Roof Replacement and Proper Ventilation
Hello, I live in Maryland (zone 4?) in a home we purchased in 2017 that had recently had the roof replaced. Last year we had a leak during a very heavy rainstorm and realized that when the roof was replaced the sheathing was not replaced and it should have been.
我们想安装太阳能电池板，并希望在我们向前安装太阳能之前解决某些柔软的护套。我相信护套柔软的原因是由于护套下方的排气不当。
你可以看到图片,我强调了specific areas. The area at the top (yellow) closest to the ridge has a very low attic above it with blown insulation and no baffles. The area below that (orange) is a vaulted ceiling in the living room and kitchen. The area below that (blue) is a dinning room that I think used to be an open car port and had an addition put on it. The double blue line represents where I think that the eave was blocked when the the addition was done. The red area is an open entry area with an entry door into the kitchen.
The roof is a 3-12 pitch and has a ridge vent at the top of the yellow section. all of the eves have vents but as I said, I think that further up they are blocked.
As we call roofers to come and provide estimates, I’d like to understand what would be the best way, if at all possible to vent this roof?
To add another level of complexity, we are considering doing an addition to this side of the house in the long term future (5-10) years.
Thank you for your input in advance.
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答复
Low slope roofs are very hard to vent properly. If the soft spots were not from water leaks, your roof might already have issues with leaky ceilings and insufficient venting.
About the only bandaid you can try for the blocked off section is something like a low profile off ridge vent. These are typically used for venting bellow dormers, but some of these can be installed in low slop roof, so you'll have do some digging in spec sheets. Of course, no amount of venting can fix a leaky ceiling, so if any of the sections bellow have something like T&G with no air barrier. That is a much harder problem to fix.
嗨，阿科斯，谢谢您的答复。我一直在研究DCI，Owens Corning和其他制造商的SmartVent Type解决方案，但它们都需要4-12个音高。
I did find this product from quarix that can be used on a 3-12 pitch:https://quarrix.com/Products/Multi-Use-Vent
What if I place this just above where the venting is blocked off and have it vent out at the ridge vent?
我有一个带有CAN灯的干墙天花板，天花板是大教堂的。在这个精彩的网站上阅读了一些阅读后，我现在知道这是一个问题，我需要将其删除或将其密封，我会做的。
That should work, but you need to place it both above and bellow where it is blocked off. You still need an exhaust vent of the roof section bellow as well.
Canned lights do have to go, the simplest is to replace it with slim LED ones. These have a gasket and a pretty strong spring clamp, they seal pretty well.
好....我打电话给Quarrix，他们建议不要使用其进气口，因为我将把它们放在太阳能电池板下。当我按下代表的专门说明为什么我不应该使用它们，他无法谈论细节，他只是说不要这样做，条件不是产品的设计。
因此，我请您的专家提供您的意见。我的选择是将进气口放在太阳能电池板下方，然后将其排出山脊通风口，或者根本不发泄rood。
I can't see what solar panels have to do with roof vents. Maybe if the panels are too close and are sealed around the edge, it would effect airflow.
There are many manufactures that make similar shingle vents like:
https://www.certainteed.ca/residential-frofing/products/certainteed-intake-vent/
You can try giving them a call. The google search term is "shingle over intake vent".
我已经与几个屋顶工进行了交谈，我想我将更换所有的护套。这是非常痛苦的，因为带状疱疹可能是不到5年前安装的。
我将借此机会用坚固的泡沫在屋顶上隔离，我仍在研究自己的选择并成为知情的消费者。是否有人可以推荐任何资源来了解屋顶上的绝缘？太阳能电池板将在屋顶上行驶。2/3的屋顶在大教堂的天花板上，其他1/3处的阁楼上是隔热的，在我的第一篇文章中您在照片中看到的侧面有隔热材料。另一侧是阁楼上有隔热材料的阁楼。
This is probably your best resource:
https://www.buildingscience.com/documents/building-science-insights/bsi-100-hybrid-semblies
The one issue you have is your attic insulation is on the floor not against the rafters. If you seal up the vented attic, you end up with this in between space between the foam and blown in insulation which will create problems in colder climates.
您可以将泡沫公开整个屋顶并保持阁楼的发泄，但是除了您在该部分中固定的R值益处。您正在在泡沫+第二屋顶甲板上花费很多钱，这并没有多大好处。
在你的情况下,可能更简单的方法是pull back the roof deck, spray the ceiling in the cathedral section with closed cell SPF and install a new deck. Keep the other attic sections as is and vented.
