Login or register (free and only takes a few minutes) to participate in this question.
You will also have access to many other tools and opportunities designed for those who have language-related jobs (or are passionate about them). Participation is free and the site has a strict confidentiality policy.
Explanation: "auskoffern" is not a German term, to my knowledge. It probably was borrowed from the engliosh "coffering", which means "to make water-tight by means of a coffer dam". Since gypsum plaster board would hardly qualify as a water-tight sealant, I think they just mean that steel supports are "lined" with this material.
Explanation: Couldn't find "abkoffern" in any of my construction related references, and a Google search yielded only one hit, and that one was irrelevant.
I'd say that words' reasoning makes a lot of sense, however, when I see the word "lined", I think of something that's on the inside (i.e. ausgekleidet), and Gipskartonplatten could hardly be on the inside of a steel beam. Thus my suggestion of encased. Maybe it gives you another option. Good luck.