I’ve just started into a pretty enormous one-man insulation job, and the nit-wit (me) who built the structure apparently didn’t think it mattered that much to end up with stud bays that were all pretty uniformly 15 inches wide (16OC). SO … I’ve got a LOT of cutting to do! Working with R-21 fiberglass insulation batts … at least, thank god, it’s the white stuff with no formaldyhide and no smell!!!
I was just wondering if anyone here might know of any tricks of the trade with regard to cutting the batts to size? I’m using a simple pair of hand sissors and, though it can be done, it seems somehow inefficient and like there MUST be a better way!
Any ideas?
Thanks!
Aaron
Replies
Huh! With 16" on center you should have 14 1/2 "s between bays, standard batts should fit.
If you have to rip insulation, lay it paper side down,use straight edge to compress fiberglass and cut with razor knife.
Dfd you buy insulation for metal framing which I believe is 16"s wide. Don't quote me on that.
"Shawdow boxing the appoclipse and wandering the land"
Wier/Barlow
Edited 8/19/2009 11:45 pm ET by dedhed6b
Edited 8/19/2009 11:46 pm ET by dedhed6b
Get one of those unility/razor knives with the long snap off blades. Blades are maybe 3" extended. Make your cuts in a few passes to avoid tearing up the kraft paper face too much (if that is what you have). Always keep a sharp blade. Hold the bat up to the stud bay to get a visual on the required width and then lay it on the floor to cut. Cut on a wood surface - not on concrete.
I've used an electric bread knife, the one with the two blades running back and forth next to each other. It works really well and is fast for long rips.
Frank
I compress it using kneeling on a 2 X 6 as a straight edge. Use a cheap long thin butcher knife, keeping it sharp. Cuts like a hot knife going through butter. Don't forget to wear a respirator with a good seal. I feel this stuff is as dangerous as asbestos.
Virginbuild
Wow! Some GREAT ideas . . . gotta love the 'electric double bladed bread knife!' (Where do you get one a those!?) Knowing me, I'll likely end up using the paper sde down compression with board/straight-edge and razor approach. I'm doin this job myself . . . I'm not about to hire in insulators at thousands of dollars! The only thing I haven't done entirely by myself on this job is the foundation and now I've decided to try to find someone to do the drywall. That'll be it.
THANKS for all of the feedback. Much appreciated.
Aaron
I agree with Hudson Valley Carpenter. If you call around you'll likely find it CHEAPER to have an insulation company do the whole thing (materials and labor) than it will be for you to just buy the insulation.If you must do this job out of pride or stubbornness or whatever, I have had success with a straight edge to compress the FG as others have said but using a long roast beef type knife to cut it. The kind of blunt tipped knife you see chefs use when you're at a buffet and you come up to the huge hunk of meat usually under heat lamps and they'll slice off whatever you want.
It's nice to have a motorized grinder close by with a 60 or 80 grit wheel on it to occasionally give the knife a quick lick on each side. You don't want it finely honed on an 8000x water stone. The knife needs a bit of "tooth" on it to saw through the fibers.
"I'm not about to hire in insulators at thousands of dollars!"I don't understand this. why pay top dollar for the insulation and then install it for free when good insulation company can get it all done with better quality for the same cost as just you buying the insulation. Get pricing to have cellulose or BIBBs blown in and you'll be a happier, healthier man.
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I don't understand this. why pay top dollar for the insulation and then install it for free when good insulation company can get it all done with better quality for the same cost as just you buying the insulation. Get pricing to have cellulose or BIBBs blown in and you'll be a happier, healthier man.
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Piffin ---- I agree with you 110%. IF I had asked my question a while back I DEFINITELY would have gone the route suggested here. I had NO IDEA that it could actually cost only as much as the insulation to have the job totally done! Of COURSE if that is true than I missed an incredible opportunity to save time and trouble. I'm sorry for that but there's nothing I can do about it now. I've got all of the insulation here ... there's no returning it as I bought it over two years ago now when it was on sale .. they don't even carry this kind anymore at the HD that I got it at. So .. I've just gotta install it on my own! Believe me, if I could go back and do it again I would.
