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Old 12-07-2007, 10:57 AM   #1
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insulate floors or attic first?


Here is my situation. Bought a house, floors on first floor have no insulation below in unfinished basement. Attic has some loose insulaltion, but it looks old and there is only maybe 6 or 8 inches of it. None in the ceiling of the attic. Should I do the floors on first floor since there is none there or do the attic since it seems inadequate. I'd like to do both, but cant afford both right now. Which should be my priority?
Also, when doing the attic, can I just put new rolls of insualtion right over the old stuff that is already there?
Im in the Northeast.
Thank you for any info.

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Old 12-07-2007, 04:41 PM   #2
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insulate floors or attic first?


The insulation only goes on the floor in the attic, not in the roof joists. I'd split the attic into two areas. Rake the loose stuff all to one side. Install the new insulation with the vapor barrier in the empty bays and move all the loose stuff on top of it. Install the insulation on the other side and redistribute the loose stuff evenly accross the top. You should have 12-15" when you're done.
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Old 12-07-2007, 04:47 PM   #3
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insulate floors or attic first?


Thanks for the reply. Sounds good. So does the vapor barrier go on top of the wood floor after I rake the loose stuff to one side before putting down new stuff? Is it better to use the pink insulation or blow in insulation?
Should I worry about doing below the floors on the first floor at all, or is it a waste of time and money? Thanks!
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Old 12-07-2007, 05:17 PM   #4
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insulate floors or attic first?


I think the first priority for the basement is to insulate the wood sill that's above grade around the edge of your basement. If you have a masonry/concrete basement that's below grade and the basement is unheated, that's all I do for now. Make sure any windows are airtight. Seal around any services/pipes/etc going out of the house, and up into the living space, and insulate the sill. Then supplement the attic. I'd consider insulating under the first floor a last priority. Sure it'll help, but your temp differential there is probably only 20 degrees. Whereas your temp differential in the attic is likely going to be at least 50 degrees on many nights (depending on where you are in the northeast).
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Old 12-07-2007, 06:26 PM   #5
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insulate floors or attic first?


Thank you Nate,
Im in Rhode Island actually. Sounds like good advice along the lines of what Im thinking. Ive been sealing the basement windows and covering with plastic. Also, adding foam insulation on my newly replaced water pipes.
A bit more to do there, but Im working on it. OK , so I think I should focus on the attic then. Thank you!!

If you have a masonry/concrete basement that's below grade and the basement is unheated, that's all I do for now.

Yes, that is my situation Nate.
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Old 12-07-2007, 07:20 PM   #6
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insulate floors or attic first?


Any money spent on fiberglass is a waste...a box store will sell you cellulose and loan you the blower, half the cost of the fiberglass, and you can blow in a foot of it, and gain a proven R40. I would be very hesitant about taking a rake up in an attic and working between ceiling joists....there is wiring and electrical boxes up there guys.

Blowing an attic is a simple DIY project, and the cost can be as low as .20 a sq/ft doing it yourself, depending on the price on the bags of cellulose. It is also fire retardant, borate treated, and isn't mice friendly material....and the myth that as it settles, you loose R value simply isn't true. Do Google search and compare the products.
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Old 12-07-2007, 08:23 PM   #7
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insulate floors or attic first?


joasis,
So in your opinion, if I just blow in cellulose can I do that right on top of the old stuff that is there already? Do I need something in between the old and new?
Thank you for your reply.
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Old 12-08-2007, 11:25 AM   #8
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insulate floors or attic first?


Also, would it be ok to blow in cellulose over existing rolled out fiberglass insulation?

When you blow out the cellulose, is there a point of diminishing return? Can you blow it out too thick?
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Old 12-08-2007, 03:47 PM   #9
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insulate floors or attic first?


Yes, you can blow it over fiberglass. No, you can't really blow too much, but the R value gain would not be practical after 15 inches or so. We have blown a few to 24 inches, simply because the HO wanted it, but I doubt there was any real savings, since an R50 is pretty tight. A 12 inch fill is practical, and adds about 1 pound per square foot of weight. In new construction, we typically do 9 inches, or an R30+.
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Old 12-08-2007, 07:55 PM   #10
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insulate floors or attic first?


