That said I just did a reno (same building, no architect), ended up replacing all the plumbing in unit to bring it to code - not be something an architect would be able to predict.

Does this also include the building structure and building systems like electrical, plumbing, and HVAC? 

On one of the houses, he pulled a building permit for plumbing, and that permit has expired before the bathrooms were finished so inspector did not do the inspection.I have another guy that can finish out the job, but he is not a GC and cannot pull permits.

They just want people living in safe places, with proper egress, Proper ceiling height, and electric and plumbing installed properly.

Are the systems HVAC, elec. and plumbing up to date?

@Odie AyagaWe think a mostly cosmetic property would be good for our first property, but we're not afraid of some minor electrical, plumbing, mechanical, etc issues.

My only challenge was a 1 month delay in construction because the units in this building (1975 high-rise construction) didn't have individual water shut off valves, so in order to do plumbing work, we had to wait for the building to shut down water to the entire tower.

Also, does anyone have thoughts on using a home inspector vs. hiring inspectors based on specialty (plumbing, roofing, etc.)?

Building a budget: Roof, electrical, exterior siding/paint, gutters, plumbing, heat, flooring, kitchen, bathroom, paint. 

Hey Kayla,As @Ned Carey stated, by adding all of these additional rooms and running plumbing & electrical himself, you are putting yourself at a huge risk.