A~
Of course, by buying it two years ago on sale, you may have saved too by comparing to the cost installed today. I don't know that one. My insulation sub was out to peek at the job today before he sends his guys to start monday. His business has not been hurt in the least by slower economy. Cost of energy and the stimulus govt money / tax incentive has everyone and their heifer getting insulated to the max, so no discounts and sales going down really.Bibbs is Blown In Blanket insulation. Chopped fibreglass - white like cotton tufts. Maybe supposed to be BIBs
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You can't do this job as cheaply as you can have it done by professional insulators, even if you pay yourself ZERO per hour. They buy insulation at prices that no one else can touch. And their installer will make the insulation fit perfectly, very tight. He'll be done in one day.
Call a couple of insulation companies before you put yourself through any more of this kind of misery.
Edited 8/20/2009 5:00 am by Hudson Valley Carpenter
I think I told him that a few weeks ago. I think he has something to prove - even if it takes him 10 years.... Whatever floats his boat.
I also use a boning knife and a 2x6; always cutting paper side up.
Use the words on the paper to insure the batt isn't kinked or bunched under the straight edge.
I cut on a sheet of OSB to keep my knife sharp and out of subfloor joints.
Keep a sharpening stone handy and you will be happy.
Scissors are good for cutting around outlets.
Get a good respirator or cough for a few days.
Gloves and safety glasses a must too.
A good hammer tacker is much less frustrating
Don't keep boxes of staples in your pocket.
DC
+1 for farming it out.
Insulation and cement - neither are good DIY projects 'cause the guys who do it all day will do it faster, cheaper AND better than you can.
Also, you may wanna consider blown-in cels instead of FG batts.
Mike Hennessy
Pittsburgh, PA
Everything fits, until you put glue on it.
I bought this insulation .. a HUGE load of it .. nearly two years ago when it was drastically on sale at one of the big box's. It's been piled to the ceiling off to the side for all that time .. now I'm beginning to drop that mountain down .. down ...
If I had asked about it earlier and it was acutally true that pro's could do the job better AND cheaper than my just buying the stuff myself BELEIVE ME I woud DEFINITELY have looked into it. But now I've got the ground floor pretty much done (including quite a job of coming up with a way of fitting R-30 into a 9 1/2 " ceiling! WITH 2 inches of airflow space above) and I've pretty much got the 4th floor done. So .. I hear ya and WOULD have strongly considered goin that route had I asked about it earlier but now I've got the third and second floors to do and all of the insulation here so it just doesn't seem to make sense now. But the drywall .. now THAT is something I"m intent on farming out. Just hoping it isn't too prohibitively expensive!
Thanks to all who responded helpfully -
A~
Ditto the butcher knife.
I wonder how much extra the drywall will be with the framing not on 16" centers?
Just wonderin.
I wonder how much extra the drywall will be with the framing not on 16" centers?
Shouldn't matter if the framing is otherwise done correctly. Most residential drywall is hung horizontally, using 12' boards, sometimes longer.
Heck, drywall is where a lot of money i s in the labor. Just think about how much you could save there!;)
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What you said.
If'n I was the OP, I'd sell the FG on Craigslist or whatever and go pay a contractor to blow cellulose in. I hate installing insulation.
One thing I'll add to protection of skin--rub in lots of talcum powder on forearms and neck. The powder does seem to keep the fibers of the fiberglass from getting into my skin so much, though it still gets itchy, but not as bad as usual. I also wear a mask and gloves and glasses--goggles would probably be better, but my glasses get fogged up enough as is. Mask with exhale valve is also better to prevent fogging of glasses.
Get yourself a heavy (3/16" +) strip of aluminum for a straightedge - compress as described.
Okay, I have read all of the responses so far and I will attempt to add a few more tips. The posters are correct in that an insulation company can install it for much less. I buy an semi load (20k) at once and when you see the price you then know how Lowes and HD are getting rich! But since you have already bought your insulation we wil go from there.
I have installed thousands of bags of fiberglass insulation so I feel qualified to comment. I take it that you are installing Johns Manville insulation. If so you are in luck. There is practically no itch with this insulation. I do recommend using a mask while installing (N95 approved). For me gloves were never necessary and mostly a hinderence. In reality wearing safety glasses is a good idea, But you will sweat so much you will never be able to see. I think I can recall getting insulation in my eye once in 10 years. Some people like to wear long sleeves to keep from itching, but if you are using JM, unless you have sensitive skin, you should not have an itching problem.
