From: Mike Hartigan


In article ,
says...

"Mike Hartigan" wrote in message
Well, here we are in the midst of another winter of sub-zero
temperatures and I'm having the same problem I have every year at
this time. It didn't go away by itself again this year, so I thought
I'd ask for suggestions.

I built an office addition on my house about 12 years ago. There are
two skylights in this room (the preferred lighting alternative to
windows overlooking the side of the neighbor's house). I also have a
central humidifier which does a superb job (Craftsman 3000, 14 years
old, foam wheel type). As the outside temperature goes down, so goes
the humidistat (that's normal). This seems to keep the condensation
on the skylights to a minimum. Indeed, I use the condensation on the
skylights as a guide to setting the humidistat (simple, yet
effective). In case you haven't already guessed, these skylights are
the most condensation-prone sites in the house.

When the temperature gets into the single-digits or below, I have the
conflicting problems of dripping skylights and static discharges
whenever the kids touch other (which seems to happen a lot more often
under these conditions, but I digress). I dont want to reduce the
humidity further, since the static discharges suggest that it's
already too low. I don't want to increase it, since the condensation
suggests that it's already too high.

I have a ceiling fan in that room, and that seems to reduce the
problem somewhat (it doesn't eliminate it), but I'd like a 'better'
solution. Perhaps something to apply heat to those skylights, or
maybe small fans directed at them? Is this a common problem with a
common solution that maybe I'm just not aware of? I've searched and
can't really find anything that addresses this.

Thanks
-Mike

It would be interesting to know if your skylights are plastic/acrylic or
glass. Going out on a limb here, I would venture to guess your lights are
of the acrylic/plastic dome stile.

Pella, Andersen and Velux which are glass, manufacture their skylights
with
a small tray at the bottom of the light. This tray collects condensation
to
help prevent those drips, the condensation evaporates out of the tray.
I've
seen the trays overflow when there is too much humidity in the home.

In twelve years since you've gotten yours, there has been major
improvements
to thermal breaks, R factors and general overall insulating factors in
skylights with glass. If the problem you have can't be tolerated, I would
look at the better skylights. In my book Velux is the best.

These are Velux double pane glass, aluminum/wood construction. No
drip trays, though.

--
-Mike

Are these skylights at the top of a sheetrock "tunnel" from a normal flat
ceiling to the roofline?

If so, I'd access the attic space surrounding these tunnels and insulate them.