My design studio recently expanded, and we are wanting to put in a huge screen in the center of the room, that can be motorized/retracted into the ceiling. It needs to be about 8' tall, and about 11'+ wide. It also needs to be double sided, as we need to project from both sides. I've searched google for about 30 minutes, no dice.
If you actually intend to use two projectors projecting onto the front and back sides of the same retractable screen with viewers on each side of the screen, you have two options...
1) Use two layers of one-sided front projection screen fabric, placed back-to-back. If you go with a fabric that is 100% opaque (such as Stewart Filmscreen Firehawk G4) then you might be able to do this with only those two layers. If the screen fabric is not 100% opaque then you will want to add a layer of black fabric between the two reflective layers to prevent light bleed-thru from the other side. I would consult with an expert to ensure that the 3 sandwiched layers of fabric will still be flexible enough to be rolled up without kinking or if there is an alternative method of retraction that would work in your room.
2) Consult a screen manufacturer (such as Stewart Filmscreen) and ask if a single layer fabric can be custom ordered that has the same reflective treatment on both sides and 100% opacity.
I would try to get a quote for both options as I have no clue which option will be more affordable or if option #2 is even possible.
A third option that would likely be cheaper than either of the above would be to use a single projector and a 50/50 screen (such as Lumiflex 50/50). This screen allows approx 50% of the light to pass thru the screen while reflecting the other 50% of the light. So it acts as front and rear projection at the same time. The main drawback of this option is that the image will be reversed on one side of the screen. This isn't that big of a deal if you material has no text, but would obviously be an issue if it does as the text would be mirrored on one side or the other. Also, this requires a nearly completely dark room, whereas the above options can tolerate some ambient light.