Attic insulation: do attic floor, or roof, or what? And, how much work (ie $$$)?

Am a bit confused about how one does insulation in the attic. I read here that for some attics, you insulate the roof, and for other types, you do the floor.
Something to do with whether or not it's vented, I think.
Our house, 2-story (storey?), roughly 1940 or 35, has, we believe, very little insulation.
I've heard that if the attic is all buttoned up, no air from the outside flowing through, in THAT case one insulates the roof -- between the rafters.
And, if there is flow, eg via soffits, then you do the floor.
Is that true? and WHY the "rule"
Our attic has NO soffits -- but it does have an attic fan, maybe a yard in diameter (the circle made by the blades), with louvers to the outside (fan blowing air out opens the louvers).
Now, I had mentioned to a self-employed light-construction guy that I was interested in maybe insulating the house (at THAT time oil was 100 a barrel or so!)
And he said his brother did insulation.
So, just 30 minutes ago, unannounced, they rang the doorbell.
The brother went up into the attic (roughly 15 by 8 yards in area, via my stepping it off), and came down and said he could do it for $12,000. (I had seen a show on the history channel's modern marvels titled "insulation" -- how they made the stuff, etc etc, and 10 min on doing a house -- sure looked easy nailing that stuff up between the rafters (with plastic air channel between it and the wood, avoiding moisture, etc)), so that sure seemed a lot to me, and I said so.
He then said that he could do it, if we did it RIGHT NOW, for 10K$. Still too much, I said.
Then he said that his men weren't busy this week, and that if we did it RIGHT NOW (ie tomorrow, for maybe 4 or 5 days work) he could do it for $8,500.
--------------------
Not considering the quality of his work (who KNOWS what it might be!), are those dollar figures in the "ballpark"?
And, is his statement that you do the roof, not the floor, correct?
(man, that tv show made it look easy!)
But he said it's a LOT of work -- no, you don't staple it up, nor those plastic air-flow things -- you must SCREW THEM IN, CAREFULLY. etc.
It's my wife's house, and she'll be back from work in three or so hours -- what, from you guys, do I suggest to her?
Haven't had time to get alternate bids yet -- will try to do it via phone-only, asking for any wild-assed guess they might have.
THANKS FOR WHATEVER YOU CAN COME UP WITH, advice, info, etc.
DAVID
(PS: re those windshield wipers, bosh site says that theydon't nave them for ford focus 2000. But another site says they do! Confused!)
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On Jan 20, 2:59 pm, snipped-for-privacy@panix.com (David Combs) wrote:

No. You apply the insulation between the rafters if the attic is finished and heated. Otherwise, the insulation goes between the ceiling joists, with the vapor barrier facing the interior. If you did it the other way around, by not having adequate insulation at the ceiling, you're letting heat travel from the living space into the attic space, which is a waste. In essence, you'd be partially heating the attic.
Depending on what you already have there, blown in insulation may be a good choice. Or fiberglass batts. Curious as to why you say you believe it has little insulation. It should be relatively easy to figure out, no?

Soffits venting to let air in, combined with a ridge vent or other vents up high, eg gable vents, to let it out is best. If you have no soffits, you should have some other vents for the air to come in and then go out via the attic fan. But before an attic fan, you should have good natural ventilation, ie enough places for the air to come in and go out. You may be able to add soffit or other venting.

Total rip off. Ballpark, I'd say it's more than $5k too high Trust your eyes and what you saw on TV. Go down to HD and price out the insulation. You can do it yourself. They even rent the blowing gizmos to do the blown-in type.

That's BS. You staple the baffles and insulation. But as previously discussed, in an unheated attic, you don't want it in the rafters and you don't need the baffles. Except you would use baffles for the first couple feet down by the soffit vents, if you had them, to keep the insulation from blocking the soffit vents.

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>

As long as they didn't ask you to supply the KY Jelly, bend over and take it like a man.
On the serious side, get a couple estimates from established insulation contractors. Or at the very least, a contractor who knows what the heck they're doing.
For my area, that would be an outrageous price, regardless of the type of insulating. This coming from a person who used to be involved in residential insulation. Of course, your area may be much, much, higher.
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You can get a foot of blown cellulose put in for a dollar a sq ft. That will give you R49 in your attic floor. Your 15x8 yard space should only be $1,080. TEN THOUSAND!!!????? no way.
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On Jan 20, 1:59 pm, snipped-for-privacy@panix.com (David Combs) wrote:

10000, you might get it done for 1000. Is floor insulated now, is it unheated and cold, then add more.
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Oh, quick note: am in New Rochelle, NY ("westchester"), maybe 15miles north of north edge of bronx. (45min train ride) to NYC
And, did wikipedia on thermometers then infrared-thermometers (wiki too) and then amazon, which has fluke for maybe $100 and raytek mt6 for about 50 or so (for looking at house for hot vs cold spots) -- both have lasers for measuring the temp (or pointing the thing?)
David
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On Jan 20, 3:52 pm, snipped-for-privacy@panix.com (David Combs) wrote:

If you want to know get a blower door test and Thermal photograph. I have IR thermometers and its deceptive to use, radioshack for 30$. www.energystar.gov has info on insulation
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On Jan 20, 1:59 pm, snipped-for-privacy@panix.com (David Combs) wrote:

You appear to have 1080 square feet (45x24). Around these parts (Chicagoland) for 8 inches of blown-in R30 the price will range from . 75 to 1.50 per square foot depending on ease of access, if they have to block the soffits, non-flat tray ceilings, etc. Because all these things increase the time.
But for a flat attic without soffits (insulation must not get into the soffits) you should be getting this job for $1100 to $1500 or so.
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"David Combs" wrote

Correct. Funny this thread as I know a little on attics but just had to ask for help for my Mom on under a trailer (something i know very little about).

