My initial thoughts about this are that sculptural form as architecture would be a sculpture that happens to incorporate an element of a building, whereas architectural form as sculpture would be primarily concerned about the building, with the sculptural form coming second?
The examples of this kind of sculpture given in the course notes are the architect Frank Gerhy’s ‘Guggenheim Museum of Art’ 1997, in Bilbao, Spain and the sculptor Rachel Whiteread’s ‘Holocaust Memorial’ 2000, sited in Vienna’s Jewish Quarter. These two examples would fit with my initial thoughts, but I can see that the distinction could get very blurred.
Looking into this further it looks like some sculptors also find the distinction blurry and a number of them have looked to merge the two. Siah Armajani invented ‘archi-sculpture’ in 1979, abstract sculptures using architectural elements. Similarly Anthony Caro invented ‘sculpitecture’ in the 1980s for his crossover pieces.
In relation to specific works, Per Kirkeby’s ‘Wanas’, 1994 is very clearly in this category, being a roofless pavilion. Won Ju Lim’s ‘Elysian Field North’ 2000 references the architecture of Vancouver using plexiglass and foam core, with projected images of industrial site played over and through it. These are the more obvious architectural sculptures, being either buildings or cityscapes.
More abstract forms like Caro’s ‘Forum’, 1992-94 obviously reference buildings in the shapes used and the form of the combined structure.
My ‘Residency’ sculptures from stage 1 would fall into this category also.
Less obvious forms might include Sophie Ryder’s ‘Sitting’, 2007, a hare formed from galvanised wire, but cut in half down the middle. The gap between the two halves offers the opportunity to walk through the two halves (if it wasn’t fenced off!) and I believe there is a seat incorporated into the sculpture (although I can’t seem to confirm this, certainly there is a hollow which would allow access to a cave like space), bringing in usefulness and the makings of an enclosed room. As an aside, the materials of this sculpture were very interesting, using flattened wire, but the result is not well formed, nor makes any sense being cut in half!
“Evaluating Structural Form: Is it sculpture, architecture or structure?.” Is an interesting paper on the crossover between these three forms, with the linkage between them being the increasing number of constraints as you go from sculptural form, through architectural form, to structural form. Sculptural form having much more freedom than the other forms, with the only critical criteria being that it will stand up under its own weight.
As to when a sculpture starts to reach this blurred division of forms, it seems to me that pretty much the only criteria is size (either real, or implied). Any large sculpture will (intentionally or not) start forming spaces which might provide cover, or routes through it, or masses sufficient to provide rooms, or use industrial/architectural materials.
Wanas.se, (2015). Konstnär. [online] Available at: http://www.wanas.se/svenska/Konst/Konstn%C3%A4rer/Konstn%C3%A4r.aspx?fid=29 [Accessed 3 Dec. 2015].
Backhouse, J. (2015). Vancouver Art Gallery launches a new series on emerging artists of the Pacific Rim. [PDF] Vancouver: Vancouver Art Gallery. Available at: https://www.vanartgallery.bc.ca/media_room/pdf/100902.pdf [Accessed 3 Dec. 2015].
Saliklis, Edmond P. “Evaluating Structural Form: Is it sculpture, architecture or structure?.” Architectural Engineering (2007): 25.
Collins, J. (2007). Sculpture today. London: Phaidon Press.