In theory, one could argue that the average historial capex (both maintenance and expansionary) per year for a time period of 5-20 years should give an estimate of the capex level going forward.

Congratulations im at the same level too here in Boston and looking for GP or syndication to participate , multifamily always the easier and better option for me 

I have also seen total asset value used which is also a pretty horrible metric as it ignores leverage.Why unit count is flawed:A luxury rental in an A-class market is likely worth 10+ entry-level units in a D-market.It ignores partnerships and syndication.

Ensure that you're comparing apples to apples as well, meaning the properties you use for comparison's sake should not only be of a similar style, size, number of bedrooms and bathrooms but should also be in similar quality to the level you intend to remodel your rental.If you are working with an agent and are trying to buy on market, they should be able to help with this.

We started with purchasing turn key suited homes, but due to market shifts and our comfort level we moved to building the same style homes as purpose built rentals….

@Carson Leonard next level thinking.

@Joe Norman so I'm guessing it would be fair to say that, aside from not knowing actual rehab costs or ARV at the outset, it's really up to me going in to decide my own comfort level with leaving money in a project like this.

ya I always wonder what the big attraction for those that live in income tax ( state) see in Texas where there is no income tax at the state level.. and pay those kind of property tax's then pay state income tax on top of it.. 

I've had surface level intro into Real Estate, both through research and through real life experience.

I have never added insulation on my personal residences or flips, beyond my gut level renovations.