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Span Table

Maximum Engineering Spans for JJI-Joists


Joist type/
flange

Dead Load up to 1.15kN/m2 [1] Dead Load up to 0.75kN/m2 [2]
Joist spacing (mm) Joist spacing (mm)
300 400 480 600 300 400 480 600
JJI 145A+ 3195 2858 2658 2426 3400 3046 2837 2594
JJI 195A+ 4153 3780 3525 3230 4341 4015 3753 3445
JJI 195B+ 4476 4133 3900 3568 4682 4326 4112 3809
JJI 195C 4654 4295 4079 3758 4870 4496 4272 4010
JJI 195D 5062 4662 4422 4141 5301 4886 4637 4346
JJI 220A+ 4471 4134 3907 3584 4673 4323 4113 3819
JJI 220B+ 4861 4489 4266 4004 5084 4698 4466 4195
JJI 220C 5000 4615 4384 4113 5230 4831 4591 4310
JJI 220D 5396 4973 4719 4421 5649 5210 4946 4638
JJI 235A+ 4643 4294 4084 3780 4853 4490 4272 4018
JJI 235B+ 5042 4657 4426 4156 5273 4873 4633 4352
JJI 235C 5190 4792 4552 4272 5429 5015 4767 4476
JJI 235D 5602 5164 4901 4593 5864 5410 5137 4817
JJI 245A+ 4754 4397 4182 3906 4968 4597 4374 4114
JJI 245B+ 5153 4760 4524 4248 5388 4980 4735 4449
JJI 245C 5313 4905 4660 4374 5557 5134 4879 4582
JJI 245D 5740 5291 5022 4707 6008 5543 5263 4936
JJI 300A+ 5336 4936 4696 4416 5575 5160 4911 4620
JJI 300B+ 5739 5304 5042 4737 6000 5548 5277 4959
JJI 300C 5954 5499 5226 4907 6227 5754 5471 5140
JJI 300D 6459 5957 5655 5302 6759 6238 5925 5559
JJI 350C 6526 6028 5729 5380 6825 6308 5997 5634
JJI 350D 7030 6485 6158 5775 7357 6791 6451 6054
JJI 400C 7106 6563 6237 5857 7431 6867 6529 6134
JJI 400D 7514 6933 6585 6177 7861 7259 6897 6474
JJI 450D 7909 7301 6935 6508 8273 7642 7262 6819

B. Figures in Bold indicate that web stiffeners are required.

  1. The self-weight of a typical compartment floor comprises of 18mm deck, 19mm plasterboard lining, resilient battens, mineral wool, 15mm sub deck, joist self weight, quilt insulation between joists, metal resilient ceiling bars and two layers of 15mm plasterboard ceiling lining. The effect of the dead weight of non-load bearing partitions can be assumed to be included in the design where the self weight of the partitions does not exceed 0.8kN/m run and the self weight of the floor construction does not exceed 0.9kN/m2.
  2. The self-weight of a typical domestic floor comprises of 22mm deck, 15mm plasterboard and joist self weight. The effect of the dead weight of non-load bearing partitions can be assumed to be included in the design where the self weight of the partitions does not exceed 0.8kN/m run and the self weight of the floor construction does not exceed 0.5kN/m2.

The span table above for floor joists is based on the following design criteria.

  • This table serves as a guidance only. For a detailed appraisal contact a JJI-Joist supplier
  • Dead Load 1.15kN/m2 or 0.75kN/m2.
  • Imposed Load 1.5kN/m2 (Domestic floor imposed load).
  • Deflection Limit 0.003 times span or 12mm whichever is lesser.
  • Adequate lateral restraint to the top flange of the joists is assumed to be provided by the floor deck. 18mm chipboard or equivalent for joists at up to 400mm centres and 22mm chipboard for joists at up to 600m centres.
  • The joists are designed using the principles of BS5268: Part 2 2002.
  • Where the load conditions are different to those described above, refer to a JJI-Joist supplier for further assistance.

 

 

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