答复

1. 
   Charlie Sullivan|Feb 23, 2017 11:07pm|#1

   这是一个有趣的主意。我能想到三个可能的缺点。我认为最严重的是，我怀疑它足够强大，可以阻止浓密的纤维素。我认为这太灵活了。我想您可以添加大量的垫片条，直到得到足够的支撑以避免这种情况，但是这是额外的工作和额外的成本。

   人们可能还会想知道风洗，但是测试表明，在墙壁外部，矿物质羊毛板在这方面还不错，因此应该很好。

   我的最后一个问题是关于空气泄漏。石膏板是主要的空气屏障，但是如果您也可以很好地将挡板密封，这将减少干墙中任何小泄漏的影响。因此，使用矿物质羊毛不是问题，而是如果您使用其他可以使空气紧密的东西，则只是失去的机会。

   So I would tend to opt for something more rigid and cheaper. Plywood or fiberboard are cheaper and still quite permeable.

2. GBA Editor
   马丁·霍拉迪（Martin Holladay）|Feb 24, 2017 04:27am|#2

   布莱克，
   Charlie nailed the answer with his list of three potential problems. I don't think that mineral wool panels make sense for ventilation baffles.

   正如我在有关该主题的文章中所写的那样，Site-Built Ventilation Baffles for Roofs，我认为您不需要担心选择作为通风挡板的材料的蒸气渗透。由于我的文章中解释的原因，我们没有收到任何因使用蒸气障碍而导致的故障报告：

   "What if interior moisture is able to reach the underside of a ventilation baffle — isn’t it possible that the moisture might condense against the baffle (especially if the baffle is cold)? If so, isn’t this a good argument in favor of using vapor-permeable materials (for example, fiberboard, cardboard, or thin EPS) for ventilation baffles?

   "The answers to both questions is a qualified yes. Anyone worried about this possibility should probably make their ventilation baffles out of a vapor-permeable material. That said, there really aren’t any reports of failures or problems resulting from the use of vapor-impermeable materials — for example, polypropylene, vinyl, or foil-faced polyiso — to make ventilation baffles. The main reasons:
   • Not much moisture manages to make its way to the ventilation baffles (especially in homes that pay attention to airtightness);
   •通风通道中的空气通常比室外空气温暖，这一事实限制了凝结；和
   •任何确实通过吸附将其融合到after的水分。通风通道能够从after子中清除有限的水分，看来干燥的速度超过了润湿速度。”

   -- Martin Holladay

3. 
   斯蒂芬·希希（Stephen Sheehy）|2017年2月24日上午08:46|#3

   Blake- since you are still in the design stage, let me suggest another alternative, that we used for our pretty good house.
   我们使用了凸起的脚跟剪刀桁架，24英寸O/c。车顶音高为8/12，天花板的音高更像4/12。从天花板上开始：
   Drywall
   1x4绑带
   air barrier- we used Siga majpell, but there are lots of alternatives.
   纤维素中约24英寸
   flash coat of closed cell foam at the eaves (doing it again, we'd use deeper heels and skip the foam)
   insulation baffles running 4' up from the eaves
   Advantech护套
   underlayment (Titanium)
   standing seal metal roof

   The cellulose was blown in through an access port in the gable end. It was a simple roof, about R 70 or so.

4. 
   Aaron Beckworth|Feb 24, 2017 11:20am|#4

   我们的屋顶设计听起来很像斯蒂芬斯。我们位于新墨西哥州西南部（4B）的高海拔地区，我们的设计已经演变为在850平方英尺的主地板上包括550平方英尺的阁楼。该设计包括抬高的脚跟剪刀桁架，用纤维素吹干和金属屋顶。我们的设计/建筑商似乎并不认为我们需要拱形通风孔或通风挡板。他的想法是尺寸尺寸的山墙端通风口，以提供所有阁楼通风。我非常感谢任何支持或质疑这种想法的评论。

5. GBA Editor
   马丁·霍拉迪（Martin Holladay）|Feb 24, 2017 12:00pm|#5

   亚伦，
   Check your local codes. Most building codes require soffit vents. Here's the relevant section in the 2009 IRC:

   Section R806.2 Minimum area
   The total net free ventilating area shall not be less than 1⁄150 of the area of the space ventilated except that reduction of the total area to 1⁄300 is permitted provided that at least 50 percent and not more than 80 percent of the required ventilating area is provided by ventilators located in the upper portion of the space to be ventilated at least 3 feet (914 mm) above the eave or cornice vents with the balance of the required ventilation provided by eave or cornice vents. As an alternative, the net free cross-ventilation area may be reduced to 1⁄300 when a Class I or II vapor retarder is installed on the warm-in-winter side of the ceiling.

   -- Martin Holladay

6. 
   Aaron Beckworth|Feb 24, 2017 12:27pm|#6

   马丁，
   我将在下次设计会议上重新审视此主题。谢谢你。

   If not for the code requirement, wouldn't eliminating the soffit vents and ventilation baffles greatly simplify the roof design and construction?

7. GBA Editor
   马丁·霍拉迪（Martin Holladay）|Feb 24, 2017 01:42pm|#7

   亚伦，
   Q. "If not for the code requirement, wouldn't eliminating the soffit vents and ventilation baffles greatly simplify the roof design and construction?"

   A. Yes, they would. But you don't want to simplify things to the point that the roof assembly is at risk of moisture accumulation or rot.

   这里有很多因素。一般来说：

   1. Well ventilated roof assemblies are less risky than unvented assemblies.

   2. You really don't want any cellulose touching your roof sheathing -- you want an air gap between the top of the cellulose and the roof sheathing.

   3.如果（a）在绝缘和屋顶护套之间有气隙，并且（b）只要您确定自己的天花板是气密的，您的阁楼也可能表现良好，即使没有拱腹通风口，也可能会表现出色。但是拱腹通风降低了风险。

   -- Martin Holladay

8. 
   Blake Cote|Feb 24, 2017 05:12pm|#8

   感谢大家。我想我会根据您的回答与胶合板一起使用！