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Old 03-02-2012, 10:30 AM   #16
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cover insulation in attic?


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Fire board is fire rated drywall such as 5/8" either way you need a fire break on the wall.
Really? I don't think I've ever seen drywall inside an unfinished attic.

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Old 03-02-2012, 10:54 AM   #17
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cover insulation in attic?


Doesn't necessarily require drywall but it will have to be either approved or require a specific ignition barrier.

Fiberglass may be suitable.

http://sprayfoam.com/leps/letitem.cfm?letid=37
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Old 03-02-2012, 12:33 PM   #18
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cover insulation in attic?


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Doesn't necessarily require drywall but it will have to be either approved or require a specific ignition barrier.

Fiberglass may be suitable.

http://sprayfoam.com/leps/letitem.cfm?letid=37
As I read it, this deals with commercial buildings, not residential. Did I miss something?
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Old 03-02-2012, 12:59 PM   #19
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cover insulation in attic?


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Originally Posted by Jeremy Hillary Boob, PhD View Post
As I read it, this deals with commercial buildings, not residential. Did I miss something?
Yes.

Ignition Barriers: When foam plastics are used in attics and crawlspaces, they still must be separated from the interior space with a thermal barrier. However, in attics and crawlspaces where entry is only for service of utilities (not used for storage or living space), the foam plastic may be separated from the space in the attic or the space in the crawlspace with an ignition barrier instead of a thermal barrier.
Code designated ignition barriers include:
  • 1-1/2 inches of mineral fiber insulation (rockwool or unfaced fiberglass)
  • 1/4 inch of wood structural panels
  • 3/8 inch particle board
  • 1/4 inch hardboard
  • 3/8 inch gypsum board
  • Corrosion resistant steel having a base metal thickness of 0.016 inch.
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Old 03-02-2012, 02:58 PM   #20
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cover insulation in attic?


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Originally Posted by Windows on Wash View Post
Yes.

Ignition Barriers: When foam plastics are used in attics and crawlspaces, they still must be separated from the interior space with a thermal barrier. However, in attics and crawlspaces where entry is only for service of utilities (not used for storage or living space), the foam plastic may be separated from the space in the attic or the space in the crawlspace with an ignition barrier instead of a thermal barrier.
Code designated ignition barriers include:
  • 1-1/2 inches of mineral fiber insulation (rockwool or unfaced fiberglass)
  • 1/4 inch of wood structural panels
  • 3/8 inch particle board
  • 1/4 inch hardboard
  • 3/8 inch gypsum board
  • Corrosion resistant steel having a base metal thickness of 0.016 inch.
Well, I'm still not getting it. I thought the IBC was for commercial buildings, while the IRC applies to residential. The link (and quote) you give seem to be from an IBC document.
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Old 03-02-2012, 04:39 PM   #21
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cover insulation in attic?


IRC Section 316.5.3 states the following:

Exceptions to the Thermal Barrier Rule: There are exceptions to the thermal barrier requirements in the IRC code listed in Section 316.5. The following items are a few examples listed in the IRC code.
  • Foam plastic covered a one inch thickness of concrete or masonry
  • Foam plastics used in roofing applications (although roof coverings must be tested using other methods.)
  • Bare sprayfoam 0.5 to 2.0 lbs per cubic ft density (open or closed cell) can be installed without a thermal barrier to sill plates and headers so long as the foam is a maximum thickness of 3.35 inches, has a flame spread rating of 25 or less and a smoke developed rating of 450 or less in accordance with ASTM E-84.
  • Attics and crawl spaces do not require a thermal barrier and can use an ignition barrier instead.
Ignition Barriers: When foam plastics are used in attics and crawlspaces, they still must be separated from the interior space with a thermal barrier. However, in attics and crawlspaces where entry is only for service of utilities (not used for storage or living space), the foam plastic may be separated from the space in the attic or the space in the crawlspace with an ignition barrier instead of a thermal barrier.
Code designated (prescribed) ignition barriers include:
  • 1-1/2 inches of mineral fiber insulation (rockwool or unfaced fiberglass)
  • 1/4 inch of wood structural panels
  • 3/8 inch particle board
  • 1/4 inch hardboard
  • 3/8 inch gypsum board
  • Corrosion resistant steel having a base metal thickness of 0.016 inch.
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Old 03-02-2012, 06:11 PM   #23
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cover insulation in attic?



OK, got it.

It looks like that might be more trouble than it's worth. So, maybe I'm back to square one---cover the fiberglass batts with Tyvek and be done with it...
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Old 03-02-2012, 06:44 PM   #24
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Not that big and issue.

Cover it with some unfaced fiberglass and you are all done.
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Old 03-03-2012, 12:08 PM   #25
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cover insulation in attic?


Or, just install some Thermax , tape the seams with foil tape. Ask your local AHJ about this to be sure.
http://www.icc-es.org/reports/pdf_files/NES/NER681.pdf

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Old 03-03-2012, 01:07 PM   #26
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cover insulation in attic?


I had to put 5/8's drywall on mine to pass inspection,regardless if I used foam or not.
That is just how the inspector wanted it.
It wasn't a big deal at the time because I had the walls opened up which gave me plenty of access. At the time it seemed like it was over kill.
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Old 03-03-2012, 11:16 PM   #27
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cover insulation in attic?


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Or, just install some Thermax , tape the seams with foil tape. Ask your local AHJ about this to be sure.
http://www.icc-es.org/reports/pdf_files/NES/NER681.pdf

Gary
That looks like the best idea so far. Thanks.
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Old 03-04-2012, 08:58 AM   #28
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cover insulation in attic?


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Originally Posted by GBR in WA View Post
Or, just install some Thermax , tape the seams with foil tape. Ask your local AHJ about this to be sure.
http://www.icc-es.org/reports/pdf_files/NES/NER681.pdf

Gary
Btw, does anybody know where to get this stuff? A local Home Depot used to carry it, but not now.
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Old 03-04-2012, 12:36 PM   #29
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cover insulation in attic?


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Originally Posted by Jeremy Hillary Boob, PhD View Post
Btw, does anybody know where to get this stuff? A local Home Depot used to carry it, but not now.
Most big box stores have it.

All you are looking for is a foil faced poly-iso.

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