So I gather. Case in point. I lived for a time as a college student in an attic i finished off. It had a casement window on one end and I blocked off the rest of the attic with blankets (looked better than leaving it open and no money for better). Insulating the roof side made little difference to the house proper below the attic due to the windows etc 'other air openings' for ventilation. Doing the floor would have helped there for the main floor. Doing *both* made the attic room fairly habitable as living space in winter while reducing our overall heating bill.
Yours is not a living space so you get most 'bang for the buck' in doing the floor.

Although I've had reasonable relations with folks who just dropped by, this fellow is not reasonable in prices at all.

Nope. Not even close.

Not in your case. It's not a living space and you seem to have a big airflow open to outside in the roof if I understand the attic fan design.

It is.

BWAHAHA! He's not only a rip off, he doesnt understand the job.

Get a real professional if you want but this one really is easy to do yourself. I never even saw a show on it and did my first 'attic' alone when I was 11 with only my sister to help hand the bales up to me from a ladder. This a roughly 2,000 square foot home. If I recall correctly, I did it in about 6 hours and wasnt even remotely rushing. (Mom flipped houses when I was a kid with us 3 kids to help, though we didnt call it flipping then).
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David Combs wrote:

You've got 1080 sq ft. I happen to have recently priced batts at Lowes. Eleven 2x4' 13" R30 in a pack (88 sq ft) for $66. That's seventy-five cents per sq ft., or $810 for your house. Plus tax.
Call it $1000.00 for materials, delivery, misc.
You should be able to install these, yourself, in a week-end.
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ya, and add another $80 and someone else does it for you......
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On Jan 20, 1:59 pm, snipped-for-privacy@panix.com (David Combs) wrote:

As a number of people have pointed out, the estimate appears to be way way too high. Insulation is not that expensive and not that difficult to install. And almost always it should be installed on the floor of the attic (between the joists, and/or on the floor if it is floored) not up by the rafters. The rafter installation is only if the attic is occupied (you've got a bedroom or office or something up there) (which by the way is usually against some kind of local code).
A couple other points - (1) it sounds like you've never been up there. You should go up there and carefully look around. Even if you don't venture beyond standing on a ladder with your head in the attic, you will learn something by looking and seeing what is already there. That knowledge can be helpful when researching the project and talking to contractors about it. For example it would be good to know how much insulation is already there. (2) The way this unfolded should be a lesson. The fact that the person kept dropping the price and urging a quick decision should raise a red flag. A big red flag. Find ways to get reputable people with references when having work done on your home. (3) The attic should have some kind of ventilation besides that fan; for the fan to effectively move air, the air has to come from (or go) somewhere. Is there a vent at the other end of the attic from the fan? Are there any "mushroom" type vents that stick up from the roof? If there really is no venting, that should be corrected in addition to having the insulation added. Good luck -- H
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Oh yes I have, lotsa times.
It's just that the hinge in the middle of the pull-down-and-unfold ladder is looking a bit weaker than it used to, and at 200 lbs, "the boss" doesn't want me breaking the ladder (hmmm, what about my back?).

A guy went up there and did look around (less than 200 lbs!), said that under the floorboards there was indeed some insulation, some OLD OLD insulation, that he said just can't still be much good now.
Also, as in lots of houses, I guess, there's lots of heavy stuff stored up there on the floorboards. Not that that's too important, since there's room to slide it all around, leaving space to do one part at a time.
FWIW, the inverted-V of the roof comes down SMALLER than the house. maybe hits the floor 7 or 8 feet from the outer wall.
Again, the only roof-opening is the one for the attic-fan.
No, no mushroom-things on the roof, no soffits, no nothing -- just the fan (maybe 4 foot in diameter, with louvered barrier to the outside.
Apparantely it would be a lot CHEAPER to do the roof -- much less labor.
FWIW: just today I (finally) ordered books, a hard disk, lotsa books, AND a $99->$58 "ASIN: B000O80B5M" "Raytek MT6 MiniTemp Infrared thermometer" from amazon. Will get here in what, 5 days or so?
So maybe that will help choose what to do?

Thanks for your comments!
David
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On Feb 19, 6:46 pm, snipped-for-privacy@panix.com (David Combs) wrote:

The thermometer will be fun, and will help you pinpoint areas of concern, but it won't help you determine whether to insulate the attic floor or the roof.
If there's a chance that the attic might be finished off some day, and there's enough headroom up there, you might want to insulate the rafters. Do it the right way. Basically everything the surprise-I'm- here contractor told you is wrong, so feel free to purge that information from your memory.
The question of where you should insulate, the floor or roof, comes down to what you personally want to do with the space, how often you plan on doing it and whether you want the attic to siphon off heating dollars from your downstairs living space.
R
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Thanks to all!
David
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