Posted on 11/29/2002 1:20:38 PM PST by Jean S
As one of the people in question, I sympathize with your problem.
May I suggest a couple of excellent resources?
Moisture Control Handbook by Joe Lstiburek. Available from Amazon for less than $20.
www.buildingscience.com
If you understand the concepts discussed in these resources, you will be able to tell whether your architect, builder or inspector also does.
Good luck, almost none of them do. And that includes highly educated architects and very experienced builders, even when they're highly ethical.
Their training and experience has just been in other areas. An example is the architect on this thread who claims that insulation is a cure-all for moisture and mold problems.
I am aware of one builder in OH was forced into bankruptcy because he switched to a wall system which increased the R-factor by about 20%. That small increase tipped the assembly over the edge, and structures began literally decaying in a couple of years.
400 homes later, at an average remediation cost of $30k, he was out of business and the buyers were out of luck.
I have a walk-in attic, and when I install my unit, it will be hung from the roof rafters for noise isolation. I sized my own ductwork using a demo duct-design program I downloaded off the internet.
I'll check out that link! I've already cut in 2 6" ducts in the basement, despite the system not being designed for the added load. Its primarily for air circulation down there as it is being converted to living space. I may, in the future, put a system in down there, but it doesn't seem to need it. Humidity is the only issue.
Right now, I am heating the entire 1300s.f. main floor with my Rumford fireplace. I am especially pleased with it's performance, since it is the first masonry fireplace I have ever built.
I'm enjoying central heat, but I also have a vent-free gas fireplace which I use sparingly. I also have a carbon monoxide detector at the other end of that room. :^)
There are about two months in the summer here in WNC where the RH hovers at 95%. Two summers ago, all my furniture and my log walls started to get mold on them. So last summer I installed a 6000BTU window AC unit, which kept the RH at 60% the entire time.
I enjoy similar weather in Southeastern Tennessee. The high humidity along with the coolness of the basement raises the dew point to a level where, if I didn't dehumidify down there, the block walls would condense and remain wet. That is an important issue, particularly in light of this thread.
Incidentally, I bought an energy-star rated dehumidifier and I recommend the same to anybody that buys one. They use about 30-50% less electricity to remove the same amount of water. The energy-star units are relatively new, but Sears, Whirlpool, and others carry them. Since they are a high user, its worth the small increase in initial cost.
Moisture control wasn't a big problem in mild climates before the 70's. Houses were so leaky that air infiltration took care of any buildup. The energy codes changed all that.
In cold climates, moisture control has always been a problem. Human occupancy generates moisture from transpiration, cooking, bathing, etc. This moisture needs to be removed from the living space, or it will condense on the first cold surface it finds. It may be a cold water pipe, a window frame, or the building sheathing. If that surface is within a wall, rot and mold will follow, and exterior paint will peel.
To do the job right in a cold climate, the vapor barrier should be on the inside of the walls, and completely sealed around electrical outlets, light fixtures and such. The tightness should be verified with a pressure test. The outside wall surface should keep the weather out, but be able to "breathe" so that any moisture that does get past the primary barrier can escape.
The reason that you see so many varying opinions on this problem is that there is no one-size-fits-all solution to moisture control. There are about a zillion books on moisture control in buildings at amazon.com. Here is one at random:
Moisture Control Handbook: Principles and Practices for Residential and Small Commercial Buildings
I don't think I've mentioned it before, but vinyl wallpaper, especially on exterior walls, is a disaster waiting to happen. The vinyl prevents escape of water vapor to the interior, so the wall cavity cannot dry. Meanwhile, it hides the evidence that there is a problem inside the wall cavity until it has reached disastrous proportions.
BTW, almost all structures can be remediated. I could have put you in touch with contractors in the Bay Area who really know their stuff. And there is a distinct possibility that you actually had insurance coverage for the problem, even if the insurer told you that there wasn't.
Sorry for your bad luck!
