Originally Posted by Choro&Swing
(Post 1834018)
Does your home actually HAVE soffit vents? A lot of homes in The Villages DON’T, even if they have ridge vents.
When I started reading Homebuilding magazines in the late 80s, there was a lot about the importance of soffit vents, how much was necessary, how to keep insulation (especially blown in) from blocking soffit vents, how to provide adequate air flow above insulation in a cathedral ceiling, etc. I followed the guidelines when I designed my own house and installed extra vents and careful blocking to keep the 16” of blown in virgin fiberglass in place. However, that was in Pennsylvania.
Mold does not easily grow in a dry attic. Air flow can help dry what is damp. Sometimes. You do not want mold of any sort growing in your attic, wildly dangerous or not. The problem is that for much or most of the year, the humidity in The Villages is around 85%.That’s horrible! (As we all know.) Warm air holds humidity much better than cold or cool air. If you have roof vents that actually work (or a roof fan) and soffit vents, that can pull humid air into your attic. If there are any cold or cooler things in your attic, some of the humidity may condense there and drip. Some building engineers believe that in Florida, NOT having soffit vents means that less humidity gets into the attic. It’s horribly hot up there, and some air gets out when it’s hot, but not much, because there isn’t much air flow through the roof vents if there isn’t soffit venting. The engineers say that instead, put in LOTS of blown-in attic ventilation to keep the living area insulated from that high heat, and let the hotter but dryer attic take care of itself.
HOWEVER, are your air conditioning ducts leaking? They might be! If so, they are leaking cold air, not water. That air has a humidity of perhaps fifty percent, compared to 85% outside, but that is still a lot of water content. That is also your money down the drain, and a lot of it (or up into the attic, rather). That cold air could lead to humid air condensing on the outside of the duct, then dripping through the insulation to the top of the drywall, where mold forms, whether bad or worst. It can also condense at the place where it leaks, and mold can form on that glued fiberglass duct, then perhaps be sucked into your rooms. Some people also have kitchen exhaust fans and bathroom fans vented right into their attic, and that can be a lot of extra moisture that can condense wherever things are cooler.
The best place to have heating and air conditioning ducts is in conditioned space—that is, inside your house—but people tend not to like that. Basements are second best. But we don’t have basements. Unconditioned attics are bad. On the roof is the worst. Traditionally, ductwork was made of sheet metal, but that leaks unless it is carefully sealed, and in a hot attic you would lose a LOT of your air cooling to transfer of heat from the attic. I suspect that all of the main heating and air-conditioning vents in attics and garages in The Villages is fiberglass. This is a mixture of fiberglass and glue, compressed before it sets, then covered on the outside with aluminum foil. This is usually purchased in 4x8” sheets, cut into strips, then glued and taped into rectangular tubes, although it can be purchased already made. (There are also double plastic tubes with insulation and coiled wire inside. Those work well if they aren’t compressed and if they are properly sealed.) These fiberglass rectangular vents are quite fragile compared to sheet metal and can leak if the tape gives way. (Just leaning on them or stepping on them can break them.) They provide an insulation value of R-4, maybe, which is not much, but it is a lot better than R-0 with sheet metal. If they aren’t leaking air, it’s unusual for moisture to condense on them. If they ARE leaking, you can have your air conditioning bill double and have areas in your house that don’t cool (or heat). The plastic ducts with insulation inside are quite a bit better, so long as they aren’t punctured or kinked and are sealed properly. (But a LOT of them are NOT sealed properly, with both HVAC adhesive and nylon ties (like those nylon handcuffs on tv). One place where the fiberglass rectangular ducts leak is in the garage between the air-conditioner and the attic. Leaning on one in the attic can sometimes tear it loose below.
It is certainly possible to tape another inch or two of styrofoam to the outside of these rectangular ducts in your attic. Or, you can buy eight inch thick fiberglass batts and lay strips of it over and around the ducts. As long as there are no leaks, this would stop condensation and virtually stop cold loss in your attic. One warning, though: If you try to do it yourself, it’s easy, providing you don’t have a heat stroke, but if you fail to stand on the joists while working and accidentally stand on the drywall, it can break, dropping you abruptly through the ceiling. That happened to me once.
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