Barn building OT

I am putting a loft in the shed for all of the stuff that is in the way, nails, screws, bolts, tires. What I need to know is what can I get away with for stringers for the floor(The weight per sq ft won t be bad)What I am thinking is three 2X4s screwed together as a T on 24 inch centers, the span will be 9 ft. I am using pallet rack as a main frame on each end. Tell me what is wrong or right.

(2) 2x4s spiked together will gain you nothing when running them horizontal for a floor joist . Use nothing less than 2x6 at 16" centers . Doing it right will not be one of those I wish I would've done it right the first time deals . HTH ! God bless

Calculate what the weights that will be on your loft deck and see if this helps.
floor joist load calculator

I'd sooner use one 2x8 on 24" centers or a 2x6 on 16" centers. Shouldn't cost any more that three 2x4s and it would be much stronger and have less deflection under a load. Even if the stuff has little weight you have to think of your own weight while you're up there putting stuff in and out, unless it is more like a shelf that you would not be standing on yourself.
Zach

I was told 1" of 2x per foot of run=8' span would be a 2x8. Over building it will not be disappointing!

504, You aren't real clear as to what you are putting the loft in. If we are talking about one of those stock sheds from Home Depot, where you will only be putting a few boxes of nails or screws on, and you will be reaching them as opposed to standing on the deck, it might be fine, yet you walking around on the deck will bring the live load above what a 2x4 with a 24" spacing and a 9' span will support.

Most of today's lumber is crap compared to the quality and strength of lumber 30 years ago. A stud grade 2X4 should never be used as a floor joist. For your application, 2x6's spaced 16" are minimum. If you plan to store hardware or heavy stuff, you'd better go to 2X8's (16" OC). The floor joists in a house are usually figured to carry a load of 50#/sq ft. You can easily exceed that by storing hardware, and not very much of it either.

I use to build houses.

Paul in MN

I have salvaged 2x4s and 2x6s will cost cash. I will try to explain this(a camera would be easier!) I have three sets of rack set with 9 ft between them, the bottom and the very top will be regular shelving and in between I am building the loft(16 ft tall building) I will have a span of 36 inches-9ft.-36 inches-9ft- 36inches. The first span I have 6X6 set on 48in centers(more or less)Then I have all of these pine 2x4s to use. two nailed together and a third nailed across the other two.

If you configure the 2x4s as an I instead of a T you will gain height and therefore get less deflection. Glue and nail the top and bottom members on and it will be fine as long as you control the loading.

If you close the spacing up, you will increase the load limit on the 2x4 joist. You may have to use a 12" OC, but if the 2x4s are free... If you have enough 2x4s, you could consider building cantilever floor joists.

Kevin, 9 foot is quite a ways for a 2x4 but if you double them up you might get away with it for light duty. I built a loft spanning 8 ft with 2x4s and old flooring and throw all my hoods and fuel tanks up there. The total weight would probably scare me.

I"m assuming the 2x4"s are free... As others have stated, probably not the best choice. Just remember, they were graded, milled, and produced to be studs, not joists. To get a feel for the difference, go to a lumber yard and see the difference between a 2x6 stud and a structurally graded 2x6 joist.
But if they were free and you"re proceeding with it, there"s a few simple things to help the system -

1. The I-Beam section as mentioned earlier. Screw/nail AND glue together. Use a good adhesive and not drywall screws. Cabinet screws work better if you"re not using nails.

2. Any scrap rips of plywood? Sandwich those between 2 - 2x4"s and nail together in a staggered pattern. That system is one of my favorite methods to beef up a 2x header in the field when no LVL"s or engineered beams are available. Plywood has the benefit of glued layers of wood with grain running perpendicular each sheet.

3. Glue and ring shank/screw the subfloor to the 2x4 joists. It helps turn the 2x4"s in to little T sections and the pieces start to act together as a system.

Couple notes - adhesive should be a good quality construction adhesive meant for wood to wood bonding. Elmers wood glue probably won"t cut it.
Screws - drywall screws were meant for fastening drywall. If you try, you can probably snap one in half. They were not meant to take a shearing type force that you will have in framing. Try that same action with a cabinet screw or a nail - you won"t snap them.

Last, as others have said, the better method is to use lumber rated for structural use (most 2x8"s and larger at the lumber yard are meant for this). And remember what or who may get under this... any little kids? your dog? Then weigh the costs of the better lumber.

Good luck.

Tony

Two nailed and glued edge-to-edge will be MUCH stronger vertically than two nailed side-to-side and one across the top. Plus it will be much more efficient with the material.

Once the decking is added it'll be solid as a rock.

The guy who used to own my place built a lean-to on the side of the pole barn. 10' span, he used 2x4 rafters spaced 48" on center! Used that translucent green fiberglass stuff for roofing, too...

We get some pretty good snow here, and that fiberglass roofing doesn't let the snow slide. I was sure it was going to collapse.

That lean-to held up for years before I bought the place, and survived my first three winters there. Heck, I even climbed up on it to secure some roofing that came loose in the wind.

Three years ago, I added more 2x4 joists, reducing the spacing to 24". That firmed the structure right up. Then, I re-roofed it with galvanized steel. It's not going anywhere.

Don't discount the strength of the 2x4.

Span makes a huge difference, my lean-to has a 12 ft span, with
2x6 the tables are calling for 12" centres. We have 40-60 psf snow
here.

Jump to 2x8 and it goes to 24" centres.

I had a loft with 15 ft span that I stored styrofoam in, used 6x6.
Sagged 4" mid span just with 6 ft of styrofoam on it.

I don't see anything wrong with it. 'Might just nail and glue 3 2x4's side to side. That will hold a gob of weight. It will take a long time for those to sag. If it falls in....well you'll probably be needing another project anyway. I built a similar bathroom/office in my barn...used two 2x4's for stringers....on 16" centers. 'Pretty much piled high now. Roof hasn't caved in yet.