I don't think you can sub-divide the 3rd bedroom both privately AND cheaply. It might be possible to put in a wall of curtains on a suppor,t like hanging clothes racks or ceiling-mounted curtain rods, cutting between the 2 doors from into and out of 3rd bedroom (to create a triangle-shape 3rd bedroom) to provide visual privacy, but this, or a wall of shoji screens, won't provide auditory privacy.
The space on the wall behind the bathroom next to the window in what is now the 3rd bedroom, but now curtained off, could be used for a small table (maybe one of the "Murphy tables" that fold down from the wall), and folding chairs. Ikea also makes a tiny fold-down table, and you can buy bar-height tables with stools that slide underneath at Target.

I'd hate to be Roomie #3, with no noise/smell barrier while people eat and hang out in the other half of my room. If the bedrooms are spacious enough, you could put a loveseat and coffee table in each room, so that it's more like 3 separate bedsits that share a kitchen and bath.

The simplest solution, however, is to have 2 people in one bedroom (either a low-key couple or casual friends, college-style) and use the living room as social space. It can work well depending on people's schedules and how much of their life is spent outside of home.

I agree with the other posters. There is no good way to partition it off for privacy where it would have sound privacy. The only way, like Ms. Tart mentioned, is to rent to a couple. To be fair as far as the rent split, you might have to give the "new room" to them as an office.

I think under any other arrangement, the tension created would not be worth the savings in rent. Of course, if others have lived in open floor plan lofts with roomies before, it could work. I suspect, however, that the rooms are not quite that large.

Does the kitchen have enough room for bar stools or a cafe table to eat? If you can attach a long board to the wall and have it fold down to sit at, that might eliminate the need to have a dining area in the living room. That might solve a problem if you have two related people or close friends okay with the idea of having to pass through the other room.

Get a handy friend and head down to Home Depot and pick up some cheap pine, a cheap door and some plywood or drywall. Make a frame, clad it, and install the door. It'll cost a few hundred dollars and be a lot of work, but it'll be better in the long run than fiddling about half-heartedly with curtains or room dividers.

Splitting the 2nd bedroom in half, so that each new room gets half of the closet, might be an alternative to the idea of splitting the living room. Then put up a sheer curtain (to let in light) to screen the new bedroom on the left from the small transit space between the door to the living room and the door to the bedroom on the right. That way the 3rd roomie only has her privacy slightly compromised when the 2nd roomie is transiting from living room to bedroom. And you all get a decent sized living room.

Why not try to find a couple for the second bedroom?

As for making the living room more private, you're going to need to hang curtain rods from near the ceiling with full-length curtains and go from the doorway to the second bedroom to the entrance to the living room. For the most privacy, you'll either need a very thick curtain or go with layers so the person can choose their privacy. Whomever gets this room is going to have a much smaller bedroom and is going to want to pay less rent.

As for common spaces, you only will have the foyer and one corner of the living room. You might be able to squeeze a couple chairs or a small two-person dining table without overcrowding it. A chair (maybe two) and ottoman could probably fit into the living room corner that won't be part of the third bedroom.

I would probably put three twin sized beds in the largest bedroom, maybe with privacy curtains around each, make the second bedroom an office/gaming area and leave the living room as is.

In my experience, people who choose to live with roommates spend more time in common/communal areas and to have more of that would be preferable to gigantic isolated bedrooms (especially if they are very social and like to have parties and other friends over).

It is hard to tell if putting up a wall in the LR to createa BR is feasible since you don't give dimensions. The room has to be as least large enough along one wall to fit a bed.

If you have never lived with a couple and know if works for you I would not recommend it, there is less democracy in a 2 on 1 scenario (your apt or not).

Without measurements it is hard to say if this would work, but I would make the converted 3rd room L shaped (with the door on the short side near the closet-and door should open out so takes up less of the room's space). Since would be the smallest room with the smallest closet would make their rent share less. Then in the small common area get a drop-leaf table (I have the Ikea NORDEN table, which is quite narrow when not in use, and has handy storage drawers, so maximizes usefullness of space it takes up), a small bench (with cushion and pillows) for the opposite wall that also doubles as table seating when pulled alongside the table and a few chairs. It depends on how many people you need seating for, as you could always get stackable chairs and keep in the corner by the window and unstack as necessary or two cosier chairs and do one near the bench and on in that corner by the table.

Also, I would reccomend a tall wardrobe for the foyer, either as a concession to third bedroom or for use of everyone. That way space is utilized and entry is made useful, and so all linens and in-season outwear doesn't need to be kept in individual rooms. OR you could always hang bike hooks as three people worth of bikes leaning against a wall is messy, and takes up much less space, and opens up floor.

