Housed stringer details
This diagram and chart show engineered unsupported stringer lengths for housed stringers.
In the diagram, brown shows the Ply-Lam housed stringer. Its thickness (W) and depth (D) are adjusted to suit the required unsupported length. In this design, a 5/8 in plywood stringer is added to the Ply-Lam stringer to support the treads and risers.
This is one possible design. Always check unsupported length calculations against your own design.
| Product code | Thickness (W) | Depth (D) | AB code permitted unsupported length |
|---|---|---|---|
| Spruce 2x10, routered to 1 in | 1.5 | 9.25 | 160 |
| PL3 H 10 | 1.125 | 10 | 157 |
| PL3 H 11 | 1.125 | 11 | 171 |
| PL3 H 11.5 | 1.125 | 11.5 | 179 |
| PL3 H 11.75 | 1.125 | 11.75 | 183 |
| PL3 H 14 | 1.125 | 14 | 220 |
| PL3 H 16 | 1.125 | 16 | 251 |
| PL4 H 10 | 1.5 | 10 | 172 |
| PL4 H 11 | 1.5 | 11 | 189 |
| PL4 H 11.5 | 1.5 | 11.5 | 198 |
| PL4 H 11.75 | 1.5 | 11.75 | 202 |
| PL4 H 14 | 1.5 | 14 | 240 |
| PL4 H 16 | 1.5 | 16 | 275 |
| PL6 H 10 | 2.25 | 10 | 205 |
| PL6 H 11 | 2.25 | 11 | 226 |
| PL6 H 11.5 | 2.25 | 11.5 | 236 |
| PL6 H 11.75 | 2.25 | 11.75 | 241 |
| PL6 H 14 | 2.25 | 14 | 286 |
| PL6 H 16 | 2.25 | 16 | 328 |
| PL8 H 10 | 3 | 10 | 217 |
| PL8 H 11 | 3 | 11 | 239 |
| PL8 H 11.5 | 3 | 11.5 | 250 |
| PL8 H 11.75 | 3 | 11.75 | 255 |
| PL8 H 14 | 3 | 14 | 304 |
| PL8 H 16 | 3 | 16 | 345 |
The shaded row is solid spruce, shown for comparison.