Insulation redo in our five year old upper story. Questions about what to do with flat part of the ceiling
As I posted here before, we added 3rd story using attic trusses. The short of it is that the insulation company installed the foam panels on the slanted part of the roof wrong and totally blocked the air channel resulting in mold. Not black mold but a milder kind. We had to gut the whole job.
The mold is remediated we have decided to go with a closed vent system with closed cell spray foam from the old soffit to the ridge vent. The cavities will be filled and are 2×6. The soffits and ridge vents were covered before the foam went in.
The question now is what do we do with the flat part of the ceiling. Do I need put batt insulation in, or can I just drywall right over it as the closed cell files the rafter bays from soffit to ridge? My inclination is that I’d be fine with no further insulation.
I should also note that we will not be insulating the knee walls either as we want to do built ins the whole length or the walls. Given that we’ve switched to a close vent system, anyone see a problem with this? (note: spray foam has already been done so no going back there).
谢谢
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这里的绘图会有所帮助。
If your structure is similar to an A frame, with spray foam in the roof assembly, then the attic space between the peak of your roof and the flat ceiling (which is like the “-“ in the middle of the “A”) is within the building envelope and is part of the conditioned space inside your house. If this is the case, you do not need to insulate the flat ceiling since both sides of the ceiling are conditioned. It is no different from a floor/ceiling between two levels of a multilevel house.
Bill
Zpehyr7,
Yes, they are tradition attic trusses. the flat ceiling is the middle of the "A" or the horizontal line. Thanks for the insight. I agree with your assessment.
我肯定不会在天花板的平坦部分绝缘，因为我觉得有机会在屋顶绝缘层和平坦部分之间可以冷凝，如果绝缘。
Paul,
谢谢. I was leaning that way. This room is sealed from tip to toe, so I am going with the advice from both of you.
谢谢so much,
For 2 layers of insulation to work together they must be in direct contact. So no cannot insulate the rafters and the attic floor whatever layer has the grater R value will become the thermal boundary.
在我看来，你是一个半路完成转换为条件的阁楼。您现在已经密封和绝缘，您必须通过增加供应和返回空气管道来接受苦药并调节阁楼。如果您未能这样做，因此您正在邀请另一个模具节。
After you conversion it would be prudent to monitor your attic. You need to keep the attic warm enough that the attic never falls below the dew point of the air in the living space.
Walta
沃尔特,
我不确定这是正确的吗？首先，我们已经有一个迷你分裂，所以没有什么可以运行。其次，它是顶层和第3楼，他们只是从尖端喷洒闭孔泡沫5 1/2“厚到脚趾。现在是一个不经常的组装。不确定如何存在任何露点问题。
注意，根据我的帖子，这是完整的空间之前，绝缘作业是错误的（空气渠道被天花板绝缘层堵塞，一半的拱腹被阻挡。绝缘公司照顾，真的很棒。
I am curious as to your "dew point" comment inside a thermal envelope with an air sealed closed cell foam assembly that is 5 1/2" thick.
Admittedly, I might be missing something here.
如果您真的想添加更多的绝缘，为什么不先将1/2泡沫带放置箔片，然后在薄膜上。
Tom,
I don't want to add insulation. The spray foam above the flat part of the ceiling is probably 7" thick. on the angle part (above knee wall and below flat part of ceiling) the depth is 5 1/2" on a 2x6 rafter. It's closed cell. I don't want more, I was just wondering if I had to put more. It sounds like I don't.
thanks