...from the daily life of a specifier
Primarily it is not constructable. A 1" deep reveal in 5/8" drywall would be at best an expensive detail to construct. At worst having drywall follow the profile cannot be done. Cutting a 1" strip of drywall is not practical.Secondly, triming wall covering in a reveal would be tedious.Thirdly, how would you precisely finish this detail and then insert then moulding?I understand the effect the detailer is after. Unfortunately it shows a lack of understanding of the construction process.
Yes and no. Sub framing could be expensive and tedious, but the drywall can be fabricated with a drywall milling system. http://www.magacon.com/dry-wall-solutions/
First, The detail requires that 1-inch-thick gypsum board be installed over 5/8-inch gypsum board, just to accommodate a reveal detail. If the 1-inch board was required anyway to attain a fire-rating, they have lost that rating at the reveal.Second, I'm not sure that you can get an aluminum reveal that size. It might have to be custom made.
Is the intent to have aluminum exposed at the back of the channel?If the channel is horizontal and the drywall installed on vertical studs, one or the other will have to be notched or discontinuous.Are there other instructions regarding the ends of the channel and how the wallpaper is finished?Are there instructions as to how the channel is to be mounted? (Perhaps the wallpaper holds it in place.)
If the wall is not rated, then a 1" x 1" reveal can be installed easily by using 2 layers of rock. Hang the rock, pop a line, then cut with a router. Dusty. The extruded reveal will straighten out the weakness-waves in the rock, which won't be much with two layers. It will need to be floated out. The wall covering is cut at the outside corner. An extruded reveal insert (outside dimension is 1" x 1") has a small lip and keeps the wall covering from curling. It is a bad idea to cut the wall covering at the inside corner because the covering will curl. The reveal manufacturers also make reveal termination "plugs" that are installed at the same time as the reveal. (The extruded reveal fits into a U-shaped piece that has an inside dimension the same size as the outside dimension of the reveal). If the wall is 1 hour rated, then the same installation but with a 5/8" deep reveal.
Good comments, one and all! If you want to spend the money, you can do just about anything, but understanding both how things go together and what's available often makes it possible to achieve the desired effect easily and without great expense. Suggestions about the wall covering were also valuable. Wrapping the wall covering around the corner into a tight space, trying to make it stick, and still have the base of the reveal clean & shiny is more difficult than it might seem. Working in any small space is always something to consider.