In case you cannot tell I LOVE organizing and maximizing space, my friends and family keep telling me to go into business :) So feel free to send me your email if you want a sketch or to talk in more detail.

ps - I agree with BLANDWAGON, that you use a frame and put hardwalls in, makes roommates more likely to take space with actual walls. Depending on where you live, can usually find people who do this for apartments on craigslist, so have expertise and they will be in and out, with you paying for supplies and their time.

I like the idea of putting a coffee table and a couple chairs in each room. Is there room for a bar and a couple stools in the kitchen, even if it's a tiny one in front of the window?

It is a litle hard to know how big the space is without the dimension, but this idea might help. Consider buying a group of bookcases to make a "wall". The shelves would face into what is the living room/3rd bedroom and create storage for books, baskets with bins to store clothes. I would leave space at the end furthest away from the second bedroom to create a doorway. Since the back of the bookcases will be the outside or hallway, they could be painted (blackboard paint might be fun) or wall papered or mirrored. A gallery of photos could also be put there or the whole thing could be covered with a blown up mural (How about a pic of all the roommates). Ikea's Billy bookcases would be a good choice since they have many style options and they also have an extender that might go all the way to the ceiling, creating even more privacy, depending on the ceiling height. They are also reasonably priced. I'd be sure to screw the cabinets together, much like kitchen cabinets to increase their stability. Again, you can't tell by the drawing how large a bed could fit in the space. To make a door, you could use a curtain rod with a curtain to cover the opening or a bifold or sliding door that can be purchased from Home Depot or Lowes or maybe even a local hardware store. Depending on how much space is left on the corridor side of the bookcases, you might be able to put a narrow table. No mater what, the 3rd roommate should pay less, just to be fair. Maybe that person has a 2nd or 3rd shift job, so they are there during the day while everyone else is at work--just a thought!

in most areas, it is illegal to make sleeping or primary rooms w/out windows, and it looks like the l/r has only one window, on one side yet. whatever gets erected must look temporary or owner can be fined & you can be evicted. personality of roommate 3 will dictate success as much as any wall, too

True story: In college I had a similar floor plan and we divided a two bedroom place into three very cheaply. My dad pressure fitted 2x4's with a door frame as well to divide the room. This used very few nails and didn't damage the walls. Next, we purchased, cut to fit and painted cheap paneling that we placed on the front and back of the frame. Last, we hung a door. It cost less than $200 in materials and only took one day. The only bit of advice I could give is that I wish we would have invested in a little bit of soundproofing material for in between the paneling. Otherwise, it would have been perfect.

Oh, my goodness! If I'm not mistaken I lived in this very apartment when I first came to DC (and judging by the fact you had to draw your own floorplan, and what I infer is the location, I think it's a pretty good bet).

Here's the good news: we also converted it into a 3-bedroom, and overall it worked well for a year. I was that unfortunate roommate with the converted bedroom, but I made it work well by using a white shoji folding screen to give some privacy and flexibility, as well as maximize the light coming into the room from the window. I bought my screen + 2-3 extension pieces at Oriental Furniture; you can check that out here: http://www.orientalfurniture.com/room-dividers.html

It really wasn't a terrible setup. I had a ton of space (queen bed, 2 nightstands, bookshelves, desk, and dresser and chair in the nook by the window. I would angle the screen at a diagonal from the corner of the wall by the door to bedroom 2 to create a passage to that room from the foyer door. I was a student and my roommate worked, so our schedules actually worked out well that I only had to put up the screen when I wanted privacy or was going to bed before she was. Otherwise I would just leave the screen folded back and enjoy the entire room. Admittedly, it did get a little old having her come through my room (particularly if she was having loud friends over in her room), but again, really not bad.

As for common space- we stuck a couch, chair, coffee table, and TV and printer in the foyer and it worked fine for common space for us. The couch was along the long wall by the front door, the tv and printer on a small bookshelf between the bathroom and closet door, and the small chair in that bit of wallspace between bedroom 1 and the kitchen. A bit close/awkward, but we did fine with that. If you don't need a TV, you can add another small chair and make it a more communal space.

To our surprise, we found we were able to fit a regular table and chairs from ikea in the kitchen. We pushed it all the way back to almost the window, giving a bit more space around the sink. I don't remember what model we bought, but it would be useful for you to take some measurements and see. You could also easily put in a long, thin, bar-like table with chairs or stools.

Hope that helps! Honestly, the toughest thing for us was having three women to one bathroom. But it's a nice building and a lovely location; enjoy!