Hygroscopic characteristics of mineral wool
Daniel F. Vellone| Posted inGeneral Questionson
任何人都可以比较岩羊毛重新分配冬季水分积累的能力，以及在何种程度上（或不能）在不失去功能的情况下做到这一点。在这方面，我对与纤维素进行比较最感兴趣。谢谢丹尼尔
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答复
丹尼尔，
矿物质羊毛不取水，因此不会失去功能，但它也不会重新分布水分。
因此，任何可能积聚在用岩羊毛绝缘的墙壁腔中的水分都会迁移到螺柱上？
If so, then rock wool doesn't protect the structural wood at all where cellulose actually does protect it?
>“因此，任何可能积聚在用岩羊毛绝缘的墙壁腔中的水分都会迁移到螺柱上？”
没有。
在冬季，大部分水分会首先积聚在（比螺柱更冷）的外部护套中，夏季，它会首先积聚在墙板中（假设内部空调）。
螺柱与护套/墙板相遇的地方，季节性水分含量的峰值将高于螺柱中间。
Dana, you've given me a lot of advice on my wall stack-up and I've finally gotten to the point where I'm deciding between dense-pack cellulose and rockwool having finally found a densepack installer with good recommendations willing to travel to my location. But I can save quite a bit detailing the rockwool install myself. The cellulose quote is a bit higher than I anticipated. **Moisture accumulation is my concern at this point as well - if the rockwool won't cut it I'll have to bite the bullet and hire out the cellulose install. My stackup, if you don't recall, form the outside is 1" hemlock siding, 1" airspace, tyvek, 2 1/2" reclaimed xps, 5" stud cavity, intello plus, blueboard + plaster. *There is no structural sheathing: house is timberframed and the insulation framed has diagonal let-in bracing throughout.
丹尼尔，
With your stack-up you have no condensing surfaces on the exterior to worry about. You can use anything you want to fill the walls.
I agree with Malcolm. The thing you’re trying to protect from condensing moisture is usually the inside surface of the exterior structural sheathing, which is usually plywood or OSB. If that sheathing gets wet, it can rot or grow mold. You don’t have any wood sheathing in that location, and with 2-1/2” of reclaimed XPS on the exterior, you’re in pretty good shape in terms of thermal/moisture performance anyway since that surface won’t be getting very cold. You don’t need to worry about your cavity insulation choice here.
Bill
丹尼尔，你是正确的。
Cellulose is hydroscopic- so it can, as you described, absorb and re-distribute water vapor within a stud cavity. Mineral wool is hydrophobic. It will not absorb and release moisture. Moisture will essentially pass through it as though it were not even there. Same with fiberglass.
玻璃纤维绝对是吸湿性的。它很容易饱和。但是，尽管纤维素在变湿时会膨胀，但玻璃纤维不会，因此变成了块状，无用的混乱。它也不会在干燥后恢复其原始形状。
Trevor I agree that fiberglass turns into a sloppy mess when exposed to bulk water. But in terms of water vapor I still think glass fiber is defined as having hydrophobic properties.
玻璃纤维不像岩石羊毛那样疏水，但都不会很好地重新分配水分，以上都不会防止散装水分侵入。
随着扩散水分和轻微的空气泄漏湿气负荷，玻璃纤维和岩石羊毛将在纤维上搭配一个分子厚的吸附层，并且随着吸附剂饱和，会有一定数量的扇形。纤维素纤维的空心管的特征比玻璃纤维或摇滚羊毛的容量要多得多倍，以在其变成分子厚之前以吸附的形式存储和重新分布水分。
One thing I wonder about is whether moisture-buffering is useful in climates where the high moisture conditions are not seasonal, but are pretty consistent throughout the year?
The usefulness of it seems to pre-suppose the moisture accumulates during the winter, and will dry out in the summer, before the excessive wetting can do any damage. If your climate doesn't have the swings where adequate drying occurs, I wonder if using the wall insulation as essentially storage for excessive moisture is a good idea? Maybe in those climates it would be a better strategy to try and move all the moisture out through the wall as quickly as possible year round? Walls built that way would also perhaps be less susceptible to damage from bulk water intrusions?
Malcolm- good point.
如果冬天足够短，或者内部的热量不够，我可以想象一种场景，即进入腔内的所有内向水分都不会完全逆转墙壁。在某个时候，纤维素可能开始从所有水分存储中压缩？
I suspect there are two things that keeps the cellulose from becoming too saturated:
1. The inward driven moisture is sent indoors through interior, vapor open drywall and removed via AC.
2. Higher outdoor temperatures allow the air to hold more moisture making any outward drying that does take place to be more efficient.
I suspect vinyl wall paper or an interior vapor retarder would cause serious issues. Obviously, exterior rigid foam makes everything better.
Anyway, I'm thinking out loud here. Worthwhile though experiment.
I'm in zone 6, so the presumption I understand is that moisture may accumulate during winter and dry out during the warm months.
丹尼尔，
是的。我更想念炎热，潮湿或温带气候的情况，而没有大幅度的湿度。
马尔科姆（Malcolm），在全年水分水平相当一致的地区，我怀疑纤维素的缓冲能力是否有限（如果有）有限。原因是恒定的水分水平将在纤维素中积聚，直到达到平衡点为止，此时将不可能进一步缓冲。随着季节性的变化，周围环境干燥时，纤维素的水分将下降。随着恒定的水分水平，这种干燥永远不会发生，因此纤维素中的均衡水分位于那里。
I don’t think cellulose is bad in a climate of constant higher humidity, but I don’t think it offers the same benefits there as it does in climates with large seasonal changes. In “always damp” climates it might be better to use something like mineral wool which won’t hold onto any moisture and will allow very rapid moisture migration whenever needed.
Bill
这在季节性变化巨大变化的气候中是否有益于矿物质羊毛的任何好处？我主要指的是矿物质羊毛是一种产品，并且对细节的关注可能是DIY级安装。在这种气候下，疏水品质是否有益？
丹尼尔，
建筑商像丹·科尔伯特的建议nd others who do double-wall construction in New England, is that the moisture buffering is necessary to keep the sheathing safe from excessive moisture during the late Winter and Spring. Whether the presence of a rain-screen gap on it's own would be en0ugh to mitigate the problem I don't know.
从某种意义上说，我问的关于气候中纤维素没有湿度大的气候的问题可能是有争议的，因为这些气候往往足够温和，您的墙壁不够厚，或者保持足够冷以使其变得很重要。
I don’t think it’s a negative for mineral wool in seasonal climates. It MIGHT be a BENEFIT in consistently moist climates like the PNW where Malcolm is. In seasonal climates, I don’t think it’s as much of a benefit, but it doesn’t have the same tendency to get water logger that Fiberglas has which is a good thing.
我在自己的家中使用矿物羊毛，对此我感到满意。我还使用了外部刚性泡沫，这比代码最小的泡沫要多得多，这使得墙上的季节性水分问题要少得多。
Bill
Can't begin to express how appreciative I am for all the advice I've been able to use to make decisions that could have gone the wrong way. I've been working on our new home here for several years myself, plodding along at a snail's pace, but am now closing in on it. After I did the architectural we hired an engineer that advertised a specialty in passive solar, energy efficient design and we learned a little too slowly along the way as mistakes in dimensions in the plan and a general lack of ability to comprehend or communicate in the language and terminology of residential construction revealed the engineer's lack of experience and knowledge. She was in way over her head. We paid the bill, licked our wounds, and turned to you folks and this site's extensive library for advice and guidance that has been invaluable. I appreciate it, Daniel
丹尼尔，
祝您好运，您的构建前进！