When cutting batts always cut with the paper facing the floor so you cut through the paper last. I have always used a plain utillity knife with sharp blades. Get you some Irwin blades. They seem to be much sharper and will hold their edge much longer. Frequently change your blades. Usually I will use about 5 blades on an average house. Cutting on concrete will dull your blade very quickly. Avoid this if at all possible. Forget compresing the batts and a straight edge. R-22 batts are already highly compressed and do not have much "fluff" to start with. I will usually cut my batts about 3/4 of an inch wider than the stud bay. With a little practice you eye becomes as good as a straight edge and using a straight edge would take forever. Professional installers do not use straight edges or shears or any of these other fancy cutting tools, just a good eye and a sharp utility knife.
Use a slap stapler and not one of those that you have to squeeze. You can get a good slap stapler at Lowes for 20.00. Make sure to have a puttty knife about three inches wide to stuff loose insulation around windows and doors. Lightly pack it other wise the jambs will get compressed.
If you want a really good job get some great stuff foam and spray a touch behind the receptacle boxes on the outside walls. When you have a stud bay with a receptacle box in it first put the batt in at the top of the bay and smooth it down about half way and then staple it half way down. Make to staple into the sides of the studs and not to the faces. The drywallers will thank you. let the batt hang over the receptacle box and cut through the batt at the top and bottom edge of the box. do not cut the side. Then just fold this cut piece and slip it to the side of the box. This is much faster than cutting it out completely.
Hey! Thanks for this!
You are absolutely right .. .it is Johns Mansville batts. I am glad I got it because it was heavily on sale and it is white and fluffy and scent free almost like it is pure cotton. Sometimes the yellow stuff smells so bad it gives me a headache .. but not this stuff. And you're right again, I do feel I need to wear a mask .. but I only use a surgical mask, nothing more, and I wear loose goggles but don't really feel much of a need for any more protection than that. The stuff is great to work with, plain and simple. No itch, no fuss.
I am really finding it hard to believe that this whole job would of been done for only the price of the insulation! But .. maybe so!
Thanks again ... some GREAT feedback that will help me out for sure.
Aaron
I am really finding it hard to believe that this whole job would of been done for only the price of the insulation! But .. maybe so!
Nobody wants to believe that they out smarted themselves by not doing enough research before making a decision.
A great deal of money is made in this country by people who figure out how to buy products at a better price than the competion, then resell them slightly below the market price.
That's the case with fiberglass insulation and the retail market vs. the wholesale market. Granted, it is a peculiar segment of the construction industry but nonetheless, what we're all telling you is true.
You can still get the job done, labor and materials, for less than the price of the insulation...if you're willing to regroup, sell the insulation you have on Craig's list, then hire a big insulation contractor to do the job.
Zup to you buckeroo. But there isn't anything to be gained from doing this job yourself.
"I am really finding it hard to believe that this whole job would of been done for only the price of the insulation! But .. maybe so! "I am reading this and thinking of the many thousands of square feet of insulation I have installed. I installed it mostly for my previous employers; but now I install it for myself. I don't mind doing it - I sorta enjoy it - and being that most of my jobs are small remodels (under 1000sf of insulation) I never figured it would be worth hiring it out. Now I am wondering....how much does it cost to hire out?What size project makes it worth it?Being a remodeler, I do pretty much everything myself.... are there any other tasks that I should be hiring out?I don't mind the work (except when it comes to roofing and painting, i hate those jobs) but I am all for saving time and money. BTW: I staple the walls on the edge and the ceiling on the sides so I can glue to the joists.DC
DC,
Now I am wondering....how much does it cost to hire out?
What size project makes it worth it?
Being a remodeler, I do pretty much everything myself.... are there any other tasks that I should be hiring out?
Great questions for a new thread.
I like to sub out insulation and drywall. Unless its a too-small remodel.
