Install replacement window while keeping new construction window in place

key1cc

I recently purchased a new construction home that came with single hung non-loE, no argon windows with u-value of 0.49. I live in Princeton, NJ. The inside window sills have 3-5 inches of available space around the entire perimeter of the window.

Is there anything wrong with leaving the new construction windows in place and simply adding double hung replacement windows in the sill space on the interior? Isn't this like having expensive storm windows?

Any reason why I should not have two windows back to back with 1-2 inches of air space between them?

Thanks in advance for any feedback.

Key1

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HomeSealed

There are a million reasons why this is a terrible idea, not the least of which is that it would void any warranty.

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key1cc

How about naming a few....
Anybody?

I dont see a difference to installing an interior storm window.

Any support or warnings would be appreciated.


Key1

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gotogregg

Hey Key1cc,

It would be more energy efficient, but also would be a waste of time and money. That would be like paying for a new car but only getting the motor. The windows would be hard to open. The heat trapped in between the new window and the old window would cause the seals to fail and you would have constant condensation on the panes.

It seems easier to install the replacement windows as they are intended to be installed. Take out the old sashes and put the new window in their place. Better yet, if it's a new house you could just get new sashes from the company that made the windows and save even more money. I hope this helps. What are your reasons for wanting to try that? With energy efficient sashes you wouldn't need storm windows at all.-Gregg

"In the land of the blind the one eyed man is king." Tom Waits? Misery is the river of world?

key1cc

Thanks for the feedback.
The windows are in the walkout basement...so they are full size. Efficiency for these windows is a close second driver. The primary driver is security. The window locations back to woods and are a prime target for burglars. The replacement window I am looking at is the American craftsman 9500 impact window with laminated glass.

It is my understanding that you only get the heat build up if the outside window has lowE...and it does'nt. It's just clear glass.

A few questions...why would the windows be hard to open and there is a couple inches of space between them?

Would'nt interior storm windows have the same issue with condensation?

Thanks for all the candid feedback.

Key1

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In the land of the blind....the man with one eye is king....

jankencanada

Hey! Please keep this discussion going. I've just installed four small "Energy Efficient basement windows" while leaving the original "storm windows " in place.

Have not noticed any problems as yet, & like the outside appearance. Ken.

Tangelo

[quote=key1cc;615960]Thanks for the feedback.
The windows are in the walkout basement...so they are full size. Efficiency for these windows is a close second driver. The primary driver is security. The window locations back to woods and are a prime target for burglars. The replacement window I am looking at is the American craftsman 9500 impact window with laminated glass.

It is my understanding that you only get the heat build up if the outside window has lowE...and it doesn't. It's just clear glass.

A few questions...why would the windows be hard to open and there is a couple inches of space between them?

If you had a single hung window, then placed a double hung window in front of it on the inside, you would have to lower the top sash of the new window in order to unlock the sash of the old window to ventilation.

Cleaning the glass would be a PITA, not sure if this double window idea would violate any building codes. If you want to keep your warranty, you should contact the manufacture and ask, otherwise you may on your own if something should come up.

key1cc

My inside window is double hung so I can lower, raise, or tilt either sash easily. That should allow access for any required cleaning or to unlock the outer window.
The local building inspector was here the other day for another reason and I asked about the window idea. He said as long as I do not reduce the opening below 5 square feet or require any special tools or key to open it...then i am fine and don't even need a permit.

Thanks for writing and please keep them coming....whether in support of or against, I'd like to here all viewpoints.
Key1

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In the land of the blind....the man with one eye is king....

key1cc

Ok I have some more info on my insane or brilliant idea


The link below shows an airtight inside storm window that is available with or without low E sold by a prominant door&window company. I would think they would have the same problems being mentioned since it is an inside window being installed without removing the outside window.....

http://www.larsondoors.com/storm_win...sider_windows/
Key

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key1cc

The video at the link in my previous post indicates the interior window reduces the regular windows U value by up to 50%!
If that's true, this is a lower cost way to get very efficient.

C.

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In the land of the blind....the man with one eye is king....