Ancient armies had 3 kind of warriors: The first was calvary (armed men on horseback or chariots) .

I'm starting to understand why so many rentals have ancient fixtures with 20 layers of paint!

Unfortunately, we're way under budget to afford anything there unless it's an ancient one bathroom! 

Looks like the OP is ancient, I was about to say the same thing when I realized it.

However if you have one like that and it is off base from you normal range I imagine you could use that methodology.

The flipping book talks specifically about the order in which you do things working up to an offer (including when to bring in a contractor for estimates), and the rehab estimating book will give you a methodology for estimating rehab costs.

@Neil Da SilvaI would say 'history...' because the PTB (Powers That Be) tend to run the same plays, from the empirical playbooks moderne, and ancient, time and again.

General Question:Several of my rentals have boilers across the spectrum of quality and age.  My oldest boiler is in a 5 BR 2 BA house.  It's been producing a LOT of carbon monoxide, so much that I feel like it's a haz...

The valuator should determine which methodologies are to be utilized in developing the opinion of value of the subject property.

He may be right, it's an ancient 4" cast iron drain that most plumbers hate to mess with.