I am a neophyte home owner in the Milwaukee, Wisconsin, area and have a
question about an unusual problem. I bought the home recently, which was
built in 1991. I have a finished basement with 2 bedrooms. The ceiling of
one of the bedrooms took on a lot of water and cracked and nearly collapsed.
There was no previous sign of water damage on both professional and personal
inspection. When the ceiling was torn down, the cold air return showed so
much condensation that it was dripping off the pipe. The return is
uninsulated; a furnace technician told me it is normally not insulated. The
other parts of the ceiling structure showed no water accumulation and the
plumbing was intact with no signs of leakage. There is no other signs of
water accumulation in other parts of the house. The return is being
insulated today before the ceiling is rebuilt.
The contractor, furnace technician, and friends I have discussed this with
all have never heard of this problem. As some of you know, the mid-west is
very humid and hot in the summer and I used the air-conditioner liberally.
Have any of you heard of this type of problem?
Thanks much in advance for any insights and advice.
Sounds as though your basement air, is especially warm/humid and
probably fairly static above your basement ceiling. Do you have
any 'slight rust' problems in basement are. For example do metal
tools show very slight rust after few months or any similar
indications? I know that we humans breathe out quite an amount of
moisture and if people sleep down there it will be a for a
significant percentage of the 24 hours. Can't remember the amount
we breathe out but is it something like about a quart per day?
Quite apart from any sweating we do?
To have condensation like that on the cool air return pipe from
upstairs or wherever the return comes from, means that the
returning air is cooler than the warmer and apparently much more
humid air surrounding it above your basement ceiling. Maybe the
upstairs is air conditioned so that its air is cooler than the
air in the basement?
Is the basement sufficiently ventilated or do you need to
decrease humidity down there by use of a dehumidifier? We use a
dehumidifier in part of our basement. Got one of those
instruments you hang in the hall to tell the humidity and
barometric pressure? If so or can borrow one you could measure
the relative humidity down there in comparison to upstairs.
Probably won't be very accurate but will give you some idea of
the relative humidity.
That's the problem; whenever warm humid air cools down the
moisture in it condenses and turns into water! That's how a
dehumidifier works, why fridges have to defrost (or be defrosted)
and that's how rain is formed. Air conditioned air will also have
lost some of its moisture just by virtue of being cooled!
Few ideas anyway.
Get a new tech, cause he is wrong.
He needs to get up to date, since for a while now, the Mechanical Code has
referenced the Energy Code book, and it states, CLEARLY
503.3.3.3 Duct and Pleum insulation
All supply and return air ducts and plenums installed as part of an HVAC air
distribution system shall be thermally insulated in acordance with Table
1, does not apply to your case, but #2
2. Ducts within the conditioned space that they serve....meaning, IF the
duct was exposed, and not in a wall, or ceiling, it could be non
Also, the table shows that if it is in a unconditioned space, such as a
crawlspace, (not attic, as attics are manditory by code to have insulated
if the TD is less than 15F then it can be uninsulated.
Otherwise, to keep from having the problems you have had, insulate it.
Every day...it seems.
Saw it in CA too....its a common problem when someone tries to save a buck.
and that is about all they save too....
Here in NC, its been a sauna, and we took on a complete re-duct this
week...same issues...and again...VERY common when someone cuts a corner.
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