Great! Thanks for the quick reply.
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Old 12-09-2007, 03:34 PM   #11
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insulate floors or attic first?


Just be cautious NOT to screw up venilation chutes or whatever coming up from your soffits. Hard to see what construction or style house you have from here,,,but MOST, homes dont have enough room up there for that deep except for directly in the middle. IF it has vent things coming up for soffits might have to add to THEM or whatever,,,dont just cover them up thinking more is good!!

It also might be handy to KNOW what kind of loose insulation you have now,,,IF its loose fiberglass or glass 2 or whatever the non itchy stuff IS then more of the same seems prudent. I DO like fiberglass better than cellulose cause it stays fluffy longer and recovers from humidity better!!!(ever see a wet newspaper dry out and return to normal??)Might be a 'here' thing!!!Or OLD insulations
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Old 12-09-2007, 05:07 PM   #12
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insulate floors or attic first?


Just so everyone understands that reads this, fiberglass works by holding "trapped" air....now in reality, and there is a ton of material out there to read up on, without it's kraft facing, fiberglass can only "slow" air movement...it's insulation value is way less then stated.

If you think moisture is a problem with cellulose, consider this: We blow it wet in walls in new construction. It dries quickly, and doesn't fall in the wall cavities. If you had it in the attic, and your roof developed a leak, the cellulose will reveal it, and it will not be ruined.

The reason most people do not like cellulose is based on misunderstanding the product.

The Colorado Study Energy Conservation vs. Fiberglass In December 1989 and January 1990 the University of Colorado at Denver School of Architecture and Planning studied the energy conservation efficiency of two test buildings that differed only in the insulation systems that had been installed.
Building "A" was insulated with 5.5 inches of sprayed-in cellulose in the walls and R-30 of loose-fill cellulose in the ceiling. Building "B" received R-19 unfaced fiberglass batts in the walls and R-30 kraft-faced batts in the ceiling.
Over the two-month period a number of different tests and measurements were performed.
Here's what the University researchers learned.
  • In spite of the fact that tests showed Building "B" was about 12% tighter than Building "A" in the uninsulated state, after insulation was installed building "A" was far tighter than "B". Calculations showed that cellulose tightened the building 36% to 38% more than fiberglass.
  • An overnight heat loss test revealed that after nine hours (midnight to 9 a.m.), the cellulose-insulated building was 7 degrees F warmer than the fiberglass building.
  • Most significantly, after three weeks of monitoring the cellulose-insulated building had used 26.4% less heat than the fiberglass building.
In their statement of conclusions the researchers note that results suggest cellulose performs as much as 38% better than fiberglass. The performance advantage of cellulose in temperate climates appears to be about 26%, and the report projects that "this benefit would become more significant in more severe climates."
Cellulose insulation benefits not covered by the University of Colorado study include:
  • Cellulose contains more than 75% recycled material. In accordance with EPA Guideline 40 CFR Part 248 it is the preferred (and in some cases required) building thermal insulation for projects involving federal funds.
  • Since production of cellulose requires much less energy than mineral fiber insulation, which is made in gas-fired furnaces, and foam plastics, which are petrochemicals, the "embodied" energy in cellulose is much lower per "R" of insulating value than other materials. From the national perspective these savings at the production stage must be added to the superiority of cellulose as an insulator.
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Old 12-12-2007, 11:49 AM   #13
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insulate floors or attic first?


is it possible to insulate an open attic by simply purchasing the bags and spreading them out and not renting the blowing machine?

also, how is this applied to walls?
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Old 12-12-2007, 11:57 AM   #14
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insulate floors or attic first?


Quote:
Originally Posted by arichard21 View Post
is it possible to insulate an open attic by simply purchasing the bags and spreading them out and not renting the blowing machine?

also, how is this applied to walls?
Not sure about the walls, but at Home Depot if you buy enough of the insulation to blow they will loan you the blower for nothing.
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Old 12-12-2007, 12:00 PM   #15
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insulate floors or attic first?


For walls you drill a hole at the top of each stud-bay (either through the sheathing by removing a strip of vinyl siding outside, or through the drywall/plaster inside), then you blow it into the wall with the blower.

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