The Good, the Bad, and the Moldy
According to freetranslation.com, that translates to Il Buono, il brutto, l'ammuffito
On Monday, the whole group got together to disassemble and inspect the insides of the test walls that have run for a full year at our exposure facility. It was work that I had planned for months now, and it was good to get it done; it was also quite informative and interesting, at least to building geeks.
So we pulled apart our six walls. About half of them were growing mold--don't worry, that's a good thing, and what we expected. It provides us ammunition for demonstrating, "See! A polyethylene vapor barrier can completely screw you over!"
In case you're curious, the idea behind a poly vapor barrier is that it keeps the moisture in your interior humid air in the winter from moving by diffusion (i.e., through a solid material like drywall), touching the back side of the exterior plywood/OSB, and condensing, causing damage. The problem is that it cuts off diffusion all year round--so if moisture gets in, it can't dry to the inside. We would recommend something that stops most of the moisture in the winter, but still allows drying in the summer.
This moldy wall was caused by a different problem--mostly due to running high relative humidity in the winter:
THIS IS WHAT HAPPENS WHEN YOU RUN YOUR HOUSE AT 50% RELATIVE HUMIDITY AND 20° C ALL WINTER LONG! IT IS BAD! DO NOT DO THIS!
In other words, if you see moisture condensing on the inside of your window during the winter, just think what might be going on inside your walls.
Anyway, my throat still feels scratchy from either the airborne fiberglass particles or a reaction to the mold spores. Yuck.
Although I'm glad we got this work done, it is stressing me out that I have three non-thesis-related things to finish as a result (data update, disassembly report, update to some graphs). It was somewhat expected, but it's pushing me even further behind.
The fact that my parents are visiting tomorrow doesn't stress me out--I figure it might be a bit uncomfortable and annoying at times, but possibly a bit fun. It does annoy me that I will be burning a whole day though. And that I'm leaving for a week-long work trip next Wednesday. Argh.
posted by Bats @ 10:37 AM
5 comments
5 Comments:
Do what instead? House needs to be 20C or I freeze. And below 50% RH, won't it be incredibly dry in the winter?
50% RH is the category I would call 'stupid high museum loading.' Even museums, who used to think they needed to condition to 50% RH, have realize how dumb that is--instead, they modify their interior conditions to match their collections (e.g., paper likes it relatively cold and dry; less biological activity that way).
30-40% RH is a lot more reasonable. As my former boss is fond of saying, "humidifiers have destroyed more houses than... well... even architects."
OK. Fair 'nuff. Are hydrometers as cheap as that power meter you loaned us?
A full eight-page paper on relative humidity in buildings and human/health effects can be found here:
http://www.buildingscience.com/resources/moisture/relative_humidity_0402.pdf
A relevant excerpt:
Incorrect recommendations in the popular press often lead occupants and homeowners to over humidify homes during the winter. The range of 40 percent to 60 percent relative humidity is commonly incorrectly recommended for health and comfort reasons. As we will see, there is a big difference between 25 percent as a lower limit rather than 40 percent – particularly in very cold and cold climates.
To complicate things further, most people are not capable of sensing relative humidity fluctuations within the range of 25 percent to 60 percent. If the relative humidity drops below 25 percent, most people can sense it. Similarly, if the relative humidity rises above 60 percent most people can sense it. In the range of 25 percent to 60 percent the majority of people cannot sense any difference. The range of 25 percent to 60 percent is typically defined as the comfort range for this reason.
Yeah, looks like Radio Shack sells them for about $20. You can probably find cheaper ones that are analog.
http://www.radioshack.com/product/index.jsp?productId=2049773&cp=&pg=1&y=10&origkw=humidity&x=16&kw=humidity&s=A-StorePrice-RSK&parentPage=search
Post a Comment
<< Home