[JamesRW]

I am interested in anyone's experience and/or advice regarding interior storm windows. I have researched this and am aware of most of the options available. The Larson interior storms are not available for most of our windows due to their size limitations. Other types I have seen consisting of the double mylar layer seem a little pricey for a somewhat "temporary" solution, etc.
Here is my idea - using 1/8" or 3/16" thick plexiglass - for our large picture windows (56 x 62) - set the plexiglass in a bead of clear silicone (?) around all 4 sides between the interior white vinyl frame of the window; then face the outside edge with a wood trim painted to match the jamb and casing.
Some of my questions are - how much to allow for contraction/expansion of the plexiglass (MOST of my windows face south)? Is this a good use of 100% silicone? What is the best thickness of plexiglass when it gets to 56 x 62? (The cost increases exponentially with the thicker product.)
These will be a "permanent" for the most part.
My understanding of plexiglass is that it has a much lower transfer of both cold and heat when used on the interior, so "feels" less cold than glass and far less condensation.
For the operating sides of the pictures - I'm thinking of "framing" the plexiglass by using wood trim on both sides, using 1/2" on the back, and maybe screen moulding on the front. (This will give me a total of a 1" air space between the glass and the plexiglass.) Then face the edge of the frame with some type of compression strip for a removable "pressure-mount", and fitting this into the same opening as the screen uses.
What would work best for this? (I would like this to be white, but longevity and an effective seal are more important.)
I think this would also work for double hung windows.
I am willing to try several prototypes to get this right. To complete this project I will need to make these for 11 double hung, 12 casements, 16 large picture, 3 large slider, and 7 medium slider windows.
I appreciate any expertise and advise!:boat:

 

[Windows on Wash]

What is the rationale for the storm window? Energy Loss or Sound mitigation.

 

[JamesRW]

What is the rationale for the storm window? Energy Loss or Sound mitigation.

Energy Loss

 

[SeniorSitizen]

Before reaching too deep into your pockets I'd recommend doing a test on one window with a less expensive product like Visqueen and tape to determine how much or if any condensation forms because of moist gas and the window pane surface possibly being below dew point temperature.

 

[JamesRW]

Before reaching too deep into your pockets I'd recommend doing a test on one window with a less expensive product like Visqueen and tape to determine how much or if any condensation forms because of moist gas and the window pane surface possibly being below dew point temperature.

Ok, I'm not sure what I'm looking for - so far, I have not noticed any condensation on any of the south facing windows and only a small amount on the smaller double hung windows - all of which are on the north side.
My plan is to increase the overall comfort in the entire house while reducing heating costs (natural gas), which are certain to increase!
We barely notice winds from the north or northwest, even up to 30 mph.
However, even a mild breeze from the south, SE or SW during the winter chills the house. When it gets up to 15 mph or more, it's like the windows are cracked open! (The south side of the house faces the lake, and is mostly windows.)

 

[SeniorSitizen]

Those windows are great for the solar gain but as you've found there is also several linear feet for air infiltration that you are attempting to prevent.

The reason I mention a test window is that once you put a material inside to stop air infiltration that same material insulates the glass pane from the room air temperature which in some instances can cause the original glass to reach dew point temperature and form condensation. Even drapes and blinds can act similar keeping room temperature away from window panes.

You may not see condensation during the day, especially with sunshine, but early morning is often a good test or when the gal in the kitchen has the tea kettle going full blast so to speak.

 

[Windows on Wash]

Are the existing windows double pane?

 

[JamesRW]

Are the existing windows double pane?

Yes, they are.

 

[JamesRW]

We put double glazed interior storm windows in our home a couple of years ago, our existing windows were only 4 years old but it was cold near them. The interior storms really did the trick, we couldn't be happier. These windows are manufactured using an perfectly clear film that has a 3/8" dead air space between the 2 layers of film. They look very nice and we didn't need tools to install or remove them in the spring. There was some condensation on my windows on extremely cold days but after installing these that problem was solved also. I just ordered more of these for my office. We bought ours from a company in Wisconsin called ....................I like their product and the price but the double glazing was the real selling point. Ad Removed
Tom

I have looked at these and a sample of their prices. Not sure I want to deal with a thin film that can be punctured on these large windows. Most of them are at a level that maximizes the view - which the grandchildren love year round. We have (5), ages 3 and under right now, and God willingly, there will be that many more! Telling them to "stay away from the window" is not an option.arty:

 

[Windows on Wash]

Yes, they are.

