Some engineered wood fiber (EWF) surfaces on playgrounds are soft and uneven, which creates difficulties for those who use mobility aids, such as wheelchairs and walkers. The outdoor field testing reported in this study is part of an effort to stabilize EWF to improve accessibility. The concept is to mix a binder with the upper surface of EWF to create a stiff (firm) and scuff-resistant (stable) composite overlayer. Latex, silicone, and polyurethane binders were evaluated on small plots during a 6-month outdoor trial in Wisconsin. Tests were performed at regular intervals to‍?provide a quantitative measure of accessibility. After 6 months of exposure, all the surfaces passed the existing specifications for impact attenuation of playground surfaces. Exposure changed impact performance of all systems except the unsurfaced (without an additive) EWF. The latex and‍?polyurethane stabilizers consistently met accessibility requirements. One polyurethane formulation produced a hard brittle shell that became even harder with exposure and age, which might increase the injury rate for falls on that surface. The silicone system failed to maintain integrity adequately‍?during the rain/dry cycles of the test. Moisture measurements indicate that the bonded surfaces retard drying of the underlying EWF, which may have long-term implications for the rate of decay for these systems.