A: Thank you for your question, drck. Because shower bases are typically installed to the studs and the enclosure is installed to finished walls, DreamLine recommends that the shower base be appx. 2" larger in size than the shower enclosure dimensions. In the case of the Unidoor Plus shower enclosure you have referenced, we recommend that your shower base be 32" by 51". Unfortunately, DreamLine does not make a shower base in this size at this time. We invite you to contact our DreamLine Customer Support Team at 866-731-2244 to discuss this further. We can also be reached by sending an email to support@dreamline.com. Our hours of operation are 8am-7pm EST, Monday through Friday and Saturday from 9am-5pm EST. Thank you for considering DreamLine!