Where is the room (attic, basement, etc) and what is above that space?
Speakercraft (and other speaker comanies) make engineered enclosed in-ceiling options. If there is a chance to exchange the current speakers for the enclosed ones, I highly recommend it. Otherwise I would definitely consider an enclosure but I would recommend speaking to Speakercraft for the exact dimensions or whether you should build one. If a speaker has an open back design it is designed that way and building an enclosure too big or small could impact you sound quality.