Jim x 3
You saying you sub out drywall hanging AND taping?Again, with the small jobs that do, I usually hang and tape.When the client is already see-sawing on my price; I couldn't imagine making a living while sub-ing out the work.I guess I would more seriously think about it on jobs above 1500sf (approx 24'x24'x8') of ins/rock/mud. And while I will indeed look into the next time such a job comes along, I still take pride/pleasure in being able to remod spaces of that size and smaller solo.I recently tried my hand at foundation/block work... I think I'd rather hire that out.I hire out most flatwork too.DC
being that most of my jobs are small remodels (under 1000sf of insulation) I never figured it would be worth hiring it out.
Just an educated guess but that's probably about the break even point for insulation contractors. However, their guys are solo subs who move around a lot, day to day so it may be that, in your area in the current economy, the minimum job size has gone down to a smaller number.
Worth making some calls, I'd say.
Thanks HVC, although I don't have any jobs going right now that are in need of it, I think I will start looking around for the next job. I assume you guys are saying I can only save money on insulation by going with a large insul. firm as they have the buying power, right?I just met a guy on a project the other day who tapes well and must be cheap as the same clients think I'm too expensive.DC
I assume you guys are saying I can only save money on insulation by going with a large insul. firm as they have the buying power, right?
My assumption is that anyone who puts an ad in the yellow pages under insulation is able to buy in quantity at the kind of discount which makes them competitive with others who advertise in that space. In any case, you'll never know what's out there until you get on the horn.
agreed all and very good stuff there.I was surprised how many guys are trying to compress with a strtedge!I use a regular $2.59 ute knife and definitely dittoes on the Irwin blades. I hold the knife near the end so it approaches the cutt at a long angle and the knife does the compressing as it slides the cut to the blade. For guide, I often hold my pinkie off to the side as a reference, maintaining the same crook or extend to it the whole length of cut.Just yesterday, I foamed my windows on this job and behind the recepticles getting ready for the BIBBs guys coming out.Having the wires neatly stapled in the right places makes for an easier insulation job too.
With that horizontal wire running about 18" above the floor, some guys slice the insulation halfway at that point. I just divide it in half to pull two leaves apart for that 20" or so, and tuck out out and one inside of the wire.Now for the eeeternal argument - do you fit the kraft flaps over the face of the studs or fit it inside?I staple faces when using kraft. But most often I am using foam or BIBBs
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sorry .. unfamiliar with the terminology .. what are BIBBs?
when I google bibb I get this:
http://moviesmedia.ign.com/movies/image/article/779/779725/talladega-nights-the-ballad-of-ricky-bobby-20060804060738880_1176308477.jpg
I would have to disagree with " Make to staple into the sides of the studs and not to the faces."The manufactures instructions, the architect's specs. the Veterans and HUD Admin specs, and EEBA literature prefer the staples neatly thru the paper flap into the 1-1/2" edge of the stud. If stapled to the side it leaves a convection channel from floor to top plate.In this case the OP will have cut off one of the staple folds, so it will nee tod be a friction fit on one side. So the comment about cutting 3/4" wider than the bay is good. Do not compress the bat into the stud bay.Before installing the FG...Caulk or foam all penetrations, wiring & plumbing holes thru plates or studs. Install metal "nail protection plates" over mechanical and electrical penetrations are within 1-1/4" of face of the stud.Take your time, be neat and precise, seal your houses insulation envelope to keep those energy $$$$ in the house and your wallet. The devil is in the details! In past issues of FHB there should have been articles on FG installation.FWIW.........Iron Helix
I missed that side of stud comment from Griff...He wants to get along with the drywallers, but I want the insulation done right. Side stapling also reduces effectiveness of any VB the Kraft face provides. Truth be told, I'd rather use unfaced.
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Okay - - - Here's one for y'all: in a quite large room off to the side of the grnd floor of the tower I'm building the walls are all built 10 ft. high out of 2X8's. The insulation I'm using is R-21 and it is 5 1/2" thick for probable use in 2x6's. So ... two choices .. set the batting back against the inside of the outer sheathing? OR .. staple it to the front edge of the studs. First way leaves a gap in the front between the drywall and the insulation . . . second way leaves a gap at the back .. at the cold side .. between batting and outside sheathing.
Is there a "better choice" of these two???
A~
Both ways would be a total waste of time and insulation. To be effective at all, fg needs to completely fill the stud cavity.
Both ways would be a total waste of time and insulation. To be effective at all, fg needs to completely fill the stud cavity.