Akos, your spray foam suggestion is very interesting.
As it is right now there is not much venting if any in the small area that is the attic. It does have a ridge vent, but I am almost positive the eve vent up to that ridge vent passages are blocked to the attic. Would my solution be to place the quarrix inlet vents where the attic area begins (where orange and red line meet in my pic) and rely on the ridge vent as the exhaust?
Provided there is a high and low vent, it should work. Fixing the leaking pot lights bellow is still a must though.
阿科斯（Akos），如果我最终使用喷雾泡沫选项，则不可避免地会在喷雾泡沫和屋顶甲板之间的位置有气隙，因为它是从外部喷在室内天花板的干墙上的外部。空气空间会引起问题吗？
It is always best to add a bit of venting for this gap. The only moisture source there will be from night time condensation, so it is nowhere near as much air interior air leaks, but still something. Shingles over 15lb felt are 0.6perm, so it would allow for a bit of drying. Doing nothing will most likely work but a bit of venting is guaranteed no issues.
笔记that code doesn't require high and low vents. If you only have one, then you just need more vent area (150:1 instead of 300:1).
@Jon R，您能解释一下更多的排气区评论吗？这是否意味着，如果我没有足够的进气口，我可以用更多的出口通风口来弥补它？如果我只有这么多的山脊到山脊通风口怎么办？
我有几个屋顶工，有几个人提到，他们在3-12或更少的所有屋顶上放了冰和水上盾。我坐在大约2.5-12。
是否将冰和水上护罩放在整个屋顶标准上？
Usually you only put ice and water shield out at the eaves to protect against snow melt water from getting under the shingles and into the roof and walls of the structure. It’s usually two roll widths’ (one really isn’t enough) worth of ice and water shield up from the edge of the roof.
Putting ice and water shield on the entire roof isn’t common, but is occasionally done. With a very low-pitch roof, the ice and water shield gives an extra layer of protection. Shingles work with gravity to keep water out of the roof assembly, but with a very shallow pitch roof and the right conditions water can sometimes “back up” enough to get up under the shingles and then inside. Ice and water shield is a fully adhered membrane (no gaps that aren’t completely sealed), so it’s a waterproof barrier to guard against water getting into the structure that manages to sneak past the layer of shingles.
You have some other options though besides shingles and ice and water shield. You can used roll roofing, which is like a huge sheet that is one giant shingle. Other options are torch down, which is a commercial style roof membrane. These both look very different from a regular shingled roof though, so you may have some aesthetics to think about.
账单
Thanks for the reply Bill.
下面的护套不需要呼吸吗？整个屋顶上的冰和水上屏蔽会影响这吗？
I did a search prior to asking this question here on GBA but got over 100 hits and read through some but couldn't find my specific question discussed. As I was searching through google results I found this GBA thread. It get contentious but has some good insight.
Due to my ventilation challenges under my sheathing I am inclined to only use ice and water shield at the eves. If anyone has any updated info to share it would be appreciated.
//m.etiketa4.com/question/ice-and-water-shield-on-the-the------------------------------------------
Well after may consultations with roofers that I found on the Owens Corning, GAFF, and other vent manufactuer websites, none of them wanted to put in a ridge vent or the low profile intake exhaust vents in my roof because they said that the pitch was too low and there could be leaks from wind driven rain and snow.
我重新测量了我的球场，实际上是4.25-12，它符合或超过大多数山脊和低矮的通风孔制造商所需的3-12个音高。
I found one roofer willing to install these vents and work is scheduled to begin this week.
我有最后一个问题，如果您可以看一下通风口的计划，让我知道您的想法。我对有这么多通风口感到紧张，但我不确定除了根本没有发泄外，我还能做其他事情。
在图片中，您将看到太阳能电池板的去向，通风孔以蓝色标记为已经存在的前夕通风口，红色剖面的通风孔和绿色，以及存在的山脊通风口，但将替换为一个新的。
That does feel like a lot of venting. I would calculate the amount free vent area you need for each section and size the vents for that. The upper attic probably does not need a full length intake vent. Most likely the partial eave vent on the south side and eave vent on the north side would be enough free area.
If there isn't a lot of structure between the cathedral roof and attic sections, you might be able to combine the intake and exhaust vent into a single vent by making a couple of vertical cuts into the sheathing.
The lower attic section can also be gable vented, looks like you should have enough space on the siding for an exhaust vent.