Don’t tear down those walls
I want to, and intend to, convert our garage into something else. I was originally thinking a granny flat (or, in the wonderfully klunky portland-speak, an Auxiliary Dwelling Unit™,) but have since waffled towards converting it into a little shop/office (shop on the ground floor, office on the top floor.) Either of these conversions require either (a) hiring an architect to do the plans (not so much for the plans, because I've got a large stack of strength of materials notes & constructions books, but for navigating the zoning maze) or (b) digging through the city zoning code by myself.
Digging through the city zoning code is cheaper than hiring someone else to do it, and it's more in keeping with my plan to build a house before I die. The city code is, um, fairly daunting in the various requirements for building structures in the R2.5ad zoning area I live in, and it doesn't take much reading to realize that the existing structure doesn't even come close to meeting current zoning (the current zoning requires a 3 foot setback from the side and back of the property for a new garage that does not contain anything that could be used to make it a livable structure. My garage, which was built 99 years ago -- well before zoning was anything more than a twinkle in the eyes of the city fathers -- so doesn't meet these setbacks it's not funny. The only thing that sets it back on the side is the roof overhanging by 2 feet. And on the back of the lot it appears to be set back by about -4 inches [at least that's how much it appears to overhang the commercial building that's immediately to the northwest of our lot.]) Fortunately for me, and unfortunately for the City of Portland's zoning plans (normally I wouldn't mind having to set the silly building back from the edges of the lot, but we've got a cinder block building immediately to the northeast which comes right up to the edge of the lot, and immediately to the west of our lot is a 6 foot drystone concrete wall, 3 feet of walkway, and another 12 foot tall sheer unwindowed wooden commercial building. We wouldn't exactly spoil the ambiance of the neighborhood if I extended the damned garage up to the property line and put a concrete wall up against the drystone wall to keep debris from falling in between the wall and the garage,) legal buildings that predate zoning don't have to be made compliant with many of the zoning laws when they are modified.
It's not an open invitation to hang out my "I'm a libertarian! Fuck you all!" freak flag and put up a vertical lard rendering plant; there are some zoning requirements that are still there to keep ones neighbors from accidentally lighting your house on fire and running you over with their cars, so I'm stuck with not being able to raise any wall (modulo gable facade) past 10 feet (the existing garage is about 9 feet from sill to the bottom of the gable; 10+ feet if you go down to the exiting concrete floor) and the city /really really/ wants you to echo the architecture of the main building when you modify the outbuilding, but as long as I convert the garage into a greenhouse, artist studio, guest house, accessory dwelling unit, storage building, wood shed, covered deck, covered porch, or covered recreational structure I'm officially within code.
As long as I don't tear it down. Sure, the code claims that I can reconstruct a garage within the footprint of the old structure even if it doesn't conform to code, but the language isn't really emphatic enough to encourage me. And I don't have an architect's license I can wave around and sputter indignantly about when the planning commission claims that I have to cut the eaves off and remove the roof before they'll let me rebuild. And even if they did, the walls are more than 10 feet up to the gable.
So my original plan of converting the structure into a full two-story structure may not work. If I leave the gable dimensions the same as they are right now, I've got 16~17 feet from slab to roof peak, or, if I put a 7'6" ceiling on the ground floor (that's a little higher than my basement ceiling, and I'd be perfectly happy to work down there if I could get all of my supplies off the floor and away from the periodic floods), enough room for an 11' wide room up above.
There's still the teeny detail of the brutally savaged front, the rotted out back, the rotten SW corner (when we regraded that corner of the yard [by taking out 25 wheelbarrow loads of topsoil and dumping it into where the driveway used to be before I converted it to concrete rubble] Russell amused himself by wedging his shovel into the wall until I noticed and mentioned that the best would be unhappy if the garage collapsed and squashed us flat. There's really nothing left in that corner, and I'm afraid the back of the building is being kept up purely by the structural strength of the plywood that was attached when it rotted out the first time,) and the cracked foundation, all of which will have to be redone from scratch before I'm happy with the structural integrity of the building.
But I will have to do this before the building collapses and I have to convince the City of Portland that I'm just rebuilding it on the old foundation.