The first method you describe in setting the replacement inside the steel jambs is what is called a "Frame Jump".

It is an acceptable method, however, it does not address the large thermal bridge of the steel pan or the dated look of the interior.

I usually recommend that customers remove the entire pan and trim out the window with new jamb extension, interior trim, and exterior trim/capping.

From today's New York Times...including resource names for new casement windows... Just some additional things to consider.

Casement Windows Are Architectsâ New Darling

FOR a long time, mullioned steel casement windows, the gridded kind that swing out like a door, had fallen out of fashion. They leaked badly, and a stiff wind could blow out their panes or knock their hinges askew. Over the years they have been replaced in many buildings by single-pane aluminum casement or double-hung windows.

But now those classic casements are appearing on new apartment buildings with startling regularity, especially in West Chelsea and the West Village, as part of an architectural style that pays tribute to prewar buildings.

In large part, New York has Cary Tamarkin to thank for the return of casements. An architect and developer, Mr. Tamarkin is sometimes referred to as âÂÂthe window guy,â because of the distinctive casement windows in his New York City buildings, including 140 Perry Street, 495 West Street, 397 West 12th Street and, most recently, 456 West 19th Street, a 22-unit 11-story all-duplex building with 5 apartments still for sale, starting at $2.2 million.

As to the reason for using old-fashioned casements, which are typically more expensive than conventional windows, Mr. Tamarkin said, âÂÂItâÂÂs a kind of commitment to a classic Modernism which is rooted in traditions of authenticity.â Most of his projects are in neighborhoods rich with warehouse buildings, he said, so he designed them to âÂÂlive comfortably amid their settings.âÂÂ

Mr. Tamarkin says he uses pricey steel casement windows �" as opposed to aluminum �" because the mullions are slim (âÂÂI donâÂÂt like fat-mullioned windows,â he says) and because the metal shows pockmarks and other signs of use, lending them an old-fashioned character.

His windows are also made the old-fashioned way. âÂÂYouâÂÂve got actual little panes of glass that are painstakingly put in one by one,â he said. âÂÂTheyâÂÂre very subtle details, but the people buying in our buildings are sensitive to the design. Either you donâÂÂt get it and itâÂÂs meaningless to you, or you canâÂÂt live without it.âÂÂ

Jaime Roth is one of those sensitive buyers. She had been looking for an apartment in the West Village when her brother suggested she look at 456 West 19th Street. When she saw the windows, she decided to buy a three-bedroom unit.

âÂÂThe windows were really the reason why I bought that apartment,â she said. âÂÂI like that itâÂÂs new construction but it feels kind of old. ThatâÂÂs what the windows do.âÂÂ

Casement windows are a feature at 200 11th Avenue, where a penthouse is for sale for $17.5 million.

Sara Lopergolo, a partner at Selldorf Architects, which designed the building (Steven Kratchman is the architect...

Don't forget you will need to have a lead test done and if necessary, comply with the lead containments law.

Thank you all for posting. WOW raised an important point. Thermal bridge.
Marks suggestion of ordering the windows to "just fit" inside the steel frame makes sense from the point of not having to saw out the steel frame to install the window. Then, I assume, I would trim the flange to fit inside the concrete blocks and trim and foam the windows to finish.
I will be returning to this post to hear more ideas for sure.
Next summer I will start a new post with pictures as to how I did the project. It should be interesting?
I have replaced the "8 light French Door" windows in the b-rooms last year. Original to the 50's w/no insul glass, no weather strip etc. These were in the two bedrooms on the N end of the house. Boy did the house warm up. I should have chronicled the event. Sorry.

I'm going to hijack this thread..but I am staying on topic :)
We, too, are considering replacing our casement windows. Our house was built in 1980 and has aluminum siding. We are getting ready to put our house on the market. Our biggest fear is that it won't look good or that some how the siding will get damaged and we'd have a whole other mess on our hands.
Is switching from casement to double hung hard or just time consuming? I really feel we need to at least change out the one by the front door -it's a horrible place for a casement and the sash isn't in great shape.
Or do we just cut our losses and not do anything?

The change from casement to DH in your situations would be simple, and no more work than replacement with another casement. There never should have been a casement window in that location.

I totally agree. Whoever thought putting a casement right in the traffic flow was a good idea was an idiot.
So would the process be what WOW recommended above? The one guy we spoke with said replacing with a DH is a little different b/c he said a casement does not have the standard frame?

If your selling you might just want to take your chances and let the next owner deal with it.

It's difficult to tell a non-professional how to install something we can't see. From the OP, he never mentioned a steel pan system, so I'm not sure if he's talking about leaving the steel pan in and installing on top of that - in which case the pan will still transmit cold from the outside to the inside. However, he might be talking about leaving the narrow steel frame of the casement - sometimes these are finned into the block walls, sometimes screwed into a hidden wood frame. If they are finned they can be a nightmare to remove. I can see that if this is the case, and there is no steel pan, that the opening could be lined/framed with 1x6 or 2x6 and then the new window installed in the wooden frame. Then the exterior could be wrapped with aluminum over the old steel frame.

Hope I didn't just confuse the whole issue. Trying to understand what is existing.

If there is indeed a steel pan system, I would definitely remove that by tugging and cutting and get it out. Though I've seen it done with it in, and it is a heck of a lot easier, it isn't really the right way to do it.

onlygirlsmom,

You don't have steel pan window. They were utilized years ago and your home being build in the 80's would not have what the original poster was referring to.

Switching from a casement to a double hung is neither difficult nor overly time consuming.

If you are getting ready to sell the home, I am not sure this modification is a necessity to market the home. Just leave the window closed and being done with it.

I am not home right now. I will take better pictures of the unit when I get home later. I'll also take pictures of the sill. In the end it may be best to just leave it alone.

For what it's worth, here are some good DIY videos on window installation. They don't specifically address your questions, but I found them helpful on a recent project. The page takes a second to load.

Here is a link that might be useful: window installation videos

I'd agree with the comments above in reference to whether or not it is worth it. I would say no if the only reason is because of the poor choice of configuration, but yes if the window is actually in poor condition.