I pulled the luan paneling (1964 stamped on the back) off the basement wall to see what insulation was in there. There are very poorly installed 2″ paper faced batts installed in a 2×4 wall, with about a 1″ gap from the wall to the concrete. None of the batts seem to have been cut from their 14 1/2″ width, regardless of how small the stud opening was (some only 10″). They were also squished behind the fire stops. Is there any reason I can’t double them up and reuse them? I’ll need to pierce the paper on the exterior layer but the batts seem in good shape otherwise. How much space should be left between the concrete and the insulation? As a side note, I was surprised to see a poly vapor barrier. Anyone know when poly started being used?
Thanks,
Adam
Replies
>>any reason I can't double them up and reuse them?<<
Poor performance.
The few I pulled out still seem to have their loft. If anything they seem to be more than the 2" printed on them. How much performance could I lose? I have a hard time believing it would be enough to offset the cost of all new batts. Seems a waste to just scrap them.Adam
Poor performance ????? you are kidding right? What does that mean? He certainly will gain 'performance' over the single 2" batts.
No, I'm not kidding. I will not use fiberglass for anything anymore. It's just an inferior product that does not perform well, deteriorates over time, has trouble with moisture management, creates difficulty in air sealing, allows for convective heat loss, and is probably carcinogenic.I remove and landfill just about any FG I have to deal with and replace with cellulose most of the time, sometimes foam.And yes, doubling up the 2" batts will probably perform better the the singel 2" batts, but that's not saying much.Steve
Hey, using other insulations is your choice and well respected. In my opinion, if installed like it is supposed to be installed, it will give you the R-value that it is tested at. I've seen these guys selling cellulose packing around a demo box showing how air forced through two insulations (FG and cellulose) moves much more freely through FG. While that is all fine and dandy, most installs generally don't have a hole in one end of the wall and another in the other end and a fan hooked up forcing unconditioned outside air through it. The demo illustrates a very good point, but most of the time the hard sell makes it sound like if you don't buy the product, your house will be like the demo box and that simply isn't the case.
I'm all for good products and paying for what you get, but I tend to detest hard sells designed like midway tricks to get you to buy.
I respect your choice ... very much so. I even commend your committment to higher quality products. There are people out there that would say that anyone who does less than foam is being cheap. In my book, you pay your money and you take your choice. In the insulation business, you tend to get what you pay for IMO. Better insulation pays in the long run, but we all have to balance the long run w/ the first cost.
Having the staunch attitude that you landfill all FG that you run into really goes against the environmental grain of saving energy and resources in the first place. There is a time and place for everything and i don't think we should landfill useful materials just because we feel strongly about something else.
You don't have to rip open very many
houses with fiberglass to see the reality of air movement. The typical home is full of air leaks Electrical runs,
plumbing, light fixtures, drywall joints,normal framing,
windows, doors, mice holes,etc. Very common to see mold blooms and or dirt deposits emanating
from these holes. Plane as day. So, "sales pitch" aside FG does not often achieve anything like
it's purported effectiveness. All this is assuming we are talking about bats of course.
I absolutely agree. The primary reason is poor installation. Installed PROPERLY, FG should perform fairly well in an enclosed cavity. It's R-value is good IF installed right. As far as air leakage, it isn't really designed for that. Dense pack cellulose has it down for that ... but if the cavity is otherwise 'tight' there is no reason that FG won't be as good as cellulose R-value for R-value.
A primary reason cellulose is pushed so much (and rightly so) is that the same skilled tradesmen can do a MUCH better job w/out additional skills or the attention to detail. That is part of the problem these days ... tradesmen who don't pay attention to details. Quite frankly I like cellulose, but I also believe in truly informed decisions ... knowing all the facts.
>>if the cavity is otherwise 'tight'...<<Therein lies the rub.
I know ... you're right. But the cavity isn't as loose as the cellulose demo machine that literally has large holes in each end and a fan forcing air through the two samples. A reasonably built wall will have reasonably 'tight' cells. Then you can do like some have done and caulk the seams of the sheathing. ... but that brings us back to even more labor .... which is likely offset by the higher cost of cellulose.
Again ... pay your money ...
I agree with you that well-fit FG in an airtight six-sided closed cavity will insulate just fine. But I've yet to come across an airtight six-sided cavity in any of the construction I've opened up. Even in relatively contemporary framing with plywood sheathing and sheetrock on the inside. I've torn into a lot of walls and have yet to find FG that was performing well. Even when the batts are still lofted, I almost always find that the cavities exhibit a lot of evidence of air movement...black streaking of dirt throughout the cavity indicating air movement, and usually lots of mildew staining. The attached picture is pretty typical.When it comes to older houses with irregular framing, board sheathing, or no sheathing at all, the FG I've taken out has been completely worthless. It's usually been nesting critters for decades. Many, many rodent and bird skeletons. Usually the FG is in shards, slumped, compressed, crumbling.I'm all for green re-use. Restoration is what I do. The greenest house is one that already exists. But I think FG insulation is one of those legacy building traditions that is best abandoned. No amount of savings in initial cost can make up for its performance and durability problems, IMHO.Steve
I hear what your saying. I've pulled out some more insulation and a lot of it's in really good shape. I think there are enough other big leaks, that not much was being pulled through the insulation. Knowing I will be using batts regardless, I think I'll re-use the good looking ones and chuck the others in the garage attic or trash.Here a couple photos of the batts.
