34 Pa. Code § 21.63
(a) The following woods may be substituted for spruce in required spruce sizes
| Red alder | Alnus rubra, rhombifolia. |
| Alaska cedar | Chamaecyparis nootkatensis. |
| Red Cypress | Taxodium distichum. |
| White cypress | Taxodium distichum. |
| Yellow cypress | Taxodium distichum. |
| Douglas fir (Rocky Mountain region) | Pseudotsuga taxifolia. |
| Douglas fir (Inland Empire) | Pseudotsuga taxifolia. |
| Noble fir | Abies nobilis. |
| Silver fir | Abies amabilia. |
| White fir | Abies concolor, grandis. |
| Black gum | Myssa sylvatica. |
| Red gum | Liquidambar styraciflua. |
| Hackberry | Celtis occidentalis, laevigata. |
| Holly | Ilex opaca. |
| Magnolia | Magnolia grandiflora. |
| Soft maple | Acer saccharinum. |
| Idaho white pine | Pinus monticola. |
| Yellow poplar | Liriodendron tulipifera. |
| Redwood | Sequoia sempervirens. |
| Eastern spruce | Picea glauca, rubra. |
| Sitka Spruce | Picea sitchensis. |
| Sycamore | Platanus occidentalis. |
| Tupelo | Myssa aquatica. |
This section cited in 34 Pa. Code § 21.21 (relating to wood side rails); 34 Pa. Code § 21.32 (relating to side rails); 34 Pa. Code § 21.40 (relating to step ladders); and 34 Pa. Code § 21.65 (relating to wood for ladder use).