Replies

1. 
   理查德·拜尔（Richard Beyer）|2014年9月8日下午02:50|#1

   George,

   Off-gassing is a risk regardless of CC or OC foam. Roof rot is also a risk regardless of the foam's density. A roofing contractor recently posted on Allison Bailes, PhD blog regarding foam and roof rot. This contractor claims he is removing roofs which have both densities due to rot.

   Everyone takes a risk of odor when they hire a SPF contractor. Industry claims some people are more sensitive than others. I see it as an excuse to a wide spread problem. To minimize your risk industry claims "YOU" need to do your homework on your contractor. The real risk you take is when "YOU" personally experience off-gassing. Is it to late to correct? Many experts say yes and few say no. I am aware of many people who are experiencing what you fear most. Whatever you decide, make sure your contractor is properly insured. ie; Error's and Omissions Insurance, Contractor's Pollution Liability Insurance and Workman's Comp coverage is in place. These policies seem to be the consensus of industry experts to help a consumer who faces odor trouble after SPFI installation. Without these policies you will find yourself eating the cost of remediation and/or years of court costs to recover your damages. Just my opinion.

2. 专家成员
   Dana Dorsett|2014年9月8日下午05:28|#2

   您当地的气候在屋顶甲板上使用开放式泡沫的风险很大。你在哪里？

   It also matters whether the roof deck is plank, plywood or OSB (in ascending order of risk- OSB is the riskiest.)

   Vapor Barrier Latex runs about 5 perms when applied to un-trimmed open cell foam, which is fine in some locations, a disaster in others.

   Any polyurethane foam risks outgassing of polyols, as well as some of the fire retardents used. Only closed cell foam (ccSPF) risks outgassing of HFC blowing agents (which also add to global warming, BTW- use sparingly.)

   在阁楼地板上放置先前存在的玻璃纤维会在屋顶甲板上绝缘时违反代码字母，但在大多数气候/条件下，这并不是特别冒险屋顶甲板。将其留在原位将减少整体加热和冷却载荷，即使它将管道放在热包膜的中间层中。（我怀疑在屋顶甲板和阁楼地板上均不忍受绝缘的主要原因是这样，因此建造者不会尝试使一些R（fore）+ r（floor）= r（最低密码）等式的类型。The Rroof should meet code-min (if you can), but that doesn't mean the insulation on the attic floor still isn't doing significant good, even if it's not as effective as when there is no attic space separating the layers.

   In almost all climates 2" of ccSPF on the underside of the roof deck, and another 6-10" of dense packed cellulose in netting below that would work just fine, despite violating the letter of the IRC:

   http://www.buildingscience.com/documents/bareports/ba-1001-moisture-safe-unvented-wood-ford-frof-systems

   http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_8_sec006.htm

   This works because the 2" of ccSPF is a class-II vapor retarder, whereas even 10" of ocSPF sprayed with vapor barrier latex is a class-III vapor retarder, with about 10x the vapor permeance. With dense packed fiber there will be condensing events at the foam/fiber boundary, but with dense packing the rate of air-transported moisture is pretty slow. Cellulose can even buffer quite a bit of moisture without damage or loss of function.

   如果没有水晶球来准确预测未来的能源成本，就不可能说出任何一个的投资回收期。也很难确定地说，运行现有系统的效率有多大，而管道的密封和绝缘则不那么完美，并且位于绝缘层上方。

3. GBA Editor
   马丁·霍拉迪（Martin Holladay）|Sep 09, 2014 07:31am|#3

   George,
   It sounds like you have done your homework, and you just need to make some decisions. Dana's advice is good.

   许多房主也投资着气候化工作（空气密封和隔热措施），即使投资回收期很长。完成这项工作可能不会出现在投资回收计算中，包括改善舒适度和减少碳足迹。此外，回报计算总是有一些不确定性；对气候化工作的投资将减少您对突然的能源价格峰值的接触。

   如果你有空气处理程序和管道系统在阁楼上, you should do your best to bring your attic inside your home's conditioned space. When this equipment is located outside of your home's thermal envelope, you are paying through the nose for energy that is released into the great outdoors.

   If your roofing is getting old, you might consider installing rigid foam insulation on the exterior side of your roof sheathing, followed by a second layer of roof sheathing and new roofing.

4. 
   George G|Sep 09, 2014 11:28am|#4

   Dana- Are you saying that if I seal my ductwork connections better (i.e. mastic, etc.) and make sure it's insulated properly (right now it'll all insulated-flex, but some are crushed a bit so I'd replace those to increase air flow), that having the air handlers/ductwork in the attic (and the ductwork would be covered in the cellulose, just not the air handlers which would be dammed off), that the payoff b/w foam & cellulose may not be an expensive difference in my case? I've seen a bunch of articles that say air handlers/ducts in attic tip favor in foam, but if that can be minimized...makes my decision a bit easier...

   (edit: Martin - you seem to imply that I may be wrong above...that it still could be very tangible difference in expense. Also, per your suggestion....my roof is in good condition, probably 5-10 years old at most)

   Since you asked, here are the home details:
   -Location：第5区（每个ICCSAFE.org网站4910加热日）
   -Blower门：〜5800 CFM50
   -sq。录像：〜6750平方英尺的总面积；〜6000平方英尺加热的地板区域（2个上层，1个地下室部分地下室，地下1个3车的车库水平，地下室，上面有房间）
   - 乙烯基面，木材结构 - 1982年。100平方英尺的无绝缘悬臂
   - 屋顶：山墙屋顶（2 - 请参见下面的阁楼） - 带有棕色的带状疱疹（面向东北/西南）的胶合板
   - 加热：4个底板加热区，包括地下室1个 - 效率80％
   - 冷却：2个中央空气区（每个地面地板上一个）；1个地下室的除湿机
   -2 Attics (1 for main house w/ hatch, smaller 1 above rooms above garage w/ small door entry – rafters/collar ties, not a truss design) – each with gable vents, ridge vents, and soffits
   主阁楼1：〜5.5“地板上的玻璃纤维绝缘（R-7）；包含2个空气处理机 +绝缘管道（漏水连接…）。包含1个温度控制的屋顶呼吸机
   Smaller Attic 2: ~10.5” fiberglass insulation (R-13) on floor, also some ductwork here
   -Garage ceiling (660 sq. ft) & walls: A few inches of fiberglass insulation currently
   -Rim Joist: Looks like possibly a little fiberglass insulation shoved in there, but don’t think it’s doing much
   -Have 2 bay windows + most of my upper floor
   -Cooling Usage: Keep central air around 73-74 on both floors at all times
   -Heating Usage: Range between 68 (night) to 72 (day)

5. GBA Editor
   马丁·霍拉迪（Martin Holladay）|Sep 09, 2014 11:38am|#5

   George,
   您的措辞方式令人困惑，但我想您想知道如何在这两个选项之间进行选择：

   1. Leaving your air handler and ducts in an unconditioned attic; sealing existing duct seams and verifying that the ducts are in good condition; and adding cellulose to the attic floor.

   2. Creating a sealed, conditioned attic by installing spray foam insulation on the underside of the roof sheathing.

   在我看来,选择2 will cost more than Option 1, but will yield better performance (assuming, of course, that the specs are correct and the work is done well). It's hard to generalize, however, since construction costs vary a lot from one location to another.

   You have to look at your budget and get some bids before you can determine the best way to proceed.