2x4's spanning 12'

[ForceFed70]

Bulding a small 12x12 mezanine in the garage.

It will hold some shelving and will be used for light storage. Will only have 5'2" of headroom up there.

To mazimize headroom below the mezanine, I'd like to use 2x4's for the floor joists at 16" OC. I would frame the perimeter with double 2x6's.

Do you think I can get away with using 2x4's for this? I don't really care about bounce in the floor as it's only a storage area.

 

[5lima30]

I would go with 2"x6" for a 12' span with 16" OC. For that size you are not talking about much $ difference. Years from now I think you will not regret going with 2"x6" joists IMHO.

 

[ForceFed70]

I would go with 2"x6" for a 12' span with 16" OC. For that size you are not talking about much $ difference. Years from now I think you will not regret going with 2"x6" joists IMHO.

It not the $$ I'm trying to save, it's the headroom below. If I use 2x6's I will have 6' headroom, if I use 2x4's I will have 6'2". I'm 5'10 and I think that extra 2" will make a big difference in how it feels when standing below.

 

[ForceFed70]

Maybe switching to 12" OC would be a good compromise.

 

[willymakeit]

It will sag . Rule of thumb is 2X4 will span 6' , 2X6 = 8'.

 

[bad_idea]

i built a 8'x10' shed with 2x4s for floor joists with the perimeter made of 2x6s. then supported it in the 4 corners on cinder blocks. within 6 months the shed had sagged enough that i couldn't get the doors open. 2x4s aren't good for much of a load.

considering the difference in head clearance vs. the load capacity, i would probably go with 2x8s. not concerned about bounce, just sag.

 

[blm77]

They are using 2x4 for building a decks, so why not? Just make some extra support

 

[Steevo]

It will sag . Rule of thumb is 2X4 will span 6' , 2X6 = 8'.

This ^^^

 

[rquackenbush]

They are using 2x4 for building a decks, so why not? Just make some extra support

Who is?

 

[bob15]

Use 2x8's or don't bother building it, as it will sag.

Use the following: http://www.awc.org/calculators/span/calc/timbercalcstyle.asp

With a 20 pound dead load, max span for a 2x4 is 5 feet.

Another site: http://www.awc.org/technical/spantables/tutorial.html


bob

 

[Kurzhaar]

We used 2x12 16 OC when we added the 12'x48' loft to oru barn. There is absolutetly NO way we'd attempt to use 2x4's, they just don't have the load bearing strength.

Jim

 

[KEH]

If you seriously want to save the 2" of head room, get flat steel stock 3" wide cut the length of the 2 x 4, 12 ' I think you said. Steel about 1/16 will be thick enough IMO. Drill holes for pan head(I think that's the proper name) at he top and bottom of the steel about 1' apart. Get the wood screws no longer than 1 1/2 " long. I don't remember the number size but if they are 1/8" in diameter they should be strong enough, if in doubt go larger. Install these on ever 2 x 4 and i will be surprised if it sags.

KEH

 

[K'ledgeBldr]

Maybe switching to 12" OC would be a good compromise.

Yeah, it's a good compromise IF you break the span in half. Clear spanning 12' with 2X4 is just plain insane. Why risk the life of yourself or others with something that is totally inadequate. The perception of weight is always miss judged- and it's usually the wrong way!
Generally, most 2X4's are going to be SPF (Spruce, Pine/Fir) and will need to be at least #2 or stud grade. If you truly keep the live load to a minimum (30) and push the dead load to 20- you could conservatively span 7' 12" o/c.

We all hope that a level mind prevails in this quest.
I'm sure you can see the consensus for your question.

 

[Crawfish]

If headroom below is that important, maybe you should give up 2" of headroom above (5' vs. 5'2") and use 2x6.

 

[bczygan]

Need more info. Why 12x12? What does the surrounding structure consist of? What exactly will be stored? Will you need to walk around on the mezzanine? Will the space below be open or have a wall under it? How will you access the mezzanine?

 

[805gregg]

2x6 will span about 11' on 16" centers. Or increase the center to 24" and double the 2x6''s

 

[nehog]

Also consider using 4x4s?

 

[K72nova]

I'm currently building a loft in my shop as well and when I made my decision for headspace vs what size lumber to use I decided that I would spend 95% of my time under the loft so I raised it and used 2x8's for joist's and 2x10 for the ledger to be safe and this is for an 8x8 loft. This is just my input but I'd rather have that little bit more head room below and lose some up top as well as being safe. Mine will primarily be used for storage so I don't require too much height up there.

 

[tcianci]

I agree that the 2x4 construction will sag but those who are worried about the thing crashing down have not spent much time working with wood. Your loft will sag, groan creak and otherwise communicate it's problems to you in no uncertain terms before it fails. I agree that your headroom is important, but you would do well to increase the framing lumber to 2x6 on 12" centers with blocking or cross bridging between the joists at the half span point. The blocking or bridging will distribute point loads across several joists better than plywood or OSB alone. You will be giving up 2" of storage space if you keep your headroom where you want it but you will also be avoiding a retro-fit of the structure down the road.

 

[blkhonda1991]

ATLEAST 2x6 is what id use especially if you are storing things up there, 12x12 can wind up with a decent amount of **** stored up there

 

[ForceFed70]

Thanks guys, decided to go with 2x6 joists.