I know it is common knowledge that one should using different cutting boards for meat and vegetables (cross contamination), but should you also use a different cutting board for raw/cooked meat? Or at least clean the raw meat cutting board first? My roommate thinks the different meat/vegetable cutting board is absolute, so as long as you cut meat on one board you are safe. But I'm pretty sure a surface where raw meat was on can't be safe can it? Thanks.
You can use the same board (I often do), but you must wash it in hot, soapy water in-between. Usually there is plenty of time to do this while the meat is cooking. Because bacteria grows exponentially, I'd recommend washing the board soon, even if you aren't going to reuse it, to prevent accidental cross-contamination.
If you're using one meat board, you should also wash it between different kinds of meat. For example, pork and chicken typically have different bacteria risks and different cooking temperatures because of those bacteria. If you cross contaminate, then safely cooked pork may still have a risk of salmonella.
And, of course, you should wash your knives, spatulas, tongs, etc between handling uncooked and cooked meats.
You do not need separate cutting boards, technically you only need one board
After using a board you must mechanically scrub it for hygiene and flavour cross contamination reasons
If the board is not properly washed between raw and cooked foods, it does not matter that it is a "separate" board, you will be causing a hygiene situation
Wash boards by using running water (hot or cold) and a stiff scrubbing brush. Hot water and a little dish soap helps with fats and oils on the board
Lightly dry the board with a clean towel and store upright in a sunlight place. Light helps fully dry the board, and the UV light will promote bacterial breakdown
Obviously having multiple boards makes life easier, but while using them you must track which one is which, and after some time (< hour) you should be cleaning and recycling them. Always clean a board back to the point it can be used for anything again
In a large commercial kitchen the rules will be different, mainly for time expediency reasons
Technically, TDF is absolutely right, but in household situations, separate boards are a must. We're not always as hygienic as we should be, and separate boards for raw meat and cooked meat are essential. Remembering which is which is important, obviously - I use glass for raw meat and nothing else so I don't get them mixed up. If your roommate thinks about it, cutting raw and cooked meats on the same board is equivalent to storing raw meat on top of cooked meat in the refrigerator, which I hope isn't something he/she thinks is okay.