If you are just starting out, you might want to go to the joist page since we will expand on the house design example introduced there. This site also has information on learning how to read joist tables and a joist calculator. You'll find a beam span calculator towards the bottom of this page. On this page we will explain how to read and design with floor beam span tables. I'll do more investigating of engineered wood and 9'5" clear spans, but it's nice to know I have another option available to me.Designing with Floor Beam Span Tables Part 3 of Residential Structural Design Second, when I sit up in bed, poking my head between the exposed beams, and face forward, then I'll be staring at a beam running directly across my field of view instead of gazing down the length of the beams. (Is a 3.5" ledger board even practical? I've never seen one that narrow.) So, putting a ledger board along the top of these storage walls will effectively remove 3.5" of shelf space at the top of the walls. I can foresee two possible issues with this suggestion, neither of which is a deal breaker.įirst, my plan is to have a wall of storage drawers and shelving on both sides of the bed. According to a floor span calculator I was pointed to, Douglas fir 3.5x3.5 (actual) beams should be able to handle that with up to 22" o.c. Even a king-sized bed would leave me with a clear span that's only about 6.5'. Another option would be to run the joists across the width of the bed. I was fixated on the idea of running the floor joists the width of our 10' trailer (along the length of our bed). Someone at a tiny house forum came up with an outside-the-box (as I defined it) alternative. Much closer to actually being workable.Ī much better FJ could be made by ripping a 1-3/4 x 9-1/4 LVL into two 4" strips and nailing them together to form a (2) 1-3/4 x 4" LVL. If you properly glue and screw 3/4" plywood subfloor to the top, then it is only inadequate by 6%. I did a proper engineering analysis, and a 3.5 x 3.5 SPF #2 (4x4) is INADEQUATE by 72%. Regardless, the Deflect-O-Lator does not check stress, so it is USELESS. That means L/370 or L/380 would be sufficient, but L/182 is twice as much deflection as allowed. L/182 IS TOO MUCH DEFLECTION! You want L/360 deflection or less. Since the maximum deflection for tile is L / 360, and for natural stone is L / 720, your floor is rated for Sheet Vinyl or wood. This translates to a deflection of L / 182. Thank you for using the John Bridge Forums Deflect-O-Latorįor joists that are SYP or Douglas Fir, in good condition, 3.5 inches tall, 3.5 inches wide, 16 inches on center, and 9.5 feet long between supports, the deflection calculated is 0.627 inches. Second of all, your wood section is 3.5" x 3.5", not 4" x 4". Your floor joists will be critical in stress.įirst of all, your span is 9'-5", so the closest chosen span should have been 9.5 ft., not 9 ft. That Deflect-O-Lator floor joist calculator is a joke. Sorry, I'm a little late to this discussion, since it took place late November. Thanks in advance for any help you can offer. But maybe that extra strength is all I need to get me the extra 19" of clear span while still preserving my 2 inches of additional headroom. Instead of being about 250% stronger than a 4x4 beam, it would be only about 150% stronger. I realize that sacrifices lots of strength. Instead of laying a 4圆 SPF beam with the long edge vertical, I could lay the long edge horizontal. Am I wrong? If not, then will any engineered 4x4 beams do the trick?Īnother option I'm considering seems a little silly at first. However, from what I've been able to figure out so far, the extra 19" of clear span in our house rules out your typical 4x4 SPF or Douglas fir beams. The standard width of tiny houses on wheels is 8'6", and 4x4 SPF beams seem to cover their 7'10" clear span okay. These tiny houses are pretty much restricted to 13'6" in height (including trailer), so vertical space is at a premium. It's a tiny house on a trailer, so I want to keep the beam depth to no more than 3-1/2 inches (actual) to maximize headroom. But those companies' span tables treat those beams as beams rather than floor joists. I'm willing to consider engineered wood beams and have seen 4x4 LVL, LSL, and PSL products. I understand living room floors need to handle 40 psf live loads and 10 psf dead loads with L/360 deflection. Common lumber beams locally are Douglas fir and Spruce-Pine-Fir (SPF). My clear span is 9'5", and I'd like the joist spacing to be no less than 16" o.c. Maybe an engineer type, carpenter, or internet sleuth can help me. I'm hoping to use 4x4 (nominal) wood beams as living room floor joists, but none of the online span tables/calculators seem to handle 4x lumber.
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