If you have an exterior water heater/mechanical room that might a good spot.

The mechanics of calculating CO non-resident tax are convoluted and involve your entire income, not just your CO income.

Math, Mechanics, English, Computer Programing, fingerpainting, mowing lawns, selling pizza?

I wouldn't want anything with batteries for the owner's closet, so mechanical lockbox with the OC key.

Shiri:I'm going to preface this with "I'm not an attorney" - however, I do have a Master's degree in Law with an emphasis in real property, trusts, and estates.

for example when I owned my mobile mechanics business I would regularly "overquote" on my estimated time for repair on a customers piece of equipment.

The bathroom renovation is the icing but the mechanicals are the cake.

Are necessary mechanicals for the house still going to be accessible if you finish the basement?

As far as the mechanical work goes thats all on him. he will be piping everything to code (hopefully). if he asks you what type of material you would like to use on this project copper is best for water lines as for one copper joints are stronger than plastic and two copper is natural so your not drinking something that was sitting in plastic for god knows how long. now a days the go to is pex which is fine and also cheaper.

A garage is not considered habitable space and does not meet requirements for sleeping quarters, so you will need to bring it up to code in terms of insulation, electrical, egress, fire, mechanical,  etc.