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Huh. Inspector didn't mention a thing about it. No one else that I've run that question by has either.
Sorry, but if you are proposing to put R-21 in a 2x8 wall and the inspector doesn't say anything, he is incompetent.
To be effective at all, fg needs to completely fill the stud cavity
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So . . . every single stud bay that has any unfilled space in it at all is utterly useless? Lets heat flow on out through the walls just as easily as a house with no insulation at all?
When heat in the room I'm insulating passes through the drywall it will cross an inch or two of air-space and run into 5 1/2 inches of insulation between it and the outside wall; no way over, under, or around it. How could this insulation end up having 'no effect' whatsoever.
Let me rephrase that. For "optimal" effectiveness, fg needs to completely fill the stud cavity.Certainly, some insulation is better than none. But if one is going to the bother to do it at all, I'd think it would be best to do it in accordance with best industy practices.
Since he already has it in - to the outer face with sides stapled, his best bet would be to get 1-1/2" foam EPS to rip to fit each stud space to fill what is left
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84 Lumber sells fiberglass batts for the exact same price installed or carry out. I get off on kicking dead horses...It's not too late, it's never too late.
Since he already has it in - to the outer face with sides stapled, his best bet would be to get 1-1/2" foam EPS to rip to fit each stud space to fill what is left
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This has only been done in the walls of one of the five rooms I'm dealing with. If I were to 'take measures' relative to the situation at this point I was thinking I might go ahead and simply fill it out with fg 'padding' of a couple of inches thick. I don't know whether the fact that this would result in fg/kraft paper/fg would be a problem or not! I am a perfectionist (one of my primary failings) and did a bangup job on this. In looking around at the room it REALLY looks 'perfect'. Hard to believe that it would not hold the heat as well as if the studs were 2x6! It certainly 'appears' to be a fully insulated room!
>> If I were to 'take measures' relative to the situation at this point I was thinking I might go ahead and simply fill it out with fg 'padding' of a couple of inches thick. << You don't want a double vapor barrier though. You could just go get some R-11 FG and strip off the VB.
Might wanna just leave as is and call it a learning experience. As long as the FG is installed perfectly with no edge or end air leaks (including around outlets and whatever) it will be fine. FG was installed with a gap between the VB and the sheetrock for +- a half century so it isn't gonna effect world peace. It is only been within the last 10 or 20 years that the building science guys figured out this no air space in the stud cavity. An anonymous check with your BI may not be a bad idea though.
BTW - I'm sure you said it in another thread, but why did you use 2x8 studs?
You don't want a double vapor barrier though. You could just go get some R-11 FG and strip off the VB.
this is exactly what I was thinking. It's on sale for remarkably cheap right now. But what about that fact that there will be this odd sandwich of drywall/fg/vb/fg/sheathing? Almost wonder if I should mount the new stuff (if I actually do this) stapling the vb as usual to the outside edges of the studs and making sure to cut open the 'original' vb that will now be buried a couple of inches inside(?)
...so it isn't gonna effect world peace.
this had been one of my formost concerns in this situation, so I thank you for addressing it. If it WAS going to, I'd a probably just held off.
I'm sure you said it in another thread, but why did you use 2x8 studs?
this is a pretty big room .. 15x20 with 10 ft. ceilings... and at the point that I built it there was still a chance that it was going to eventually be extended to fill out the back of the lot creating a 15x40 foot 'Hall'. Still 'could' actually. I wanted the option of insulating it heavily against outside sound as it sits up against the property line on one side with a little backyard (neighbor) parking area literally one foot away. It turns out that's really not much of an issue, but I didn't know at the time. Also, that parking area has cars pulling up nose-first to the other side of the wall of my studio, and, I know this sounds crazy, but I had this dreadful thought "what if someday someone loses control of their car and comes sailing right into/through that wall? Would there be strength enough in a wall of 2x6's to stop it?" (This was shortly after my mother hit the throttle instead of the break and drove straight into a Chinese restaurant from the parking lot. Really.)Mostly though, I'd say it was because I'm not a pro builder, it was the first thing I did in the project and I had a sort of naive idea that bigger and stronger is better... especially if I ended up turning it into a really big Hall for meeting and gathering. Guess that's it. :)
Thanks -
Aaron
>> Almost wonder if I should mount the new stuff (if I actually do this) stapling the vb as usual to the outside edges of the studs and making sure to cut open the 'original' vb that will now be buried a couple of inches inside(?) <<
That would work. Half dozen or so quick slashes with a sharp razor would Do the quickly.
