Can I build 11' x 5.5' loft with 2x2x8 beam and 2x4 joist?

I have looked at a lot of span tables and calculators and am not sure if I can safely build this loft. It is in a garage and will need to bear the weight of two or three people and a build-in desk hanging off the wall. The ceiling is pitched, and clearance underneath is important. To maximize usable height underneath can I get away with a double 2x8 beam at 11 feet, with 2x4 joists (at 12'oc if needed) or do I need to do 2x6 joists? 2x6 ledger will be bolted to 2x6 studs, 4x4 beams anchored into concrete. Joists will be hung off hangers on both sides. 3/4" ply will be glued and screwed into joists.

Are these reasonable, safe plans? Will there be too much bounce on the 2x4 joists at 5'2" span?

Is the double 2x8 enough for a 11 foot span?

• Okay I will use 2x6 joists. Is the 11 foot span of double 2x8 going to give me enough strength? I would hate to have to go to a 2x10 because of the loss of height. Jun 24, 2014 at 15:51
• If you have a 2x8 around the parameter, why are you using 2x6 for the floor joists? From your plans it looks like you are already 8" deep so why not make each joist 2x8? Jun 24, 2014 at 16:21
• @auujay: I will be using the underneath area for storage so maximizing height is important, even the slight difference between 2x8 and 2x6 (although not as great as 2x4 based on my original question). Jun 24, 2014 at 17:13

You will likely experience some bounce using a 2x4 joist even when on 12" centers. I would suggest 2x6 on 12" centers for a nice solid platform floor.

With only a 5'6" width of the platform I think you will have tight work area up there considering a desk on the wall. If the desk is on the long wall I say you have a non-starter situation. If the desk is on the short wall then maybe it is usable but do add a safety railing to the open edge so you do not accidentally fall off. A six foot drop could be downright painful.

• There will be railings around the perimeter - I left them out of the drawing to simplify it. The desk will run along the long wall. Before I came up with the dimensions I did measure out a desk and work area but I will confirm that 5'6" is enough room to work on. Perhaps dummy it up and see if it is actually workable. I could expand it to 6' to add another 6". The desk is going to have a computer and writing area on it. Jun 24, 2014 at 15:53
• 24" deep desk at 27" height gives 3'6" for a chair. Not a lot but still usable - alternative is no office. Do you think 6" would make a big difference? Anything greater than that and it encroaches on usable floor space. Jun 24, 2014 at 17:15
• @Steven - I have three additional comments. A decent work surface is at least 30" wide. Secondly the 6' head clearance is going to feel confining and almost unusable for some folks. Lastly, you mentioned that there would be 2 - 3 people up there at a time. All these make me suggest that you may want to rethink your design idea. Jun 25, 2014 at 3:34
• @Michael_Karas - you say 30" wide, do you mean 30" deep? 6' ceiling height does not include 12" of open rafters, 16" oc. I had hoped that it would add to the sensation of headroom, not to mention clerestory windows and skylights which I failed to add to the diagram. Your point of 2 to 3 people is valid. Likely 1 person will spend much time there with a second or third to review documents once in awhile. I will have to work with my wife and see if we can find this space usable or not. I can lower the platform to give more headroom, but I cannot extend into the main garage any further. Jun 25, 2014 at 6:16
• @Steven - Yeah. I meant 30" surface space out from the wall. Jun 25, 2014 at 10:19