some particulars then the question. i have a main gable with several large double pane windows that are, for the most part, installed to the outside of the wall. the walls are approximately 8″ thick so the interior wood trim extension jambs are about 6″ deep. i have radiant floor heat and in the winter i will get some condensation on the gable windows partly ’cause the windows are high. i understand the issue of condensation and will address that later but for now i would like to mitigate the condensation on the windows and at the same time make them more energy efficient.
here’s my question. since the window well is so deep i was thinking of installing another window in the well and could use either another double pane window or single pane piece of glass. a local shop builds double pane windows w/o the frame. i would then trim out windows as needed. i could install the new window or single pane glass anywhere from 1″ to several inches to the inside of the existing window. in effect creating a triple + window system but the air space between the old window and new window would be at atmoshperic. i was thinking that any moisture that existed when i install the new window would be absorbed by the trim piece between the existing window and new window. i could also do the best i could to seal the air space between the old window and the new window.
any comments/suggestions? thanx.
Replies
Maybe add a few dessicant packs in the airspace to drawout any trapped moisture in the airspace? Try to install the inner pane on as dry a day as possible. Make sure that the airspace is sealed at all joints to prevent infiltration from ouside of the living space. Try to install the inner pane with future removal in mind if condensation inside creates a mold or mildew issue you have to get in there and clean it. Maybe wipe the inner surfaces with bleach prior to installing the inner pane may delay this. All of this seems stopgap, controlling the condensation in the first place would eliminate the need for all of this.
lost my harddrive. bleach?
I am not clear if you are wanting to install this on the outside or the inside.
But there is no way in h*ll that you will get an air and moisture tight seal between the two glasses.
And discant will only last for a short time.
I would set it up so that whatever ends up being the outside is treated like a storm window. That is it has a small hole to the outside and will allow any trapped moisture to escape.
And you want the spacing about 1". I don't remember the numbers, but I believe that it is about 1.5" that you start getting convective air currents between the glass and the insulation value is reduced.
My understanding was that you start convection currents at anything over .75" spacing. Storm window looks best to me too.PAHS Designer/Builder- Bury it!
lost my harddrive.
new window to be installed on inside. would it be necessary to 'vent' existing window to outside? the exisiting window was built to order and can be removed from existing frame. after removing trim i could drill a small hole thru the frame to the outside.
makes sense about the convective air currents. anyone got a firmer number as i'd like to mount new window towards inside wall.
The basic thing is that if you install a new "inside window" that the you have to have more leakage between the old window and the outside than you do between the two sets of windows.Otherwise moisture from the inside will leak past the inside window and the be "trapped" between the 2.Now that leakage does not need to be much and it might take months or even a year or two, but you will end up worse than you are now.And you don't need a lot of leakage to the outside, but more than you have through the inside window.
Was at a seminar this summer, we talked about this situation. On a deep window well like this, there is too much dead air space that is not the same temp as the room. If the window was flush with the room, there would prabably be no condensation. Simple test, put up some window film on the wall.
Edited 9/11/2005 12:32 pm ET by rich1
at the seminar did they suggest mounting new glass to the inside wall? seal as best as possible from new window to existing window. there is a lot of dead air space and it's not same temp as room...i have radiant floor heat so the natural currents don't get up to those windows. i have noticed if i run the ceiling fans it mitigates condensation a good bit...eqaulizes the temp.
We discussed it more from a troubleshooting point of view. I agree, that trapping moisture in-between would be a long term problem.
Where is this? I saw a few triple glazed windows in Norway and Sweden, but even in cold country like that it's mostly doubles.
-- J.S.
western maryland