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
C24
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 1.608 1.602 1.582 1.557 1.545 1.512 1.437 1.417 1.312
38 × 120 2.262 2.249 2.213 2.168 2.148 2.090 1.965 1.931 1.823
38 × 145 2.962 2.942 2.761 2.815 2.783 2.637 2.511 2.463 2.339
38 × 170 3.698 3.563 3.233 3.487 3.407 3.089 3.068 3.004 2.740
38 × 195 4.243 4.080 3.704 4.059 3.902 3.539 3.633 3.502 3.115
38 × 220 4.744 4.596 4.174 4.572 4.396 3.989 4.108 3.947 3.487
44 × 95 1.733 1.726 1.703 1.675 1.662 1.625 1.541 1.519 1.459
44 × 120 2.430 2.416 2.375 2.326 2.303 2.239 2.100 2.064 1.969
44 × 145 3.175 3.153 2.903 3.012 2.976 2.774 2.677 2.625 2.485
44 × 170 3.890 3.742 3.398 3.722 3.579 3.248 3.265 3.196 2.911
44 × 195 4.453 4.284 3.892 4.262 4.098 3.721 3.832 3.682 3.336
44 × 220 4.918 4.778 4.385 4.759 4.616 4.192 4.317 4.149 3.752
47 × 95 1.792 1.784 1.760 1.730 1.717 1.678 1.590 1.566 1.503
47 × 120 2.509 2.494 2.452 2.399 2.375 2.308 2.164 2.126 2.027
47 × 145 3.275 3.251 2.968 3.103 3.066 2.837 2.755 2.701 2.543
47 × 170 3.975 3.824 3.474 3.804 3.659 3.321 3.357 3.285 2.978
47 × 195 4.550 4.378 3.979 4.355 4.189 3.805 3.918 3.765 3.413
47 × 220 4.997 4.856 4.483 4.837 4.699 4.287 4.414 4.242 3.846
63 × 95 2.071 2.061 2.029 1.993 1.976 1.927 1.820 1.791 1.715
63 × 120 2.884 2.865 2.715 2.747 2.717 2.596 2.461 2.416 2.299
63 × 145 3.740 3.600 3.274 3.534 3.445 3.132 3.118 3.055 2.812
63 × 170 4.372 4.209 3.831 4.188 4.030 3.665 3.772 3.628 3.293
63 × 195 4.910 4.773 4.385 4.755 4.612 4.196 4.319 4.154 3.772
63 × 220 5.361 5.213 4.862 5.193 5.048 4.705 4.807 4.669 4.250
72 × 120 3.068 3.047 2.839 2.917 2.884 2.715 2.606 2.557 2.431
72 × 145 3.905 3.759 3.422 3.740 3.600 3.274 3.295 3.227 2.943
72 × 170 4.562 4.394 4.003 4.372 4.209 3.831 3.942 3.792 3.445
72 × 195 5.068 4.928 4.581 4.910 4.773 4.385 4.512 4.341 3.946
72 × 220 5.532 5.381 5.023 5.361 5.213 4.862 4.966 4.826 4.445
ALS/CLS
38 × 89 1.460 1.455 1.438 1.417 1.407 1.379 1.314 1.297 1.192
38 × 114 2.100 2.089 2.057 2.017 2.000 1.949 1.836 1.806 1.699
38 × 140 2.819 2.800 2.667 2.684 2.654 2.547 2.400 2.355 2.239
38 × 184 4.006 3.853 3.497 3.833 3.684 3.341 3.384 3.306 2.950
89 × 184 5.106 4.967 4.634 4.949 4.813 4.439 4.565 4.395 3.999
89 × 235 6.093 5.931 5.545 5.909 5.750 5.371 5.484 5.332 4.971