Deck layout advice for working around AC unit
I'm about to attempt to build a deck in our backyard. There are a few things I'm trying to figure out. First, let me begin by explaining my situation.
Attached is a rough sketch of the back of the house. It's a semi, with the neighbour side not shown in the sketch. The elevated door is the kitchen door and I'm planning to make the deck at that level. The alley is concrete, with two concrete stairs leading to garden level where I currently have flagstones that I'm planning to relocate when building the deck. The gray box you see on the flagstones is the AC unit.
I'm planning to have the deck span the entire width (14') of the house and make it extend around 10' away from the house. I'm definitely not going to build my deck over the AC unit, so I'll probably end up making a notch to go around the AC unit. However, my concern is that I may not have enough working space around the AC unit to use an auger to dig holes for footings. I may need to do some tedious manual digging (lot's of roots in the soil!).
I don't know if I can get away with precast concrete piers. The deck is not that high (2' from garden level and 2 2/3' from alley) and the soil is fairly compacted, but I guess I need to check the local building code for that (East York, Toronto, Ontario).
I'm also wondering if I could use the concrete wall surrounding the alley as footing. It's solid concrete that probably won't move anywhere with the weight of the deck. But, I don't know if the code would allow that...
Any advice based on my situation will be appreciated.