Hired a electrician (top of google page) who said the whole building was out of code and needed to be rewired at $18k/unit. 

I had to give them the bad news, there were no beach properties that cheap and the real prices are $1M to $5M.These articles pull the sales data for zip codes which can span over 100 sq miles, but then show the income data from a small area (1 to 10 sq miles) within the zip code. 

Additionally, you might want to install a fence with a self-locking gate and make sure all pool equipment is up to code.

Ensure all additions meet local building codes and have proper permits.In your specific case, converting the loft into a bedroom and adding a bathroom could be a smart move, potentially increasing your home's value and appeal to larger families.

@Maciej G.Maybe someone with a local jurisdiction could chime in but at far as international building code goes- there is a heat minimum for a home - but like I said some local areas could have their own laws regarding this.

Once you've identified markets you want to look into, head over to the on-market deal finder and start putting in zip codes you've identified and specify your personal requirements for investing.

Will this new wall be required to have electrical service added per code?  

My current mortgage rate is 4% and the heloc has a promo rate of 1.75% for two years.

These are professionals with additional training and a stricter code of ethics.

Check your state's Landlord Tenant code for direction on how much notice you need to give to go inside.