Wood framed ramps are by far the most common in the industry. Wood is relatively easy to mill and assemble. Like other products wood also has limitations with the type of lumber used and the methods of fabrication. All lumber used for exterior structures should be wolmanized or pressure treated preferably SYP with a .40 retention factor. Fasteners should be galvanized or stainless steel screws or nuts and bolts.

Ramp surfaces of plywood, treated or untreated are problematic. Plywood is made of thin layers of wood glued together. When this laminate is bent the concave aspect of compressed, jamming the outter layer causing buckeling and delamination rendering it unsafe for use as a skating surface. 

Many failing plywood ramp surfaces are resurfaced with steel or a phenolic fiber laminate. Masonite is not suitable for exterior use due to the water absorption properties of the product.

Fastening ramp surfaces to wood based structures is usually done with countersunk bugle head galvanized screws, also known as deck screws. These screws have a high twist and a narrow shank that can snap off at the head or work thier way out exposing the screw head above the ramp surface. These conditions must be corrected immediately.

Wood is alright, but is by far not a permanent ramp structure.