34 Pa. Code § 21.61
The following woods may not be more than 10% smaller than spruce in each cross section dimension
| White ash | Fraxinus americana, biltmoreana, pennsylvanica lanceolata, pennsylvanica, quadrangulata. |
| Beech | Fagus grandifolia. |
| Birch | Betula lenta, lutea, nigra. |
| Douglas fir (dense) | Pseudotsuga taxifolia. |
| Rock elm | Ulmus racemosa. |
| Hickory | Hicoria ovata, laciniosa, alba, glabra, ovalisi. |
| Ironwood | Ostrya virginiana. |
| Black locust | Robinia pseudacacia. |
| Honey locust | Gleditsia triacanthos. |
| Hard maple | Acer nigrum, saccharum. |
| Red maple | Acer rubrum. |
| Red oak | Quercus borealis maxima, borealis, velutina, shumardii texana, palustris, phellos, laurifolia, rubra, rubra pagodaefolia, nigra, ellipsoidalis, coccinea, marilandica, kelloggii, catesbaei. |
| White oak | Quercus alba, stellata, lyrata, bicolor, muehlenbergii, garryana, prinus, montana, macrocarpa, lobata, virginiana, douglasii, utahensis, emoryi, arizonica, oblongifolia. |
| Osage orange | Toxylon pomiferum. |
| Pecan | Hicoria pecan, cordiformis, cordiformis elongata, myristicaeformis, aquatica. |
| Persimmon | Diospyros virginiana. |
| Southern pine (dense) | Pinus taeda, palustris, serotina, echinata caribaea, rigida, glabra. |
This section cited in 34 Pa. Code § 21.21 (relating to wood side rails); 34 Pa. Code § 21.23 (relating to wood steps); 34 Pa. Code § 21.31 (relating to general); and 34 Pa. Code § 21.65 (relating to wood for ladder use).