I'm sure there are other more qualified people to answer your question, but I'll give a few pointers. They may not be the specific numbers you're looking for however.
Roses need good air circulation because they tend to get fungal disease alike black spot and powdery mildew. So you'll want to leave sufficient room.
The 4~5 feet probably indicates height.
The SW wall -- is this an end wall of the house or a side wall with an overhead eave and gutter? An end wall will get rain to the base of the wall but a side wall will usually remain somewhat drier. This may influence your decision on how close to plant.
You'll want to leave sufficient room so the thorny canes won't be rubbing up against the wall. You can control this in part by pruning. The rose will also self adjust, in part, because it will tend to grow TOWARDS the light (outward) unless you house is white.
Especially since this is a Grandiflora, meant to be showcased, and not a landscape hedge-type rose, If you have more than one, you'll want to leave sufficient room in between for air circulation (i.e. branches shouldn't overlap/rub against each other). Usually tree and shrub drip line (tip of branch) circle radius is calculated by taking the height and dividing by half -- Or, not to over-complicate things, the height=spacing.
For the fungal issues, I highly recommend spraying your shrubs with 10% milk solution (I call it that but it's actually 1 part milk mixed in 8~10 part water. The bacteria that like milk is highly effective in preventing and outcompeting Powdery Mildew and Black Spot fungi. It also supplies a calcium boost. If you search the forum, you'll see numerous mention of it and may locate some links to scientific articles that has been mentioned as well. I use it to spray my fruit trees, vegetables, strawberries, and my solitary rose bush.
The time to start spraying is when the summer humid season starts, BEFORE any sign of disease appears. Once a week should suffice.
There is a famous story of a head gardener at one of New York's botanical gardens who buried the skin from daily snack banana under favorite rose shrubs. Banana skin provides potassium and other useful nutrients.