Question about 'R' value for attic insulation.

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I'm in Fort Worth, TX and when I look at an online chart for the 'R' value of insulation I would need for my attic, it tells me 49. (about 14" of cellulose. I think)
At the local DIY store they tell me that this is really overkill and that about 30 will do about all I need.
Since we will be doing the 'blowing in' ourselves, I would appreciate it if someone who has done this themselves, in this area, would care to give their opinion of what 'R' value I will need.
Thanks.
Lewis.
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On 6 Apr 2007 14:08:31 -0700, " snipped-for-privacy@gmail.com"

http://www.fortworthgov.org/uploadedFiles/Development/Development_Guidelines/2003%20IECC.pdf
Specificaly, at tables in the 802.2 section.
Basically, if it's a wood framed structure. R-25 is required if you're putting bats between joists, and R-19 if you blow in continuous insulation.
Remember, that's just code, the bare minimum requirement. If you want to put in more, go for it, your house will be more energy efficient.
Took me about 3 minutes to find by googling "Ft. Worth building codes"
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Also, pay attention to vapor barrier at ceiling level, insulation of ducts above the insulation, & venting. T
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On Apr 6, 6:11�pm, snipped-for-privacy@gmail.com wrote:

or install foam blown in place, R6 per inch
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Need or want? Generally, the more the better, but there is some diminishing return. In your area, it is probably a better benefit for AC than for heating. What is the cost difference doing it the two different ways? $100? Then go for the most. $1000? then I'd go closer to the R30.
As the cost of energy goes up, the return for more insulation gets better. Your energy cost may be 20% to 50% higher in a couple of years so factor that into your decision.
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fwfrog had written this in response to http://www.thestuccocompany.com/maintenance/Re-Question-about-R-value-for-attic-insulation-208024-.htm : Although this post is nearly 2 years old, I find I'm in the same boat, in the same part of town as the original author of this thread. Can anyone advise?
We have a house that's over 80 years old, most brick exterior, roughly 1000 sq. feet with an open attic. We have a gas furnace in the attic as well.
There's a very thin layer of cellulose in place - but it's so bare you can see the 2x4's sticking up all along the attic floor.
We have two companies that have bid to blow insulation in our attic (as they put it, the "white stuff" that looks like "snow").
Here are the bids: R-30 (12 inches) for $200 R-38 (17 inches) for $460 -or- R-49 (inches unknown) for $698
According to the Energy Star chart, we need R-30 at the minimum.
Would R-38 or R-49 be worth the extra cost? Or is this overkill?
Do you have to live in the house for a long time afterwards to see a return in your investment (based on monthly savings in your A/C or heating bill)?
I should also mention that we had a brand new A/C unit (with, I believe, a SEER rating of 14) installed not even 18 months ago.
Any tips would be appreciated! Thanks!
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On Feb 19, 10:16pm, jessmprice_at_yahoo_dot snipped-for-privacy@foo.com (fwfrog) wrote:

White Stuff? what Crack, be specific. www.energystar.gov will help. R 30 is below Minimal. R 40 Is better. R 60 Is great but it will settle 15-20%. I did R 100 and it settled to R 80. Heat rises so insulate better than the Minimal codes require.
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A lot depends on how long you intend to live there. Even if it's a couple years, I would not go with R30 minimum. Not only will you save some on energy, but when you go to sell, it looks better on inspection. Another factor to consider, in addition to $$ of energy, is that the higher insulation can help keep the upstairs feeling cool during summer in TX, especially if you have marginal cooling upstairs to begin with. For the small diff in price you're talking about, and with energy prices likely to be higher in the future, I'd go with the R49. But, I'd make sure to find out how many inches it will be first, so you know if you got what you paid for.
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fwfrog had written this in response to http://www.thestuccocompany.com/maintenance/Re-Question-about-R-value-for-attic-insulation-360452-.htm : Thank you everyone for the quick replies. To address your questions...
The quotes for R-30 and R-38 were for blown-in fiberglass (the "non-itchy", "doesn't catch on your clothes"-kind).
The quote for the R-49 was from a different company. Although I don't know the number of inches, it was written on the estimate as "Climate Pro Blown Insulation". Is this a brand name?
If you can't tell, I don't really know much about the material-type--as most of my descriptions are vague. Sorry 'bout that!
What's a good amount of inches of R-49 to have blown-in?
It should also be noted that we live in a single story house (no upstairs to worry about).
Finally, there's a chance we could sell the house sometime in the middle of summer, due to a (potential) career change.
Then again, with today's economy, we might just stay put for a while.
The R-49 is $500 more than the lowest bid from the other contractor. His R-30 bid is part of a government subsidy program here in Texas. (normally, he'd charge about $450 for R-30, but the program knocks the price down to $200)
I've read that R-type doesn't matter in Texas as much. Or that R-38/R-49 do more for cold weather areas than hot climates.
I'm trying to learn on the fly- but it seems there's so much contradicting information out there!
Thanks again, everyone...
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On Feb 20, 12:18pm, jessmprice_at_yahoo_dot snipped-for-privacy@foo.com (fwfrog) wrote:

Don;t know, but if it is, you can probably find it by googling a bit.