I wouldn't say that. But I would say that anybody who buys a Yugo or Hyundai (although I hear Hyundais have gotten better) and expects it to perform like a BMW is going to be disappointed.
Yet most people think of "a house" as an undifferentiated generic product like gasoline or paper.
By definition, any product purchased primarily on price will quickly reach the lowest possible quality point. Think of airline travel. People purchase almost entirely on price, and we all know what has happened to the quality of the experience. The problem is that an airline flight lasts no more the 4 or 5 hours, in this country. You may be living in your house, purchased on exactly the same criteria, for 30 years or more.
I know houses seem expensive here, but they are built much more cheaply than in Europe or Japan. If I remember correctly, the average cost of the structure itself in the EU is about twice what it is here. In Japan it's 5-7 times greater.
Perhaps not coincidentally, these areas have a lot fewer problems with mold growth. Where they do have problems, it tends to be in the structures which have used building methods more similar to North American methods.
Adding an activated charcoal bed would take care of the radioactive Iodines, too. I guess you would have to keep the activated charcoal in sealed bags, and pour it into the bed if it ever became necessary. (I used to do that stuff at a nuclear power plant.)
There is one problem, though. If the activated charcoal bed gets too "loaded up" with radioactive Iodines, it gets hot and catches fire. Bad thing...
All I know is that after a leak inside the containment structure of a nuclear power plant, the Iodine (fission byproduct) which will be released is supposed to be in gaseous form, which the charcoal beds in the containment structure are supposed to capture.
So maybe the charcoal bed would not be needed after the Iodine had cooled down and solidified.
Southeast Tennessee. A little winter and a lot of summer. :^)
Let me recommend a product which has proven highly effective in retrofitting many structures in hot/humid climates. http://www.thermastor.com/pdf/ua3fold.pdf
I'll look into that!
(No, I have no financial interest in the company!)
The company doesn't seem to understand what they have here, so they don't promote it properly, but the contractors and consultants I work with all over the South are highly impressed with its effectiveness, in many cases.
It's a HEPA air cleaner and high-efficiency dehumidifer that attaches to your existing HVAV system. It takes humid outside air and dehumidifies it deeply, then injects it into the structure. A friend of mine in Tampa is able to maintain his interior below 50% RH even during the most severe conditions.
Interesting. I'm going to look at it, but I'm not sure if it can be applied to my situation or not. I have reasonably dry air upstairs even on the most humid days; typically 50-55% RH. The problem as I see it is downstairs. Its cooler down there, 5-10 degrees typically. Because of that, the water capacity of the air decreases, and if it is humid enough outside, I can actually get condensation on walls. Prior to dehumidification, this was most likely to occur on a day when A/C use was minimal, say cloudy, 80 degrees, and 95% outside RH. This isn't a leak issue; it is a humidity issue.
My solution has been to run a dehumidifier downstairs in the summer, particularly on those not-so-hot days when the A/C duty cycle is low. It is effective and keeps things at 50-55% down there. I suspect that if I had a really large unit or two units, I would have no problem keeping it down around 40% but I think that may be overkill. I'll monitor the situation closely. BTW, I usually use HEPA or close to HEPA filters. I have a 20X30 size filter grill so restriction is quite low.
A beneficial side-effect is that it positively pressurizes the structure, limiting intrusion of hot/humid outside air.
OK, I'm not sure how this works. Does it have a forced air fan pushing air into the house?
Cost: around $3k installed. A major bargain, IMHO.
I'll look into it. I'm not really dissatisfied with what I'm doing now, but I want to monitor it again this spring and summer. Its plenty dry in here now with the FHA furnace and cool outside air keeping humidity down. Its around 38% right now.
There are both positive and negative energy usage effects, which vary by structure. In most cases, I suspect there would be little or no net energy usage increase. But a huge increase in comfort and livability. Not to mention an enormous decrease in the likelihood of mold growth.
Thanks!
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