Embodiments herein relate to fenestrations, such as windows and doors, exhibiting coastal impact performance. In a first aspect, an impact-resistant fenestration unit can be included having a frame assembly including a sill, a head jamb, and two opposed side jambs. A bottom sash can be included having a bottom rail, a check rail, and two opposed stiles. A first corner key can be configured to engage the bottom sash at a first lower corner. The first corner key can include a support arm extending in a first direction onto or into a first stile of the two opposed stiles. A first reinforcement member disposed on or within the first stile. The first reinforcement member can include a first end and a second end. The first end can overlap a portion of the support arm of the first corner key. Other embodiments are also included herein.