Quote:
Originally Posted by cranks
I'm not an expert on this but it's not that the glass fiber itself get moldy but the fact it blocks the air circulation and it holds the moisture can be a problem from what I understand it. Running AC all the time probably helps a lot though. I haven't bought a house in Japan but even I know this much so it's probably one of the reasons surprisingly low percentage of Japanese houses are well insulated. My parents' house, which is now more than 20 years old, is completely insulated but it's built 100% with reinforced concrete which isn't very common in Japan or even in the states.
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I think that in most cases (just shy of 100%) glass fiber would be installed inside of the walls. Even for sound absorption/reduction purposes it is very often installed in the walls. I don't know how most walls are made in Japan, but I know that there are many different kinds of walls you can build. The positioning of the studs and the number of layers of drywall all come into play. At any rate, drywall is usually sealed at the seams with tape and putty-like stuff and then smoothed out. Then the whole wall is covered in like plaster I guess. That plaster can be painted on or covered with wall paper or whatever (to my understanding at least).
So in the case of fiberglass, it's usually going to be put "inside" the walls, which are sealed anyways. Most materials will conduct heat or cold to a certain degree, so having a layer of fiber glass between two materials is good for reduction of that conduction passing through the walls indoors.
Incidentally, the same concept works for low frequency sound. If you have more layers for a sound wave to travel through, it should get weaker (unless you use materials that are particularly sympathetic to sound). Low freq. sound can travel through drywall, so a layer (or two) of glass fiber will kind of absorb the sound wave and kind of "trap" it (which gets converted to energy supposedly). Some of that will still probably bleed through, but the next layer of drywall will reduce it even more to an inaudible level (although really low frequency sounds are less of an audible experience and more of a "feeling").
Any breach in the drywall or structure (like a hole or a crack) will cause air to "leak". Air leakage also means sound leakage. But stopping air seems to mean an increase in mold build up... so it's kind of a catch 22 in a climate like that of Japan.
Something I've noticed is that I seem to see more walls with "wallpaper" than I do with straight plaster. The thing is, the wallpaper is usually textured and almost cloth-like in appearance. I wonder if the drywall (or substitute) is sealed (or finished or whatever you call it) underneath that kind of wall paper.
I've also noticed that houses are usually elevated from the land. I'm sure that helps with mold reduction and rot, but I wonder if cold air doesn't sneak in from under the houses.