I believe I have a knack for this (I am in the construction field, with a BS in mechanical engineering..numbers and building things are in my blood).

I can estimate mechanical, plumbing, and fire, but not roof or carpentry.  

I currently work as a mechanical engineer designing HVAC systems for commercial projects, however, that is not how I would like to describe myself. 

I would assume this means mechanical components such as furnaces and hot water tanks would be included?

I have spend 30 years in the construction field (mostly on the mechanical side HVAC) but have a pretty good sense of building structures.

But that was 3 years ago.Since I have owned this property I have had it rented for a decent amount, cash flowing monthly and no repairs needed (this wasn't by chance I knew all of the mechanical items had been in great shape) .

I am a formal mechanical engineer, turned real estate investor (i know!).

Ali I'm a mechanical engineer in HVAC industry at the moment.Thanks to everyone for the posts.

I am trying to figure out costs for my first house.I'm a Mechanical Engineer, but I specialize in design, so the bones of the house are very important to me.  

Double the maintenance, double the tenants, double the mechanicals ... ;).