Anyone an idea if i can use the garage age as property age?

The reason is to thwart illegal conversions.

And example would be appliances, if you’re replacing appliances you want to use a nice package maybe even stainless if the market can return that investment however you do not need to go to top of the line KitchenAid or Viking, Vulcan subzero etc.In terms of systems if you’re talking single family every property is different and what you do will depend on the age, style, condition and location of property etc.  

They are often jaded by bad experiences and age.

This item should have been included in the initial budget due to its age, but we felt it was functioning well (no pun intended) so it wasn't included.

I didn't come from money and was tought the value of hard work and I WANT to do most of the work myself, although I don't expect to have to do much, so I commend you for instilling that in your son at an early age!

Following up on what Dennis said, depending on the area you're in and the age of the house/mechanicals/roof, your maintenance/capex might be higher.

I admire you starting at such a young age too.

I know I shouldn't let emotion get in the way of business (which is why he did this without telling me first) but they are both single working class middle age women and to make things more complicated, we also live in the building and one of the tenants watches our cat and takes in our mail when we go away. 

Remember the age old saying in real estate investing is that you "make money when you buy."