[Greenbuilding] condensation on storms

Benjamin Pratt benjamin.g.pratt at gmail.com
Sat Oct 26 10:14:53 CDT 2013


Thanks all for your advice.
We use a bath fan and do what else we can to control humidity. It would be
nice to install an erv or hrv but budget and time constraints don't allow
it now. We are also having a very cold fall and I have a lot of projects to
get done, so internal storms will have to wait.
   The advice that I will use right away is to also caulk between the trim
(casing) and the wall. The casing is stained, not painted, so I hadn't
caulked it (since it won't look nice). But I'm a good caulker, so I will
run a very small clear bead, or perhaps pry up the casing a bit, put a bead
down, then put the casing back.
  The aluminum storms could be drilled or cracked open, but I understand
this will increase heat loss, so I will try not to.
   I will also look for some way to add desiccant between the windows and
the storms. (any suggestions/links)?
  The former owner put in new windows, but they are the kind where you only
install side tracks and the sashes. They are very leaky and I would not
recommend them!
  Also I haven't tried clear polyurethane caulk. Does it attract dust?
Should I use it, or silicone?
 thanks again!


On Thu, Oct 24, 2013 at 2:25 PM, RT <archilogic at yahoo.ca> wrote:

> on Wed, 23 Oct 2013 23:39:42 -0400, Benjamin Pratt <
> benjamin.g.pratt at gmail.com> wrote:
>
>   Although I caulk all my windows with removable caulk every Fall, the
>> storms always get quite a bit of condensation on them, especially on the
>> top floor in the rooms adjacent to the shower.
>>
>
> Ben;
>
> My parents' century-old home used to have wooden-sash exterior storm
> windows that were put up every Fall and removed every Spring.
>
> On the bottom rail of the sash there four 1.5 - 2 inch holes arranged in a
> pattern  and there was a pivoting flap which could be opened as required.
> As a kid I just assumed that those ventilation holes were to allow fresh
> air into the house if desired. In later years it occurred to me that they
> were to facilitate drying of moisture build-up between the double-hung
> windows and the storms.
>
> About 30 years later when building my own home, I installed Pella [spit!]
> windows because they were considered the best ( but in reality, just the
> best promo literature).
>
> This was back in the days when they offered a removal interior pane which
> clipped into the wooden sash and used compression bulb gaskets to provide
> the air seal.
>
> Unfortunately, the folly of Pella's [spit!] design became apparent the
> first heating season when condensation formed against the inner surface of
> the exterior pane of glass. Pella [spit!] had designed the wooden sash with
> two 3/8" dia holes drilled through each of the four rails, with plastic
> sleeve inserts in each of the holes which could capture a plastic ball
> "plug".
>
> Which of the holes received a plastic ball plug was determined by the
> orientation of the sash.  (ie Awning window sash are casements flipped 90
> degrees).
>
> Some of my windows had fogged up because paper wasps had plugged up the
> ventilation holes with mud.
> D'Oh!
>
> You may be too young to remember but there was a time when sealed
> insulating glass units sometimes had a small breather hole drilled through
> the outer pane of glass in an upper corner to allow moisture between the
> panes to cook off.
>
> The point of all of the above ? In the past when window makers
> acknowledged that they had difficulty making a perfect air seal, they
> provided ventilation holes in the outer pane to exhaust any moisture that
> got into the air-space.  In century-old homes, where air-leaky sliding sash
> and trim were common-place, the ventilation holes were huge (ie 4 x 1.5-2"
> dia holes)   In Pella [spit!] windows in the 70's & 80's of the previous
> millenium, where the window units are kinda tight, the vent holes would be
> two 3/8" dia holes.
>
> In old sealed insulating glass units, the vent hole would be one 1/8" dia
> hole.
>
> The size of the vent holes that you'd need would, I imagine, fall
> somewhere between Pella's [spit!] and the
> 1/8" hole in the old IGUs.  That would be the quick/dirty solution to your
> problem.
>
> The better solution would be those mentioned by Mike and Topher ...
> interior storms with very good air seal and lowering interior humidity,
> either by exhausting it at the source and/or dehumidification.
>
> Unfortunately for me, those Pellas [spit!] that I installed in my home
> have proven to be very longevous
> (no edge seals to fail, aluminum cladding on frames and sash) so they're
> still being used. I dealt with the lousy air seal of the removable inner
> pane by making interior storms which snap into the space which the
> (inteior) insect screens vacate when cold weather comes.
>
> I went to the local H4H ReStore and got a bunch of 4 mm glass that was
> used in 1950s-era sash-less sliding windows and inserted the glass into
> mini-frames made out of 0.5 " x 1" pine, with Shoji/Greene & Greene-style
> muntins to restrain the long flimsy perimeter pieces. The interior storm
> creates a 13/16" air-space.
> The interior storm sash is made smaller than the actual opening to allow
> for a screen spline "gasket" to be compressed into the gap to provide the
> air seal. The screen spline is reusable year after year but you could use
> your peelable caulk if you can't be bothered futzing with the screen spline.
>
> As a belt & suspenders strategy, I also insert a piece of silica
> gel-filled spacer bar (salvaged from dismantling patio door IGU) at the
> bottom of the air-space and include a brake-formed sheet metal condensation
> gutter (to match the profile of the bottom sash rail (set in place before
> the storm is put in).
>
>
> --
> === * ===
> Rob Tom                                 AOD257
> Kanata, Ontario, Canada
>
> < A r c h i L o g i c  at  Y a h o o  dot  c a  >
> (manually winnow the chaff from my edress if you hit "reply")
>
>
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-- 


b e n j a m i n p r a t t

professor art+design
the university of wisconsin stout
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