Insulating a sloped ceiling
I’m remodeling my house in Virgina Beach, Virginia, climate Zone 4. On the lower floor I have a sloped ceiling that follows the same slope as the roof with a 5/12 pitch. When I removed the exiting sheetrock the rafter cavities were filled with R30 high density insulation. I have soffit but there are no baffles and there is not exit ventilation such as a ridge vent because the roof of the lower floor meets the vertical wall of the second floor. I’ve seen a product by Lamanco (Omni Vent) or another product called “Smart Vent” that seems to be designed to vent this type of roof to wall design but I don’t want to install these because I can’t find a roofer in my area that have ever installed them and I don’t want to add more areas for possible water leaks. By code I’m supposed to use R38 but the city inspector told me since I’m approximately 400 sqft and only have 9″ rafter cavities I could install R30 High Density and it would pass inspection. I want to do this as right as possible but not spend a fortune doing it and I’m not a fan of foam as there seems to be conflicting pro’s and con’s plus the expense. Questions: 1) Is it OK the simply put R30HD back as a “like for like” remodel? 2) Should I seal up / close up the soffit opening?
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由气候和房屋部分组织的一千个建筑细节的集合
答复
在未通风的大教堂天花板申请中，蓬松的绝缘材料要求麻烦。我要么添加通风口（您也可以使用普通的屋顶通风口，您只需要一个安装在每个顶部附近的after湾）和排气挡板，或者直接使用闭孔喷雾泡沫，直接在屋顶护套的底面。无论您走哪种方式，您仍然需要详细介绍内部干墙空气。在这些类型的屋顶组件中控制水分非常重要。
Bill
Sam,
First, understand that your roof/insulation/ventilation did not meet code at the time it was installed, so the "like for like" argument doesn't hold much merit. Also, while your local code seems to allow for simply filling the cavities rather than meeting new ( or even original) code requirements, that does leave you with significantly less insulation than is currently recommended. So, the "existing" condition is a roof that underperforms from an energy standpoint and is at high risk for condensation and damage. That said, you have not noted and significant condensation and/or mold growth to date, and you've had an opportunity to view the insides of the rafter cavities.
您可以通过将刚性绝缘板涂在内部来使屋顶更好。Polyiso的2英寸将在整个屋顶上增加约R-14，并且还将在afters本身上打破热量。如果您使用箔底面的绝缘材料并将接缝胶带胶带，您的内部将有一个固定的铁瓶蒸气屏障。我已经在4区屋顶上成功使用了这种方法，尽管它确实存在一些风险，这是由于组装两侧的蒸气壁垒。该屋顶不耐受泄漏。如果有任何散装水进入after液腔，它将需要长时间干燥。因此，至少要安装屋顶/侧壁通风产品之一要好得多。最佳性能（和代码合规性）是安装屋顶/侧壁通风口和在下方的空气通道用于连续通风的护套。
Pete and Bill, thank you. You guys have convinced me not to simply go the "like for like" approach and fill the cavities with new R30 and move on. So, the approach I think I will take is as follows: 1) Find a roofer who can install roof/sidewall venting - Any recommendation on what brand or model wall/roof vent to use? 2) Install plastic baffles 3) install new faced insulation 4) make sure all top plates, gaps, penetrations, etc are foamed or caulked 5) Use a foam drywall gasket prior to installing new drywall. 6) Ensure rafter cavity has holes in the soffit to allow intake of air. Does think make sense? Also, here are a couple of photos of stained sheathing, not sure if caused by no ventilation or previous roof leaks. No noticeable leaks or damp areas currently. Thanks again.
That’s mold. That means you’ve had moisture problems in that roof assembly, which is not surprising given the way it was originally built. That mold doesn’t look too bad though. I would clean it with a mold killing cleaner (which can be as similar as vinegar, or use a commercial product). I would then paint over it with a mold killing primer to keep it from coming back. Once you’ve done that, insulate and air seal as we’ve described here and you should be in good shape going forward.
Bill
谢谢比尔，要清楚，你们仍在建议添加屋顶/墙壁排气吗？我在问题＃3中概述的步骤是否需要做？我不想要喷雾泡沫，由于它不是“泄漏耐受性”，所以我不想要Polyiso的2“。真的需要它们。此外，如果我确保在每个腔中打开拱腹，安装挡板但没有出口通风口会有什么危害？我很难找到在这里安装这些安装的人，甚至可以理解我的内容谈论。沿着墙壁的空间为24'，宽14'。再次感谢。