Permissible Clear Spans for Domestic Floor Joists (to BS 5268-7.1)

Imposed load
1.5 kN/m²
Strength class

Note: Our floor joist span tables are based on loadings given in the newer, amended version of BS 6399-1. This means that some values are slightly more conservative than span tables from other sources if those do not include the amended guidance. See the notes below the span tables for details.

  • Find the column for your dead load and spacing, and the row for your timber size to find the permissible clear span in metres.
  • Click on a span to generate a full calculation (you can adjust the exact span).
  • This span table is to the format and methodology given in BS 5268-7.1.
  • These spans were calculated using our floor joist calculation engine.
  • These span tables are the equivalent of other industry-standard span tables and are calculated to the same standards.
  • This table uses commonly available UK regularised timber depths.
  • Read the notes at the bottom of the table for assumptions, references and related standards.
Back BACK FLOOR JOIST CALCULATOR
C16
Dead load per square metre (in kN/m²) supported by joists
Not more than 0.25 More than 0.25 but not more than 0.5 More than 0.5 but not more than 1.25
Centre-to-centre spacing of joists (in mm)
Joist size
Width × depth (mm)
400 450 600 400 450 600 400 450 600
Permissible clear span (metres)
38 × 95 1.275 1.268 1.246 1.225 1.213 1.162 1.109 1.089 0.994
38 × 120 1.933 1.919 1.868 1.828 1.805 1.704 1.604 1.569 1.406
38 × 145 2.681 2.656 2.488 2.497 2.458 2.285 2.133 2.077 1.832
38 × 170 3.357 3.325 2.887 3.175 3.116 2.701 2.681 2.603 2.266
38 × 195 3.962 3.780 3.281 3.751 3.541 3.071 3.207 3.024 2.618
38 × 220 4.462 4.228 3.672 4.196 3.961 3.437 3.588 3.385 2.931
44 × 95 1.466 1.458 1.432 1.402 1.388 1.326 1.258 1.234 1.122
44 × 120 2.196 2.184 2.130 2.080 2.052 1.928 1.807 1.764 1.574
44 × 145 2.879 2.859 2.676 2.739 2.708 2.504 2.387 2.322 2.037
44 × 170 3.596 3.493 3.104 3.394 3.340 2.906 2.986 2.862 2.479
44 × 195 4.159 4.000 3.528 3.979 3.805 3.303 3.448 3.253 2.818
44 × 220 4.674 4.505 3.946 4.482 4.255 3.695 3.857 3.640 3.155
47 × 95 1.561 1.551 1.522 1.489 1.473 1.406 1.330 1.303 1.184
47 × 120 2.269 2.257 2.221 2.176 2.155 2.036 1.904 1.858 1.654
47 × 145 2.971 2.951 2.765 2.824 2.792 2.588 2.509 2.439 2.136
47 × 170 3.707 3.571 3.207 3.496 3.415 3.002 3.077 2.957 2.562
47 × 195 4.251 4.089 3.644 4.067 3.911 3.412 3.562 3.361 2.913
47 × 220 4.750 4.605 4.075 4.581 4.394 3.818 3.984 3.760 3.261
63 × 95 1.872 1.863 1.838 1.806 1.791 1.750 1.657 1.632 1.487
63 × 120 2.616 2.600 2.534 2.499 2.473 2.402 2.250 2.210 2.045
63 × 145 3.407 3.363 3.057 3.226 3.187 2.922 2.859 2.803 2.555
63 × 170 4.086 3.934 3.577 3.913 3.765 3.421 3.479 3.386 2.965
63 × 195 4.670 4.501 4.096 4.478 4.309 3.918 4.033 3.878 3.370
63 × 220 5.100 4.957 4.613 4.939 4.799 4.405 4.542 4.340 3.770
72 × 120 2.786 2.769 2.650 2.657 2.629 2.534 2.385 2.342 2.230
72 × 145 3.620 3.514 3.196 3.421 3.363 3.057 3.025 2.964 2.730
72 × 170 4.267 4.108 3.739 4.086 3.934 3.577 3.674 3.541 3.167
72 × 195 4.822 4.688 4.280 4.670 4.501 4.096 4.215 4.054 3.599
72 × 220 5.265 5.119 4.775 5.100 4.957 4.613 4.721 4.566 4.025
ALS/CLS
38 × 89 1.133 1.127 1.109 1.092 1.083 1.040 0.997 0.980 0.898
38 × 114 1.766 1.754 1.712 1.677 1.657 1.569 1.482 1.451 1.305
38 × 140 2.526 2.503 2.408 2.359 2.323 2.166 2.025 1.974 1.746
38 × 184 3.741 3.582 3.108 3.529 3.355 2.909 2.993 2.865 2.480
89 × 184 4.860 4.727 4.333 4.709 4.553 4.148 4.268 4.106 3.733
89 × 235 5.803 5.647 5.275 5.626 5.472 5.108 5.216 5.070 4.724