First and foremost I'm a drywaller not a framer but I have a buddy who wants us to do a job for his welding shop. the shop has a 16 foot lid but the corner office has a wood framed ceiling at eight. He wants us to put up an office next to the preexisting office space from one wall to the next wall meaning three walls for this office are finished and all that needs framed are the lid and a front facing wall with a door way. What would be your best advice on framing in the lid. The width of the lid will be 12 ft accross from the preexisting office wall to the preexisting shop wall. He wants the office to be identical in height as well and wants some form of decking on top to support about 12 lbs. a square ft.
Your advice would be greatly appreciated.
Is the "lid",a ceiling? You would frame the ceiling the same as you would a house. For get the 12 lb load thing, frame it for the same load you would any floor. You could use, "I" joist to span the 12 feet. Just have the size spec'ed out . Some lumber yards have that service.