This is such a excellent question. Your picture really spells things out nicely. In the future i really want to do something similar, but i can't imagine doing w/out the header. Maybe go with a steel frame window

Love the idea of opening the whole front of your home.... but it will be difficult for a licensed professional to offer such delicate advice over the internet. I recommend working with a local engineer/architect to achieve your look safely. Good luck and post up your final design!

@rgk, get over yourself! What "delicate advice" is needed to answer if you know a company?
"So my question is this: Are there any windows on the market that don't require a header? Is there anyone out there that builds frames that are strong enough to support the load of a roof (e.g. 10,000 lbs/ft)?"

Peter, here's a site you may want to look into http://www.fgdglass.com/products/commercial/spandrel-glass

I found it by searching "store front window frames". Might still need a header though for your load requirements

Some store front windows i seen in my experience are actually 3 or panes laminated together to get a thickness of 1 inch or more. I recommend tempered glass for your project

Rgk gave very good advice. The short answer is no. More over most design like this do have headers and supports they add dropped ceiling and tray work to mask the dropped header/supports. The design's mentioned is called curtain glass walls . The support structure like a header is designed to the structure. The design will take in to place stuctural exposure of that particular face. ie: snow load if applicable up lift if in huricane areas etc. This will need a beam and point loads of some kind. In the end the structures again mentioned all had one thing in common they had an engineer or arcitect of record.
Good luck

You may also check out Old Castle Glass or Kawneer for the curtainwall application. You will definitely need to use tempered glass. Call a locale glazing company in your area that installs storefronts and they can help you out..

Fred S, sorry my response was not to your liking. To extrapolate, 'delicate advice' = Architect 'a' tells peterborissow to use window 'x', peterborissow takes a sawzall to the house and installs the windows ... later finds himself with the roof as his bed cover. peterborissow calls his insurance company and says Architect 'a', on Houzz, told me I can put this window in...

That's why I said most licensed design professionals would not give this type of advice over the net. I am not an architect so this advice would NOT benefit me in any way, so hard to get over 'myself' since I'm not referring to 'myself'. Just want peterborissow to do it safely.

Others here have just googled the load bearing windows, another solution might be to visit your local window supplier. But as stated by Flagship Construction it would be more of a 'glazed structural wall' (curtain wall)... which would probably run more money than just adding, say a beam and losing a few inches or incorporating something into the structure like Design on the Square mentioned... again all can be worked out, in my opinion, onsite much better..

HI -- My husband use to be in the window business and he said if you put in a six inch steel beam header you can make it work . Big windows like that will have to be tempered glass . What you are wanting to do is more in a commercial window category . Best to ask a commercial window company . Your city building permit office might have a condition or two about this being done on your house .

Thank you rgkDESIGNS, Inc. for making what is probably the only truly helpful comment here.

The discussion is to replace a bearing and shear wall with a structural product. Pretty much every US state LAW dictates a local licensed design professional be providing the advice on how to do that. Best go find one for this project.

As for product solutions, structural glazing systems are about the only way to do this but whatever you do with them will inevitably create point loads in the structure that were not there in the bearing wall and you'll still need a structural engineer to sort out the cantilevered beams in the floor back to the foundation wall and if you still have the structural shear capacity you need.

Another possible solution is to create a flush beam up in the attic to carry the roof loads set back from the window wall directly above the foundation wall where you have more depth and let the new windows and the remaining roof simply be outriggers from there. That would take all the load off the exterior bearing wall you want to replace with windows. It would also allow you to do it all with standard products and lumber. The drawback is you'd need to find a few points inside where you could add new bearing posts to support the new flush beam in the attic. And you still need to deal with shear. And you'd still need a local engineer.

Find a local engineer to help you with this. It is not simply a product solution unless the product supplier provides engineering services.

I agree with RGK , contact a structural engineer so he can do a load calculation so the window frame can be properly designed and installed.
You don't want this to happen to you as indicated in pictures bellow... this people got answers on the internet, then hired a contractor from Craig's list who also said its ok and he made a bigger opening, but he installed improper sized header not realizing that roof and portion of the second floor was bearing on that header, and after the first snow storm the header split, causing a 4" drop.

Thanks to everyone who has commented so far. I really appreciate all the feedback! To be clear, I have already consulted several architects and builders. They have shared pretty much the same advise I've read here. What I want to know is whether there are products on the market that perhaps my local builders and architects haven't seen before. For example, I can envisage a simple steel window frame that is only 4'x8' that could support 1000lbs/ft. The headers and footers of such a frame would be relatively small, maybe a couple inches. If I married up 5 such frames, I would be able to span the 18-20 feet I am looking for.

So again, are there any products like this in the market today? If not, I'll have to do what all the builders are telling me. Or better yet, maybe I need to find someone to fabricate something for me.

