12x16 floor joist span - how far is too far?

[Hellfighter]

I plan to build a 12x16 wood frame workshop. The foundation will be built with2x8's on 12 inch centers. The frame will rest on concrete block pads that are roughly 4 inches thick and 12x12 in size. Can I span the joists all the way across (12 feet) or do I need support in the middle? Or Should I place 3 rows of 4x6's on the concrete pads and build my frame on top.

 

[aubrey601]

Edit

 

[Trey T]

12' is minimal but if you give additional 20-30% factor of safety, it's not adequate. Therefore, you would need center support if you want to stick with your plan. Otherwise, there's different way of strengthening it.

Assumptions:

1. #2 southern pine (typical @ HD)
2. Live Load @ 40psf and Dead Load @ 10psf
3. 12" spacing
4. incised lumbers


Span Calculator for Wood

 

[Old Moparz]

My living room is 14' x 18' & had 2"x8" joists spanning the 14' dimension. When you walked through the room you were able to feel the floor move & watch the lamp on the table shake. I have since added a triple 2"x6" girder in the center to stop the flex & it's much better. The room has nowhere near the load in it that a shop would have, but I would never, ever use a 2"x8" for a floor joist with a span like that. When I built my garage the second floor is all 2"x10" joists that span 12' or less. Walking up there is rock solid.

Which is easier for you to do, raise the height of the workshop to use a 2"x10" or add supports in the middle of the 2"x8" joists?

 

[pattenp]

If using SYP the 2X8's on 12" centers easily provides a 40lb SF live load with a span of 12'. Unless you are setting a 500lb cabinet saw and a 500lb planer in the middle of the floor then you'll be okay with the 12' span. To be sure to not have a bouncy floor the center support would be a good thing.

 

[gpalmer77]

I'm dealing with a similar span right now, plans call for double 2x8s on 16 centers, doug fir.

 

[Hellfighter]

Thanks, for all replies. I will use whatever pressure treated lumber is available at Lowe's or HD. I will probably add the center support now. I will only save a few bucks by not doing it.

 

[pattenp]

Thanks, for all replies. I will use whatever pressure treated lumber is available at Lowe's or HD. I will probably add the center support now. I will only save a few bucks by not doing it.

That's a smart thing to do. It's better to do it than to be pissed later because you've got a bouncy floor.

 

[ishiboo]

I love clear spans... I would run a 11" TGI and keep the span open.

EDIT: I mean 11" TGIs as the joists, not a single TGI for a center beam.

 

[theoldwizard1]

Thanks, for all replies. I will use whatever pressure treated lumber is available at Lowe's or HD. I will probably add the center support now. I will only save a few bucks by not doing it.

+1 !

 

[camarotoolman]

PT 2x12s on 16" centers. Thats what most houses have.

 

[964haus]

I recently built a 10x16 shed using a skid foundation. I used 3 skids under 2x6 joists w/3/4 ply on top. Really feels solid....

m.

 

[rslaback]

I love clear spans... I would run a 11" TGI and keep the span open.

EDIT: I mean 11" TGIs as the joists, not a single TGI for a center beam.

It's outside. I haven't yet seen a ground contact TJI but I suppose it is possible they exist.