This is an excellent, well thought out idea, go for it. It`s certainly not new, but with some sharp marketing and an added twist or two, you should do well in most modest to well-to-do areas.
I would add one convenience that others likely do not...
Have on-site storage trailers or cubes for the clients small-stuff secure storage whilst you`re redoing their `everyman`s castle.`
If you lived in my neighborhood, you`d have my business - if you stored my rather expensive jewelers tools & precious metals stock securely while you worked over my 2400SF 4-car mini-domain and jewelry factory-workshop.
Time to start drafting those business and marketing plans!
Nick
I would add one convenience that others likely do not...
Have on-site storage trailers or cubes for the clients small-stuff secure storage whilst you`re redoing their `everyman`s castle.`
If you lived in my neighborhood, you`d have my business - if you stored my rather expensive jewelers tools & precious metals stock securely while you worked over my 2400SF 4-car mini-domain and jewelry factory-workshop.
Time to start drafting those business and marketing plans!
Nick
I checked with my insurance agent... she informs me that as long as it is located on or adjacent-to my property, and under a secure lock and key (as secure as it now is, or better), it`s covered the same as if it were stored in my workshop/garage under my personal, home & business property policies. (It`s the same as personal property temporarily stored in your locked vehicle... the homeowners policy generally covers that too.)
To ease your mind, you could require a signed liability waiver from your clients... but also inform them they`ll need to check with their insurance agent for coverage as well. You could offer insurance as an option... see your own agent about getting a blanket liability policy to do that. 
Nick
Have you considered approaching local homebuilders to offer your services as an "option" to the new home or an added service?
I have numerous friends who built new homes and then went out and bought a bunch of stuff to try and organize the new garage. It ended up being a very unorganized process and very haphazard.
If a new homeowner could roll this service/products into their mortgage, it may be an attractive package that they would be willing to spend more $$$.
Also, it would be so nice to move into a new home with the garage organization already in place.
Just a thought,
Julie