That being the case, are you certain that the windows are your primary energy loss?

There are usually a whole host of other locations to address beyond double pane windows and putting a storm on them may not improve the total R-Value as much as you are hoping for while they will impede the look.

 

[drtbk4ever]

Where are you located James?

We have triple pane windows on our house and Fairviews comment is quite valid. When the temps drop, we get a little condensation on all windows but especially on windows where the blinds are pulled down. So much so we have to wipe them with a towel when we lift the blinds. We try to keep our humidity inside the home high because of the wood floors and we can get some cold temperatures.

I wonder how much of the cold drafts you are experiencing are from the double pane glass as opposed to air flow infiltrating around the windows.

Oops, forgot to add that I wonder if condensation between the double pane and storm glass is possible when it get extra cold.

 

[JamesRW]

That being the case, are you certain that the windows are your primary energy loss?

There are usually a whole host of other locations to address beyond double pane windows and putting a storm on them may not improve the total R-Value as much as you are hoping for while they will impede the look.

We can probably have the utility company come and do an energy audit and have them take a picture with an infrared camera to know that for sure. The house was built in 1965, but all the windows were replaced in 2004, as well as the house was wrapped, then insulation and vinyl siding.
In the process of remodeling, I am removing the interior trim, adding foam and/or fiberglass all around the windows, as well as caulking all jambs before repainting, etc. The top floor is complete, and I think it will take another year before all the windows are done that way.
Another part of the remodel will be a complete a new front entry door system, a new entrance door from garage to the house. There are two other entry doors lakeside, plus a patio door (which may need replacing).
The attic has as much insulation as it can hold.

 

[Windows on Wash]

If you have gone to that extent already, perhaps and interior storm is the next course of action.

We have had success with an interior manufacturer by the name of Quanta Panel out of PA. Might want to give them a ring.

 

[JamesRW]

Where are you located James?

We have triple pane windows on our house and Fairviews comment is quite valid. When the temps drop, we get a little condensation on all windows but especially on windows where the blinds are pulled down. So much so we have to wipe them with a towel when we lift the blinds. We try to keep our humidity inside the home high because of the wood floors and we can get some cold temperatures.

I wonder how much of the cold drafts you are experiencing are from the double pane glass as opposed to air flow infiltrating around the windows.

Oops, forgot to add that I wonder if condensation between the double pane and storm glass is possible when it get extra cold.

We are in Minnesota - just north of the cities.

 

[carpdad]

You have a mix of windows. Casement windows let least air in, then double hung, and side sliders are known for being drafty. It is all about how the weather strip is used. For the future renovations, consider all casement and french door replacements. For what you have, first check the weatherstrip on your windows, and with canned smoke, check for draft. Only the sliders may need what you are proposing.

Not all double pane glazing are same. It is possible your windows are double pane, but only dry air in between. This doesn't do the job as well, and you may be feeling the draft created indoor side of the windows, not air infiltration.

With canned smoke, check around the window trim, around recessed lights (if you have them), around outlet/switch covers, around base molding. Having insulation done and house wrapped do not mean that points of air infiltration were taken care of. Without gutting the interior, blown in, dense pack cellulose gives the best value for air/insulation.

Plexi glass is expensive, and will not stay clear. Just cleaning the plastic will scratch it and dull it over the years.

If you have hot air furnace, cold spots in areas or between cycles could feel like draft.

 

[Windows on Wash]

Not all double pane glazing are same. It is possible your windows are double pane, but only dry air in between. This doesn't do the job as well, and you may be feeling the draft created indoor side of the windows, not air infiltration.

With canned smoke, check around the window trim, around recessed lights (if you have them), around outlet/switch covers, around base molding. Having insulation done and house wrapped do not mean that points of air infiltration were taken care of. Without gutting the interior, blown in, dense pack cellulose gives the best value for air/insulation.

Plexi glass is expensive, and will not stay clear. Just cleaning the plastic will scratch it and dull it over the years.

If you have hot air furnace, cold spots in areas or between cycles could feel like draft.

Good ideas.

The movement of air around the glass is convection and while argon does help slow energy loss, it won't be that much of an improvement.

You other ideas are good as well.