How to treat wet sandy cottage crawlspace in zone 5A/6A?
Situation: cottage on the sandy shores of a large lake in Michigan on the border of climate zones 5A and 6A. The cottage is set back from the lake front perhaps 200 feet, but is probably less than 2’ above lake level. The footings are likely below lake level. To make things worse, there is a natural drainage swale running behind the cottage that some good neighbors have effectively dammed, so there is permanent standing water about 100’ behind the cottage.
因此，小屋当然是用爬行空间建造的，有沙子地板和混凝土砌块墙。
Other details: well and septic, baseboard heat, no a/c or dehumidifier. There are about 20 air vents around the crawlspace perimeter, but most have been closed. The cottage is infrequently used at this point. Perhaps 15 years ago, moisture was an issue (shocking), and the cottage was raised perhaps 2’ so that there is now roughly 40” of crawlspace wall exposed. From the times that I’ve been into the crawl, I’d say the sand floor is damp but only occasionally has a small amount of standing surface water in a few spots.
The cottage is a special case for moisture because the air is unconditioned (humidity and temperature are not controlled as in a full-time house) and because the crawlspace is very wet and closely coupled with the rest of the house.
Conventional crawlspace wisdom says to seal up the crawlspace and bring it into the building’s conditioned space. Add a sump pump, and you should probably insulate the crawlspace walls while you’re at it. And then there’s code for conditioning unvented crawlspaces, requiring connecting the crawlspace to conditioned upstairs via transfer grille and then either adding an exhaust fan or a forced air register. Not that we ignore code, or promote ignoring code, but let’s ignore code for a moment.
The problem with this cottage is that there is in fact no “conditioned” air space, other than a bit of baseboard heat during the winter (thermostat set to 50F).
The specific question: is sealing the crawlspace, by itself, worth doing? If we sealed the crawlspace walls and floor with a 20mm plastic liner and did a complete job of sealing the vents, but didn’t add a sump pump (we can’t drain the lake), and didn’t add a 100 pint/day dehumidifier, would the liner improve things significantly? And by that I mean slow decay of the building?
感谢您的想法，
GBA Detail Library
由气候和房屋部分组织的一千个建筑细节的集合
答复
将爬网空间等级提高到您没有得到水的程度。然后空气密封，隔离并与塑料排队。然后是：
a）除湿空间。这是最好的，并且不会花费太多（因为大多数水分来源已被阻塞）。或者
b)保持大量的气流向外。crawlspace insulation and plastic will reduce moisture levels from what you have now.
谢谢乔恩。
我可以通过添加沙子和/或升级现在的东西来提高爬网空间的地板。真的有任何危害来自完全密封的衬里下方的一些积水吗？这不是可以看到任何人流量或存储空间的区域。
我有点怀疑您的选项b）不会很好，因为它没有从上方抽出条件的空气，而只是在房屋中过滤无条件的户外空气。因此，您可能对除湿机是最佳选择可能是正确的。
我仍然想知道我们是否可以在没有加湿器的情况下逃脱，或者我们是否在没有它的情况下浪费了衬里。
I think you will find that while the plastic is a good vapor barrier, it isn't a reliable water barrier. But there may be other ways to raise the plastic that are easier than sand fill. Perlite?
即使没有除湿化，衬里也很有用。我不知道确切的效果b）会有多大的效果 - 您可以用除湿计划作为备份计划尝试。
Andrew,
我要第二个乔恩提高爬行空间地板的建议 - 我会使用压碎的石头，但我想沙子会起作用 - 然后安装了重型聚乙烯蒸气屏障。这两个步骤可能足以显着改善爬网空间。进行这些更改后，您可以监视情况 - 您可能不需要除湿机。
感谢您的反馈乔恩和马丁。
我将尝试确切地弄清楚过去的水有多大，然后看看我面临的任务要抬高爬行空间地板。
Will also have to look for some ideas for moving building materials (gravel, sand, perlite, other?) around in height constrained places.
可能在混凝土或可流动的填充中泵送。外部排水？是机械/供水吗？除非您需要调节全部或某些crawspace，否则我将使用排水管和最大通风。在地板上隔离。
即使在50 f条件的空间温度下，也值得在气候下绝缘爬网空间墙，更可取，比托梁之间绝缘。（在用电踢脚板上加热时尤其如此。）托梁之间的绝缘降低爬网空间中托梁边缘的温度，增加了对机械除湿的需求，并增加了冷冻管道的可能性。绝缘爬行空间墙会提高爬网空间的温度，从而减轻这些风险。
在CMU墙上的几英寸的火额定刚性多丽莎胶胶和螺丝螺丝是一个相对容易的DIY。如果使用聚苯乙烯或未带来的聚硅码将需要对泡沫和爬网空间之间的点火屏障，这增加了时间和材料费用。如果使用polyiso，请确保地板蒸气屏障在墙壁泡沫和CMU之间的墙壁侧面覆盖。
如果考虑到空调，寒冷的气候微型散布热泵可以将冬季供暖费用一半以上（如果在肩部季节使用该空间，则占领的肩部季节供暖费用2/3或更多。）即使在其正常加热模式下的最低加热设定点以下，也可以设置Fujitsu＆Mitsubishi以保持〜50F。富士通具有约50F的“最小加热”模式，可以使用其“智能设置”模式设置三菱，直到/除非您阅读并吸收用户手册中的所有内容，否则这并不明显。可以肯定的是，寒冷的气候热泵是窗帘式AC的相当高收费，但不是从温暖的气候热泵或仅冷却的迷你切片中获得的荒谬的上升。即使是温暖的气候微型分类，在暖气季节仍然可以节省金钱，但即使在50F室内的室内装载量（如果用于冷却负荷），则可能在99％的外部设计温度下具有足够的容量如果整个冬季都使用，则在室外单元的底部底盘上造成损坏。（寒冷的气候迷你切片有锅加热器可以自动避免该问题。）