Again though, I wouldn't worry about it too much either way. In building we strive for everything to come out perfect but things happen. Even experienced builders (including me) make mistakes. It is the old adage - The only one who doesn't make mistakes is the one who does nothing. To add to that I've learned that the more responsibility one has, the bigger the mistakes...
I appreciate your assurances, but I want it to be done right and I want the room to retain heat well. If you hadn't described the situation so well here:
Think of this scenario: You have a stud cavity with a FG batt with the corner not firmly seating properly on the stud bay corner. The leak is 1 square inch in surface area. This means that there is a 1 sq in cold spot (during the winter) on the back of the sheetrock. Right??? Well, maybe. If the stud bay isn't filled the rest of the way with FG, say there is a 1"gap between the face of the FG batt and the sheetrock, then your 1 sq in leak supplies cold air to the back of the sheetrock in that entire stud bay - 14.5"x93" (or whatever size the stud bay is. Hope that made sense - a little hard to describe.
I might have been able to let it go. Now .. it's workin away on me. So .. I've now decided to finish building my two inside flights of stairs before proceding with the isulation so I've got a little time to kick it around. IF, btw, I DO elect to fill the gap out to the front of the stud wall .. would you recommend actually going ahead and slashing the vb? Preferable to just leaving it as a second vb?
Thanks (for ruining my peace of mind!)
Aaron
If you have 2 vapor barriers moisture could get trapped between and cause mold. Here, in NC it has gotten to where we are so paranoid about mold sometimes we don't install any vapor barriers in walls and never in ceilings.
gotcha . . . thanks!
".. would you recommend actually going ahead and slashing the vb? Preferable to just leaving it as a second vb?"Slashing the inside vapor retarder won't have much effect unless you really slash it a lot, opening up a lot of area to diffusion. Movement of water vapor by diffusion is proportional to area, and a few slits left with their edges fairly close together doesn't open up much area. The only way slits would help would be if air were flowing through them, and then you'd have a serious problem in that wall with convective air flow. The insulation needs to provide dead air to be effective.
good points . . . thanks.
Final point (i think!) ... in looking at the situation it now appears to me that the proper way to go with fg batts that were thinner than the stud bay cavities would've been to pull the batts all the way out to the front. In terms of everything we've said here I think this is true. If there is a sheet of cold at the BACK of the bay next to the sheething .. no biggie .. just like the outside air temp but dry. Then, there is still the R-21 'blanket' of fg all the way up to the vb which rests against the back side of the drywall. THIS would be the proper way to do it. No worry about some little quarter sized hole somewhere in the batting; if the batting is AGAINST the vb/drywall then even a little space or hole in it will be confined only to that one tiny spot.
So .. at THIS point .. IF I'm going to do anything about changing it now the effective thing to do, or it would seem so to me, would be to pop the staples, pull it all out to the front of the bay and face-staple it to the front edge of the studs. If I wanted to go all the way I could pull it comPLETEly out and slide some R-11 in behind it to the back. It would compress some ..but .. better than space it would seem to me.
Thanks -
Aaron
I'm no famn of FG bats, but I can't understand that statement.
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I would install the insulaton all the way against the sheeting. The reason is that you can then slide the insulation behind the receptacle boxes so you don't have to do any cutting and it will help preserve the thermal envelope. Of course some will argue thta you then cannot staple to the face of the stud.
Unless things have very recently changed the directions on most bags of insulation even say that it can be done both ways. Owens corning is even advertising an insulation batt that you do not have to staple even though it looks to me as being the same as all of the rest. If one is really concerned about the integrity of the vapor barrier, using unfaced insulation with a 6 mil plastic sheeting cover is a better way. I have quietly viewed the raging arguements over insulation types and methods here for many years. I would place fiberglass at the bottom of the list. But it has it's place in that it is much less expensive than most other forms of insulation. Closed cell foam is an outstanding product and it would certainly be my choice if price were no issue. But foam costs almost 3 times what fiberglass does. In my part of the country I feel that saving 400.00 a year on heating and cooling costs would be about the max savings on using foam over fiberglass. So if a man has to spend 6-7k to get foam, how long will it take to pay back? 15 years? I looked into being a Corobond dealer a few years back. It would cost me about 100k to get set up. I just feel that there are not that many people around here willing to shell out the extra when it can be spent on kitchen cabinets instead.
