Would it break if you loaded it at 100 psf? SP glulam, select a 3-1/8x11” beam requiring a 3.0” bearing length. Assuming that your members are beams, American Institute of Timber Construction (AITC) Technical Note 19 address your  question directly. I'm primarily interested in 3x6 studs at 16" on center and 20ft lengths. Duration of load factor is not allowed however. If there is are any questions about anything else, then you should contact your supplier or an engineer. Piffin had this variation on the I-joist option: “What I would do is to add a 2×4 to the top and bottom of each joist, using glue and structural screws to convert each joist into an I-joist in place,” Piffin writes. Add in an appropriate factor of safety, in the U.S. typically this is 1.4 for dead 2x4 beam load capacity 5-by-5. Garth Dreger PE - AZ Phoenix area The theory a contractor explained to me is that it creates a hinge point at the weakest part of the joist, right in the center of it's length. My single Garage hasn't been Used for a car for years. White Paper - Test Reuse Across MIL SIL HIL in a Development Workflow, eBook - How to Remove 5 Obstacles to Digital Transformation, White Paper - Digital Twins and Immersive Technologies in the Energy Industry, eBook - The Future of Product Development is Here. 2 2×6 over a 16-ft. span can carry 10 psf while a 2×8 will carry 20 psf. I start by fastening a 2x12 ledger board on each side of the storage area. we should "think out-side the box" with this one..go outside your building and determine where it would be really neat to have an access door (or panel) ABOVE the in question 2x6's..1;this is where you will slide in what ever you need to strenthen the joists from ABOVE ..glue lams,whatever..I would also block the 2x6's below the area where the lam would be placed to give you a good purchase area to tie them(2x6's and lam(s) together)..and 2;now you have a good access area Outside you building to handle longer stock that,as we all know,is not fun to handle with tools and benches in our work space. 2 2×6 over a 16-ft. span can carry 10 psf while a 2×8 will carry 20 psf. Girder Example. 1. a load must be supported at both ends, so using partial reinforcements with no posts is not good. Replace a Rotten Lally – A proper footing and post add floor support that will never fail again. Click to enlarge, Another view of the shop For a residential load where I live, I believe the load tables state a minimum of a 2x12 would be needed for a 16' span. Yes, just pure vertical capacity. where I've stored various amounts of dimensional lumber. I have heard, but not read or verified with an engineer, that it is actually better to NOT have the plywood filler seam EVER land right in the middle of the joist. Already a member? Their job it to make sure that an assembly is 2-3 times stronger than it needs to be. So now I will confess that I used 2x10's in my job and spanned 20'. I agree bonding & screwing a 2x to the bottom of each joist might be sufficient, but you could halve the effective span by hanging the joists along the centerline under the ridge with gusset plates and vertical 2x4's. Screw the metal joist to the existing wood ceiling joist and to each plate and you have very effectively reduced the load deflection of any stored attic loads for little cost. “If so, go buy 4 pieces of 9 1/4 inch [laminated venner lumber],” JAlden writes. Micro-Adjust Deck-Baluster Spacing for an Eye-Deceiving Layout, Podcast 301: Stick vs. Post Frame, Upside-Down Clapboards, and Caulking Cedar Shingles, Plus, get an extra 20% off with code GIFT20, Simple Way to Make Old Walls Straight and Plumb, Expert insights on techniques and principles. Promoting, selling, recruiting, coursework and thesis posting is forbidden. Sistering the two together means a load-carrying capacity of 30 psf. It seems to me that I read somewhere that you can reinforce the ceiling joists in such a way as to give them the strength of floor joists. Probably not as long as the joist didn't have a big knot midspan. “No sistering or modification of I-joists to the existing situation,” he says. My Son was in a Power Wheelchair so I Built a New Workbench out of the Old Bases and Built a Wheelchair Ramp in MY Garage. 6. if you want to increase your bearing capacity you can do this - take four 10 ton coil springs from a junk yard, install them over the corners of your building inside where the load bearing is the greatest, and build the entire load bearing platform over an X brace of 4x8s. This allowed me to use some 15/32" osb I had on hand for the floor of the storage area. You could install an UPSET beam down the center in the attic. In this white paper learn how a standards-based, systematic, and automated generative MDD/XIL workflow helps automotive engineers develop their production ECU Verification & Validation (V&V) suites early during software modeling, and reuse them throughout the overall systems engineering project.