There is products which can work, but it will cost you a good penny and I doubt you will be happy with the outcome. You will not gain any value for the amount of money you will spend on it.
IMO would be better if you change the roof design over the area and transfer point loads to a different location... then build a gable roof and make a 2 story all glass with an open raised ceiling inside...than it will be a blow out of a design and it will make your house look real good, not to mention the 10k or more that you spend on that window alone, you can redo the whole roof.
If you make all glass on the house as you have it now, it will look like a subways car (excuse me for being bold) If you like I can do a sketch for you tomorrow and show you what I mean, since its already late.

Where are you getting your loads from? First of all, you have to account for lateral forces in removing all of that wall, so you would have to put in a combination of moment frames and shear walls. Simpson does sell shear walls. There is no residential window product that has the capabilities that you are looking for. Curtain wall can be used, but it is very expensive, and may not follow the energy code requirements for your area. To do all of that glass, you may have to super insulate the remaining walls. Also, please consider if you are in a hurricane or high wind area, the local codes would require that the window not only be tempered, but also debris resistant during a storm.

"Otherwise, consider a small pane down low of tempered and regular up above. "

FYI: The right elevation geometry can lift the safety glazing requirements of IBC 2406 from the lower pane as well.

Sorry, rgk, my objection is only to the canned answer to go somewhere else to get ideas on a forum designed to do just that, and assuming to know what I will and won't discuss here. "Hey, did you know about this product" is not a violation of any sacred oath.
We seem to be talking about two separate things. The statement; "Or better yet, maybe I need to find someone to fabricate something for me." DEFINITELY needs a local structural engineer, given the design parameters you are looking for, but they don't have magic powers. They follow the same principles and math as everyone else. All you will end up with is a one-of-a-kind, very expensive experiment that most buyers in the future will run away from. Engineers may be responsible for a lot of successes, but they are also responsible for all the failures in a case like you are proposing. Apollo 13 vs. Space Shuttle Columbia for example.
As for your original question,
Most systems like insulated concrete forms, non-traditional wall systems, engineered beams, and trusses are sold WITH an engineer stamp and designed by the manufacturer, often for your specific project. In general, a system should not need any 'extra' consideration from a second engineer or architect on the job site. (for a single family dwelling in the US) If it did, then it becomes an on-site fabrication and not the system you were asking to find in the original post. Note; stipulation/objection "(b) requires additional engineering and effort." You are probably not going to find a viable 'system' solution in this case. Mostly because you are trying to defy too many basic design principles.
You have gotten a good deal of incite and advice here that goes beyond just "hire an architect". That is what I like to see :) None of it is a substitute for someone local, but hopefully helps in the process.
Moving the beam over the foundation and up into the attic is part of a possible solution, but with a shallow pitched roof, a beam with a span of usable length probably won't fit. One solution is to leave the ceiling in place and raise that half of the roof up to accommodate the beam. This type of construction and design using conventional materials and techniques can probably be handled by a competent design/build company. If the roof is built with engineered trusses, you will need to get the truss company's engineer involved if possible. At the point you decide to raise the roof, you will find that several other design options open up that may appeal to you and cost about the same. As others have said, this is only part of what needs to be considered when taking out that much wall. Of course, that is why you were looking for a system. One thing I would add is that if you put the beam over the foundation and cantilever the roof, the cantilevered part is subject to deflection caused by loading of the main part of the roof with snow or other factors. The design will have to eliminate or accommodate the fulcrum. The 1/8" of movement at the window header would play havoc with the ability to make the house energy efficient to say the least.

IBC Hazardous locations requiring safety glazing
2406.4.4 Glazing in guards and railings.
Glazing in guards and railings, including structural baluster panels and nonstructural in-fill panels, regardless of area or height above a walking surface shall be considered a hazardous location.

1013.2.1 Glazing.
Where glass is used to provide a guard or as a portion of the guard system, the guard shall also comply with Section 2407. Where the glazing provided does not meet the strength and attachment requirements of Section 1607.8, complying guards shall also be located along glazed sides of open-sided walking surfaces.

1013.4 Opening limitations.
Required guards shall not have openings which allow passage of a sphere 4 inches (102 mm) in diameter from the walking surface to the required guard height.

When I gave you a suggestion yesterday, this is what I had in mind. Here is a view from inside and outside. Of course wall and ceiling modification will have to be made inside and all the point loads loads must be transferred accordingly, and also you can do a smaller A over the front door, etc. But like others have mentioned, the only way to do this is raising a ceiling and you should contact a local Architect to calculate the loads, and you will need specialty windows made, and you will need a good GC or a contractor whose specialty is framing, because this has to be done right.
Good luck, I hope it helps

Fred S - no problem, will chalk it up to a misunderstanding .. Although your knowledge of THE Sacred Oath worries me! :)

GN great concept.

But just to be devils advocate and still try to salvage the 'cheaper' subway car look and going with the less expensive (beam/post) setup .. just maybe... excuse the simplicity and crudeness of my elevation please.. just a quick 5 minute thing..