BIBS is short for blown in blanket insulation. With BIBS a netting is put up across the studs and a hole is cut in each stud bay and a hose is inserted and insulaton is blown into the cavity.
thanks.
this is the way I did it. batting to the back of the stud pocket. it leaves about an inch+three-quarters towards the front. debating whether to fill that in or drywall over. I now think that, given the choice, I would do batts to the front with gap at the back. But it sounds like, according to some here, either way is a bust anyway!
I have R-30 in the ceiling above so any heat passing IN to the wall that would rise hits that, which overlaps out over wall by several inches.
Yes. Fit to the outer sheathing and staple to the studs sides. This is a place where foil faced would be effective, BTW instead of Kraft.to understand some of the criticisms about FG and various methods, you have to understand the concept of a convection loop, but since you are in a fairly moderate climate, it is less important to you. If you really want more, say so, but I am almost all typed out tonight.
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to understand some of the criticisms about FG and various methods, you have to understand the concept of a convection loop, but since you are in a fairly moderate climate, it is less important to you. If you really want more, say so
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Well, I'm ok not to understand it all completely. Just tryin to get this damn thing DONE. Helluva thing for someone to say, "all of the insulating you've just done is utterly useless". Anyway . . . on with the show.
thanks -
Henry is right - "To be effective at all, fg needs to completely fill the stud cavity". The idea is you don't want to create areas for air to circulate around in within the wall assembly. This has been documented using inferred cameras that photograph temperature differences.
In building Energy Star homes the ES inspectors require (demand) this filling of the stud cavities. This means that for kraft faced insulation they want it face stapled. Or for unfaced fiberglass the material is just installed with the material face flush with the stud faces.
Think of this scenario: You have a stud cavity with a FG batt with the corner not firmly seating properly on the stud bay corner. The leak is 1 square inch in surface area. This means that there is a 1 sq in cold spot (during the winter) on the back of the sheetrock. Right??? Well, maybe. If the stud bay isn't filled the rest of the way with FG, say there is a 1"gap between the face of the FG batt and the sheetrock, then your 1 sq in leak supplies cold air to the back of the sheetrock in that entire stud bay - 14.5"x93" (or whatever size the stud bay is. Hope that made sense - a little hard to describe.
The guy I worked with doing remodeling always had me (I generally did the insulation, as he insisted that working with it made him sick to his stomach--I think it was psychological, or a way to get out of nasty jobs, but....) staple the flanges to the sides of the stud--that way he could run a bead of glue on the edge of the studs in the field of the drywall and then he would only screw the edges of the drywall sheets. He always installed drywall vertically.
Passe' building methods that have become "habits", are very hard to break. Energy costs should drive the wheels of knowledge.
But "i've always done it that way and never a callback." seems to be all too common!"The ultimate cost of that habit robs the owner(s) for the rest of the buildings life.What a shame and waste.............Iron Helix
Sounds like he did a lot of things wrong.
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I bevel a 45% cut along the length of a couple of straight 2x4's, then attach them with a cross-member (a small scrap of plywood) at each end so the bevelled edges are almost but not quite touching each other. Then I set that on the batt (paper side up), and compress the batt over a piece of osb or plywood, while I cut with a utility knife.
Some of the batts come perforated too, so you can tear a straight line lengthwise.
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Edited 8/21/2009 3:08 am by Huck
I bevel a 45% cut along the length of a couple of straight 2x4's, then attach them with a cross-member (a small scrap of plywood) at each end so the bevelled edges are almost but not quite touching each other. Then I set that on the batt (paper side up), and compress the batt over a piece of osb or plywood, while I cut with a utility knife.
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this is a GREAT and inventive approach! Sounds egg-sackly like the kind of thing I always end up coming up with. 'necessity is the mother of invention'.
Electric carving knife. Works on FG and the other stuff as well. I have cut hundreds of sq ft of the stuff. Easier than a turkey!