laminate, but it's performance is still going to be similar to everyone elses...my source is Archt. Graphic Standards.. and it is old enuf that they don't talk about Vapor retarders.. just vapor barriers.. even though the numbers listed above make it plain that only metals are a barrier...the rest are just retarders...the discussion at this point in Arch.Graphic Standards is in NOT creating a building section that is going to retard moisture at a location inside the cavity which may be below the dew point...so, once again, you and i agree Jim, it just remains to be seen wether Certainteed allowed that into print without meaning to, and if they meant it.. why they arn't promoting this MIRACLE material they are using for kraft faced insulation...b but hey, whadda i know?
*Although I agree about the insulation, and about firing the drywall dude, in my area, none of the drywallers (there are seven), will do a job that does not have the stud edges exposed for gluing and screwing. I tried several times (and through several subs) to get this changed, but in our economy, they just say "see ya".
*Jason...i don't understand this ..it is contrary to the mfr's directions to staple to the side..and it's contrary to good energy conservation practise..on the other hand , i don't understand how GLUING the sheetrock got to be accepted or expected practise in your area....i would think the rockers wud be glad to eliminate an extra labor step, a messy application, and a material cost that isn't needed......i have only seen gluing sheetrock recommended if you are doing a two layer rock..where do you operate? where did the practise of gluing AND screwing come from?do they screw AND glue the ceilings too?what happens when someone uses unfaced fiberglass batts and a full poly vapor barrier?do they refuse to hang on that too? is it just that they can't see the stud? or is it that the glue won't stick..?something rotten in denmark hereb but hey, whadda i know?
*The problem here is simple--they're avoiding callbacks. They glue and then screw the drywall to the ceilings and walls, and then texture all ceilings (getting someone to do a good flat ceiling is next to impossible). The idea is, I'm thinking, that they hope that by glue and screw to the stud faces, it reduces the number of cracks from shifting and settling, and thereby reduces callbacks. I should also tell you that the economy is so strong here (Michigan), that they'll blow you off (even after a dozen houses), without so much as a bye-bye. And I see their point too, we end up culling about 20% of our lumber (and that's from the best place in town). For each house, I end up replacing probably 20 studs or so right before insulating because they warped, bowed, and twisted after installation. As for manufacutrer's instructions--I'll check the package next time, or I'll simply switch to one of the blow-in cellulose methods. I always, always, always like my way better (unfaced stuff in batts covered with a 6-mill poly retarder), but the only guy who did it for me is in jail now! And if you only knew the other things that I see on a daily basis which "are contrary" to manufacutrers instructions!
*Guys those crinkly, rinkled, kraft face edge tabs just make it too hard to get the rock tight to the studs when stapled to the face of framing members. Combine those doubled up edges with un-set staples and you have a job with loose rock. IMHO kraft face sucks for any wall insulation.Jason there are numerous condos and houses that i insulated in the Lansing MI metro area. What town are you working in? joe d
*so jason... joe d .. what do they do if you have unfaced batts and 6 mil poly?and... don't you use KD studs ? don't your framers sight each stud before they nail it in so it doesn't have to be uninstalled before insulating?if you're using KD studs, you shouldn't be getting this kind of movement...b but hey, whadda i know?
*Hi Mike S,Rockers screw rock around here. Rockers screw rock to poly covered framing.I use dry studs when i use wood. I have to shop to find them since everyone sells pond-dried stuff here. Since i cover them within a day or two the pond-dried stuff gaurantees nail-pops. Wood studs are ususally used by me for minor commercial remodels, i rarely work on houses now.I'm my framer and i check all material before installation. I both cull and crown studs, the straightest studs are used for kings & jacks.Over 20 years ago when i got my first construction job insulating buildings i was taught to staple kraft in between the members. I was also taught that kraft insulation without poly didn't have an effective vapor barrier. I always reavaluate what i think i know when it seems appropriate. If you think i'm missing something important here feel free to hit me over the head with a 2 x4 about it.Regards, joe d
*joe d..sounds good to me.. except yur not supposed to staple to the inside...automatically creates a half inch channel up each side of the bayhave you tried friction fit?.. the fibers are tighter,, there is actually less glass fibers blowing around in the air... the job is tighter and goes faster and better.. almost as good as celluloseb but hey , whadda i know?
