Timber Span Tables
The information below is for guidance use only! Please be advised that a structural engineer should be saught fo advice on structural loading and capacities, please note that these tables cannot be used as proof of span adequacies
Strutting
| Joist Span (m) | Rows of Strutting Between Supports |
|---|
| x < 2.5 | None |
| 2.5 < x > 4.5 | 1 at mid span |
| 4.5 < x | 2 at one third span positions |
Floor Joists
This table shows C16 Grade, maximum timber spans in (meters) for a dead load of 0.25 - 0.50 kN/m2. For higher grade timbers or different loadings then I guess you will have to look somewhere else.
Size of Joist (mm) | Spacing of Joists (mm) |
|---|
| Breadth | Depth | 400 | 450 | 600 |
| 38 | 97 | 1.7 | 1.5 | 1.2 |
| 38 | 120 | 2.3 | 2.1 | 1.7 |
| 38 | 145 | 2.8 | 2.6 | 2.3 |
| 38 | 170 | 3.3 | 3.1 | 2.7 |
| 38 | 195 | 3.7 | 3.5 | 3.0 |
| 38 | 220 | 4.2 | 3.9 | 3.4 |
| |
| 47 | 97 | 1.9 | 1.8 | 1.4 |
| 47 | 120 | 2.5 | 2.4 | 2.0 |
| 47 | 145 | 3.0 | 2.9 | 2.5 |
| 47 | 170 | 3.5 | 3.4 | 3.0 |
| 47 | 195 | 4.0 | 3.9 | 3.4 |
| 47 | 220 | 4.5 | 4.3 | 3.8 |
| |
| 63 | 97 | 2.2 | 2.0 | 1.8 |
| 63 | 120 | 2.7 | 2.6 | 2.4 |
| 63 | 145 | 3.3 | 3.2 | 2.9 |
| 63 | 170 | 3.9 | 3.7 | 3.4 |
| 63 | 195 | 4.4 | 4.3 | 3.9 |
| 63 | 220 | 4.9 | 4.8 | 4.4 |
| |
| 75 | 120 | 2.9 | 2.8 | 2.5 |
| 75 | 145 | 3.5 | 3.4 | 3.1 |
| 75 | 170 | 4.1 | 3.9 | 3.6 |
| 75 | 195 | 4.7 | 4.5 | 4.1 |
| 75 | 220 | 5.1 | 5.0 | 4.6 |
Ceiling Joists
This table shows C16 Grade, maximum timber spans in (meters) for a dead load of not more than 0.25 kN/m2. For higher grade timbers or different loadings then I guess you will have to look somewhere else.
Size of Joist (mm) | Spacing of Joists (mm) |
|---|
| Breadth | Depth | 400 | 450 | 600 |
| 38 | 72 | 1.1 | 1.1 | 1.1 |
| 38 | 97 | 1.7 | 1.7 | 1.6 |
| 38 | 120 | 2.3 | 2.2 | 2.2 |
| 38 | 145 | 2.9 | 2.9 | 2.8 |
| 38 | 170 | 3.6 | 3.6 | 3.4 |
| 38 | 195 | 4.3 | 4.2 | 4.0 |
| 38 | 220 | 5.0 | 4.9 | 4.6 |
| |
| 47 | 72 | 1.2 | 1.2 | 1.2 |
| 47 | 97 | 1.9 | 1.9 | 1.8 |
| 47 | 120 | 2.5 | 2.5 | 2.4 |
| 47 | 145 | 3.2 | 3.2 | 3.0 |
| 47 | 170 | 4.0 | 3.9 | 3.7 |
| 47 | 195 | 4.7 | 4.6 | 4.4 |
| 47 | 220 | 5.4 | 5.3 | 5.0 |
Rafters
This table shows C16 Grade, maximum timber spans in (meters) for a dead load of 0.50 - 0.75 kN/m2 and an imposed load of 0.75 kN/m2 For higher grade timbers or different loadings then I guess you will have to look somewhere else.
| 15o < xo < 22.5o | | 22.5o < xo < 30o | | 30o < xo < 40o |
|---|
Size of Rafter (mm) | Spacing of Rafters (mm) | Size of Rafter (mm) | Spacing of Rafters (mm) | Size of Rafter (mm) | Spacing of Rafters (mm) |
|---|
| Breadth | Depth | 400 | 450 | 600 | Breadth | Depth | 400 | 450 | 600 | Breadth | Depth | 400 | 450 | 600 |
| 38 | 100 | 1.9 | 1.8 | 1.7 | 38 | 100 | 2.0 | 1.9 | 1.8 | 38 | 100 | 2.1 | 2.0 | 1.9 |
| 38 | 125 | 2.6 | 2.5 | 2.3 | 38 | 125 | 2.7 | 2.6 | 2.4 | 38 | 125 | 2.8 | 2.7 | 2.5 |
| 38 | 150 | 3.2 | 3.1 | 2.8 | 38 | 150 | 3.3 | 3.2 | 2.9 | 38 | 150 | 3.4 | 3.3 | 3.0 |
| | | | | | | | | | | | | | |
| 47 | 100 | 2.2 | 2.2 | 2.0 | 47 | 100 | 2.3 | 2.2 | 2.1 | 47 | 100 | 2.4 | 2.3 | 2.1 |
| 47 | 125 | 2.9 | 2.8 | 2.5 | 47 | 125 | 3.0 | 2.8 | 2.6 | 47 | 125 | 3.1 | 2.9 | 2.7 |
| 47 | 150 | 3.5 | 3.3 | 3.0 | 47 | 150 | 3.6 | 3.4 | 3.1 | 47 | 150 | 2.7 | 3.5 | 3.2 |