Loft/Mezzanine design help

[zr52002]

Hey all. I've got a 15x30 garage condo unit, and I want to build a 15x12 mezzanine in the back portion of it. Somewhere to park some storage, as well as air compressor, dust collector, that sorts of thing. I'm trying to figure out the best way to construct this so I can have something a little more firm to take to contractors to find somebody to actually do it. (I have to get this permitted and done by a licensed contractor).

It's a garage condo in a much larger steel framed building, so this thing has to be self-supporting. I've seen a few other lofts in the condo complex and construction methods seem to be all over the map so figured I'd start here.

For no larger than it is, and for how gross a lot of lumber I'm seeing lately, I'm kind of inclined to have it built with I-joists and LVL beams. Should be a little more likely to stay flat in unconditioned space as well. I'm kinda inclined to go to 12" joist spacing, as well, because it'll only cost me 3 more joists and I'm even less likely to ever overload it.

Sizing/spacing for joists cross the 15' dimension is straightforward to work out. What I'm not clear on is how to hold those up. Probably 12' LVL's on top of 6x6 posts in the corners. But where I'm really unsure of is what method of bracing the posts to both the beams and the end joists to give the whole structure racking resistance. There just doesn't seem to be a lot of information about building this kind of thing, and building it well.

thanks!

 

[SMOKEYBEAR]

I built something simular in my 18x30 steel building. Mine is 18'x6'. It's basically the width of the building with a depth equal to the distance of the first vertical support away from the back corners. I used 6x6 posts in the corner, and some 4x4's across the back wall. The 18' span is 3- 2x10's over glued and over screwed, some 2x4 pieces notched to fit between the corner posts for some "racking" stability. The 6x6's and 4x4 posts are through bolted to the steel posts. I do not have any posts on the front 18' span other than the 6x6s at the corners. I framed the joists using metal hangers, decked it with 1/2" plywood. It's plenty strong for want I store up there, and if need be I could add posts on the front 18' span and make it significantly sturdier.

 

[firebirdparts]

I agree that's basically what you need. I bet a licensed person would likely buy an engineered beam for the front, and that's fine.

In traditional framing lumber construction, the dimensions would be very similar to that in a house: supports front and back (the beams) would be on 8 foot centers (i.e. about half of 15 feet) and the span of 12' is perfectly normal with boring old framing lumber. It's worth it to you to take out that front middle support and so let the contractor do that however he chooses to.

If you absolutely can't tie on to the building, then I think a little corner bracing will do. The building would sure be a nice thing to have ahold of.

 

[zr52002]

I agree that's basically what you need. I bet a licensed person would likely buy an engineered beam for the front, and that's fine.

Why run an engineered beam the long dimension when you can run joists over the long spam with short beams on each end?

If you absolutely can't tie on to the building, then I think a little corner bracing will do. The building would sure be a nice thing to have ahold of.

It's a clear span building so my "back wall" is the middle of the building, there's nothing to attach to.

 

[Craig Balzer]

These guys have reasonably priced options: https://www.mezzaninesonline.com/