It's not that you get X inches of R49 blown in. It's the number of inches that determine the R value. Using the same material, you could get any R value. Which is why I suggested you nail down what they are using and how many inches you're getting.

One things for sure, you're not going to recover the $500 diff in cost in 6 months, or even a couple years. I would think there might be some calculators online to help guestimate. Try googling for "insulation savings calculator"

I'd check for state websites for info on how this program works. Usually, they are trying to encourage people to put in more than the minimum. It would be stupid for the govt to have a program where they just give a credit towards the minimum and you get nothing if you do better. But then from what I've seen lately, nothing would surprise me.

There is some truth to the cold weather part. Heat loss is proportional to the temp difference. So, if you're keeping it at 70 inside, if it get's to 100 outside, that's a delta of 30. I it gets down to 20, that's a delta of 50. So, there are more areas of the US where the heat loss in winter is going to be the greater concern.

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snipped-for-privacy@gmail.com wrote:

There are local minimums. I consider them just that. More is always better, but there comes a time when it becomes un-economical to go higher. Few people go that high. More efficient systems will mean less payback from insulation, but as time goes on, you can bet the cost of energy is going nowhere but up so I would suggest erroring on the high side. Don't forget to add additional insulation for any ducts that are running up in that attic.
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Joseph Meehan

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Your original post said you were blowing yourself. I hope you saw the reply about vapor barrier. I am near Chicago and our requirement is R 30. Typically a 6" R-19 batt with vapor barrier (always facing the inside) then blow on about 6 inches to get a consistant blown R-11 after settling. The next big issue is the attic ventilation. Buy foam chutes at the local home store to prevent the insulation from contacting the sheathing near the edges. This allows air to travel from the soffit vent up to the high roof vents. Without proper vapor barrier and ventilation you don't gain from insulation, it causes more trouble.
Dave Scudamore Aroundtoit Handyman
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On Apr 6, 11:45 pm, snipped-for-privacy@gmail.com wrote:

Thanks.
I'm working on the soffit vents and baffels.
WOW! This stuff makes a yoga class look like a walk in the park. :-)
Lewis.
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On Apr 6, 11:45 pm, snipped-for-privacy@gmail.com wrote:

We are adding on to our house, and when I talked to my inspector about vapor barrier, he downplayed the need for it, indicating that we could use a primer under our paint which would be rated as a vapor barrier. He said that as long it had a rating of 1 perm, it would be ok.
JK
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Big_Jake wrote:

If he made that remark related to the idea of removing existing insulation in order to add a vapor barrier, I would suggest that it might not be a bad idea. On the other hand if he is talking about skipping the install of a conventional vapor barrier during a conventional install, I would suggest ignoring almost anything he says.
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Joseph Meehan

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wrote:

Since he will be signing off on my permit, ignoring him would be really bad. :-)
JK
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:

The electric utility in Tucson AZ (where its hotter than FW) says to go with R 30 Above that is a waste of $$
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I know they make a paint that is supposed to be a vapor barrier. I would want to hear it from the paint dealer that his product is a full and complete replacement for the attic vapor barrier, not just a supplement. I owned and operated a home inspection company in the early 90's. You would be amazed at how many houses had the insulation installed upside down. Obviously, the city code inspector passed them when it was built. This traps vapor (read water) in the fiberglass with no means to disperse. Molded drywall results. If the warm moist inside air contacts the colder atmospheric temperature of a properly vented attic, condensation occurs. I know you don't have varying temperature like we see in Chicago but if they specify that much insulation they must expect it to insulate the home interior envelope from some exterior temperature extreme. Better safe than sorry.
Dave Scudamore Aroundtoit Handyman
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On Apr 7, 8:47 pm, snipped-for-privacy@gmail.com wrote:

Codes on insulation are minimums never the optimal, nor do they reflect present utility costs or future increases, most are way outdated. Whatever you put in it will settle, cellulose will settle the most and deteriorate as its only paper. My fiberglass settled 15%, for cellulose Id figure double as a guess. If winter heating is minimal a vapor barrier may noy be as big an issue as it is up north, Put in what is optimal, your DIY store employees really dont know.
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the more you can afford to put into the space, the more comfortable the house will be. we have always added new insulation into every affordable wall and floor.
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