我们的屋顶是1/3 hipped板块，2/3的屋顶用传统的屋顶材料，涂层白色。
我们的屋顶是1/3 hipped板的板岩，2/3的屋顶是用传统的屋顶材料套用的，涂有白色的材料。
几年前，整个屋顶的底面都涂有喷雾泡沫。这所房子建于1930年，阁楼托梁里面有一层岩石。
We’d like to get additional R-value, but don’t want to screw up the expensive foam coating. Thanks for your time & attention.
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Replies
Woody,
几个问题：
1.您在哪里？（或您的气候区是什么？）
2.使用了哪种类型的喷雾泡沫 - 开孔喷雾泡沫或闭孔喷雾泡沫？
3.喷雾泡沫层的厚度是多少？
4.喷雾泡沫是否直接安装在旧的跳过护套和屋顶板的底面？
5.岩壁绝缘在哪里：在阁楼地板上或after子之间（靠在固化的喷雾泡沫上）？
6. How thick is the rock wool insulation?
We're in St. Louis, Missouri.
泡沫似乎是闭孔泡沫。
泡沫约4-5英寸。
It was installed directly on the underside of the roof.
The rock wool is between the joists on the floor of the attic.
这是3至4英寸厚,大约一半的depth of the joist.
The hipped portion of the roof, where there is room to stand and storage space, has plywood covering the joists & rock wool. In order to heat the 2nd floor ( all the radiators were cracked & there was no other way ) we installed a high efficiency gas furnace up in the hipped portion of the attic. ( it releases little heat into the space )
Woody,
It's kind of a shame that spray foam was installed on the interior side of the sheathing on your slate roof. It will make future roofing repairs difficult, since the spray foam glues the slates into a monolithic mass. It also makes it impossible for the slates to dry on the back side -- which is unfortunate but not fatal.
Once the decision was made to install spray foam on the underside of the roof sheathing, those sloped roof assemblies now constitute the thermal envelope of your home. In your climate zone (Climate Zone 4), building codes require a minimum of R-38 for roof insulation. The spray foam layer is rated at about R-29 or R-30, so you are correct that it would be a good idea to beef up your insulation layer.
我希望位于阁楼中的燃气炉是密封的燃烧炉。否则，您会遇到严重的安全问题，因为您的密封阁楼将无法提供足够的燃烧空气来安全操作炉子。（任何位于密封阁楼中的炉子或热水器都必须是密封的燃烧器。）
您的喷雾泡沫层足够厚，可以安全地将可渗透的绝缘材料（玻璃纤维，纤维素或矿物质羊毛）直接用于固化的喷雾泡沫上。但是，您需要提出一种将绝缘材料固定并将其固定到位的方法。这些细节将取决于您对after的东西以及您喜欢的绝缘材料。
进行我们的板岩维修工作的那个人，第二代专家，在2年前的冰雹风暴之后，在冰雹风暴之后没有遇到问题，并取代了受损的石板……这是在安装泡沫之后的。
The gas furnace is indeed a sealed unit. It brings in fresh air from outside, and exhausts the same way.
因此，您要说的是，获得更多R值的唯一正确方法是在托架上安装泡沫上的绝缘材料，而不是在托梁中安装下方？
What's the problem? Would too much heat build up in the attic during the Summer?
If you are heating with natural gas, I can't see you saving very much by just adding attic insulation since you already have.
Woody,
这是关于您的石板修理的好消息。我很高兴您的炉子是密封的燃烧。因此，那些担心被安息了。
建筑法规不认识到将一半隔热材料沿屋顶坡度和一半隔热材料放在阁楼地板上的做法。我并不是说这不会发生，也不是无法正常工作 - 这不是代码认可的方法。
从代码的角度来看，您确实需要在屋顶线上进行R-38绝缘材料。
But, leaving code issues aside, the main problem with installing more insulation on your attic floor is that you lose some of the benefit that comes from bringing your furnace inside your home's thermal envelope. Ideally, you want that heat thrown off of the furnace and ducts to be indoors, not outdoors. The more insulation that you place on your attic floor, the more you are condemning your furnace to spend the rest of its life outdoors.
Not certain we understand the bit about "condemning your furnace to spend the rest of its life outdoors".
不确定我们将如何损失任何东西...房屋中并非所有炉子热信封吗？（无论是否隔热是否很好）
像所有封闭的系统一样，炉子几乎没有加热到阁楼空间。大部分热量都被吹入我们想保留的二楼生活区。这就是为什么我们想将绝缘材料放在2楼天花板上。
We come back to the question of whether Summer heat build-up due to floor insulation would harm the foam.
我们忘了提到，阳光和热量的天窗大约为24 x 48英寸。
Would anything change if we installed an AC condenser unit onto that furnace/blower/duct system?
We have the fittings already installed to connect to an outdoor A/C unit if we decide to do Central Air.
Right now we're making do with window units.
Woody,
Your plan will work, but it isn't optimal. That said, the difference in energy use that we are talking about isn't much.
Unfortunately, furnaces are often installed outside of a home's thermal envelope -- in an unconditioned attic, an unconditioned crawl space, or a garage. This is not desirable, since the furnace and nearby ductwork give off a lot of heat. If the furnace is outdoors, the heat is wasted.
您的情况不是最坏情况的一个例子。您的炉子位于中间空间中 - 并不是真正的室内，也不是在户外。
无论您是否意识到，您的炉子和附近的管道都在释放热量。理想情况下，车顶线上的绝缘材料会很厚 - 保持热量。理想情况下，阁楼地板上不会有绝缘材料 - 因此，炉子和导管散发出的多余热量将能够流过阁楼地板到下面的居住空间。