*Mike, I used kiln-dried, but I get warps, twists, and cracks in the best of them after they're installed. Even after culling, I have problems that are not acceptable to me (although in many cases they are to the rest of the guys I work with). As for my area, I've worked in St. Johns, Lansing, Williamston, and the Upper Penninsula.
*Yes Mike i've always preferred friction fit. Safe to say that i've installed semi-truck loads of the stuff. Its kraft insulation that i try to avoid. Yes and semi-truck loads of cellulose too. Trust me i saw and installed more insulation than i should have.
*joe d.. . so what's your favorite?and do the rockers glue wher you are??do you use poly as a matter of course?we do 95% remodel... so a lot of our insulation is friction fit with a poly vapor barrier..when we get into addtions , it winds up about 50/50 between friction fit/poly and cellulosejason..on the addtions we cull from the stack to the cutting bench.. i prefer the hem-fir green for additions..and the KD for small remodeling,, start dry, stay dry, keep it dry.... but we still cull a lot.. we just try to cull before it gets nailed..haven't figgered why the mills use the worst lumber for their KD.. i'd rather get the hem-fir as KD..have you tried any of the engineered studs?..i haven't even seen any of them..
*My favorite?No glue, just screwpoly yesAnd now for studs. I've never forgotton when they sent Hem-Fir studs from the NW to a job in Okemos MI over 13 years ago. We thought they were unbelievably good. Course back then we were getting SPF out of the Canadian tiaga. Those studs were coming from old growth pecker poles or something.Then about 10 years ago i moved to OR and caught some of the last old growth Doug Fir studs. These studs are things of beauty and way too good to frame houses with. Of course they're gone now; you find a few every now and then. Here Hem-Fir is sneered at as dimensionally unstable, weak, and otherwise unsuited for framing. Now that's not quite fair but most NWterners have been here longer than me.I rarely touch insulation these days and that suits me fine.Now Mike i'm ready to abandon this thread for good, are you?joe d
*Hem Fir studs? You guys are crazy. We get SPF only, some joists graded as #1 that have knotholes so big I can stick my thumb through (and I have a rather large thumb that gets in the way every time I roof). The best studs I ever saw came from Classic Post and Beam out of Maine. I ordered up an extra pallet "just for scrap and bracing" with a timber-frame I put up. Every single one of them was clear. Nowadays, I'd plane them down for cabinets. Oh well. In my area, engineered studs really haven't caught on, but I do hear talk of them coming around the bend. As for drywall, I asked my guy today about that. He hemmed and hawed and said he do it (screw over poly sheeting without nails), but spent quite a bit of time trying to talk me out of it. I really have a good relationship with all these guys, so I'd like to switch to a blow in cellulose product of some type. Care to direct me to a site, article, or the correct forum guys? Appreciate it as always.
*jason... right church , wrong pew..go to Energy, Insulation & heating ... and punch up the thread (((Installing DP cellulose)))
*Mike, FYI, in my home area, northwest NJ, standard practice is (or was 4 years ago) kraft-faced FG stapled to the inside of the studs, no additional VB, and drywall glued and nailed or screwed to the studs. I'm not defending it, just reporting.Andy
*Andy....no accounting for anything is there ?here in RI, it's accepted by all the buiding inspectors that foam can be installed on the outside of foundations ..FROM THE GRADE LINE down....so , to comply with the energy code , that's how 90% of the foundations are insulated..the ground tempered areas get the insulation... and the concrete exposed to zero degrees get nada..b but hey , whadda i know?
*Interesting exchange in this months letters in JLC with Lstiburek responding to a poly guy. It includes some remarks on kraft faced fg and permeance. I only skimmed it but believe it said the permeance varied. Actually, it seem to make a strong case for for neither kraft nor poly, if not everywhere then in at least a good portion of the US.
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We have a little disagreement in our office, Is it required or do you need to install a vapor barrier over fraft faced insulation in new construction?