I just hate to see people waste the opportunity to do it better when the walls are open.Steve
I agree doing the best you can when the opportunity presents itself. It will be much better than what it was. I just don't have the tools to dense pack cellulose and I'm doing a bit at at time so, spray foam is not a great option. If the whole basement was a blank slate, it would be another story. I will do all I can to limit air flow and seal things, but for this round, FG is what will go in the walls. Thanks for the feedback.
In my case, insulating a wall next to the concrete foundation, how do you leave any breathing room behind the insulation with cellulose? I plan to use fiberglass. Whether I re-use or not is the question. I'll blow cellulose in the attic, but the basement walls are a different story. If I can believe the manufacture's numbers, materials cost for cellulose is actually cheaper here. For 1000 sq ft of R20, cellulose= $365 + $35/day blower rental FG=$693
how do you leave any breathing room behind the insulation with cellulose>>>>>>>>>>>>>>>>
Is this really necessary??
I don't really know if it's necessary. I've always thought you should not have the fiberglass and studs pressed tight to the concrete. I can't say where that idea comes from. Could have been from helping my dad insulate his basement when I was in my teens, 20 years ago.That may not be the case and maybe isn't at all with cellulose. The foundation is not dead straight and smooth. The gap behind the studs is from about 1/2 to 1 1/2".
As long as it is not damp I would use the cells.
finehomebuilding.com articles and best-practices from buildingscience.com say that you don't. You put rigid foam insulation against that concrete wall. Wood studs filled with batts against or even near the bare concrete wall are inviting moisture problems.You seal the foam tight up against the foundation walls. You can then fill the stud cavities with FG batts if you desire but it appears most don't, they just use 2" XPS rigid foam against the wall.
Getting foam behind the studs would mean cutting out the wall, trimming ceiling and moving it forward. In some places the studs are awful close to the wall. All I intended to do when I started was replace the paneling with drywall, add some insulation and fix the vapor barrier. Calgary's a pretty dry climate and I've seen no evidence of moisture problems from the last 30 or 40 years of the batts being in there. Granted, the vapor barrier was full of holes, so maybe the wall breathed more than it will when I'm done. Only a few of the nails holding the baseboards on were a bit rusty.So easy to create new problems, fixing the drafts and air leaks in these older homes.Adam
If no problems in 30-40 years, then, reuse the vapor barrier. Dry, absolutely I lived in Saskatchewan for a few years. I am still haunted by the memories of the winter there :)
People look at me funny when I say I had a de-humidifier in Montreal.
Never heard of one of those. The vapor barrier is shot, I'll put up new poly and seal with acoustical sealant to minimize air movement.
insulating a wall next to the concrete foundation, how do you leave any breathing room behind the insulation with cellulose
If you really wanted to, put insulmesh on the backs of the studs. The studs shouldn't be in close contact to the concrete walls anyway.
Best bet would probably be spray foam behind the stud walls, with no wood contact on the concrete.
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
But rodents love it.
Wonder why they aren't all lying dead in the walls with FG lung disease?
Tearing down a building on some land I bought, FG chewed into nests filled with rodent poop is what it has for insulation. Disgusting ain't even close.
Joe H
As long as the batts have plenty of loft to them, you could reuse them. It's not the FG that insulates, it's the still air that they hold.
And, as you've pointed out, proper fitting is essential. The previous installer obviously thought that by cramming a 14.5" batt into a 10" space was a good thing. It's not.
Scott.
We just moved in to the house a couple months ago and I keep finding all kinds of interesting things. I haven't pulled down all the paneling yet but I'm sure I'll find more surprises.
I've thought of this many times, as your situation isn't very different from mine.
I've decided to replace the batts as opportunity presents itself.
Why? Because they just don't seen to have the 'spongeness' or firmness of new batts; because many contain a fair amount of dust, or have signs of insect / mouse visits, or were more exposed to weather than they shuold have been dut to leaky walls. In short, I don't think they're up to current standards, so I'll replace them. Doing so will give me peace of mind, if nothing else.
The act of removing the old ones - apart from the obnoxious dust that gets put in the air - also exposes all manner of defects and faults that have lain concealed all these years. You can see the places where air leaks or water enters. You can get rid of all the tracs hidden there years ago. It's a good chance to map out wires and super-insulate pipes.
There remains the question of what to do with the old batts. Maybe others have found a use for them - I sure haven't.
My other option for re-use would be to fill the stud cavities in the detached garage, that is slowly transforming to workshop. The studs are 24"OC though, so the narrower batts would be a pain. Eventually I'll get a heat source in there.Adam
That's a very good idea. Even if the insulation value is nil, they'll really cut down on the noise!
If you use in the garage, set up a cutting station and cut 24" batts (or e.g. 22 1/2" batts) and place them sideways ... stacking them up. No longer 'a pain'.
Don't dust mites and bugs have an R-value around 4.2 per inch ;) I think ASHRAE lists them in their insulation tables ;).
Good points, but tearing out will spread dust and mites and leaving them in isn't much different than what he might see in a couple of years in the wall anyway. Pay your money, take your choice.
I've chucked them in the attic. They won't add any R-vaue, but it don't do any harm either.
Absolutely. Don't toss them. W/ 2-2" batts in a 3 1/2" wall you lose a little total R-value, but it's better having them used than toss them. The cost is right on and the minimal loss of R-value (over the doubled insulation value) will be small. Go for it.