@Adam Pervez estimating semi fixed expenses is easy, you can easily pull tax amounts, get estimates for insurance, you should know what your monthly principle and interest should be etc...Most newer investors get into trouble estimating the variable costs of CapEx and maintenance. 

If you go down this road I would aim for finishes that are most forgiving - polyurethane without stain, and matter or satin are more forgiving than semi-gloss or high-gloss.

Do they tear down old homes in mature neighbourhoods  and intensify by building towns or semi-detached dwellings?

Recently a builder friend of mine decided to semi-retire and coach me into the building business.

I am semi active in acquisition side of wholesale aside from having a traditional real estate team.

I have a showroom in a commercial area and have long planned on making a small Design Studio in about 10 years as a 'semi retirement gig' in my back yard at home.

I am just wrapping up 30 years in law enforcement and while its only semi-related, I completely get how the sacrifices often go unnoticed - I truly believe they are appreciated by most but being safe here in the USA is just expected so it becomes the norm. 

The other option is the easiest path of resistance and which most use and just get a semi good idea from them and go from there.

Put systems and processes in place to do so.One such tidbit:  I do semi-annual walkthrough inspections. 

If your within 20 miles or a larger metro area, offer Semi and Trailer parking.